| Relativistic astrophysics and Gravitation |
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Conference files - program, list of participants, photos ...
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Contacts: asmik96@astrin.uz |
Astronomiya Instituti is inviting you to a scheduled Zoom meeting.
Topic: May 12-14, 2021, International Online Workshop on Relativistic Astrophysics and Gravitation, IWRAG-2021
Time: This is a recurring meeting Meet anytime
Join Zoom Meeting
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Meeting ID: 915 3306 8962
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We are holding international online workshop on Relativistic Astrophysics
and Gravitation, IWRAG-2021 in Ulugh Beg Astronomical Institute, Uzbekistan
during 12 - 14 May 2021. The purpose of the meeting is to bring up the regional
(Central Asian) astrophysicists specialized in general relativity & relativistic
astrophysics and the international scientific community together and give an
opportunity to exchange the scientific results in order to expand contacts and the
scientific collaborations with the international institutions.
It is necessary to underline that during the last twenty five - thirty years due
to the attention and assistance of the local, regional and international scientific
community there was a great success in the development and establishment of new
well functioning and competitive scientific groups specialized in general relativity
& relativistic astrophysics in Uzbekistan, Kazakhstan, Kyrgyzstan. Therefore, one
of the aims of the workshop is to celebrate the great achievements made in the
Central Asia, and hold an international workshop on Relativistic Astrophysics of
Compact Gravitational Objects with the involvement of European & South/East
Asian collaborators and Central and South/East Asian scientists.
The total number of participants expected to participate in the activity will
be over 80-90 with substantial involvement of scientists from Uzbekistan,
Kazakhstan, Kyrgyzstan, Pakistan, China and India. There is good number of
participants from USA, Holland, Germany, Italy, Japan, Czech Republic etc. We
are excited about the prospects of organizing such an event and of collecting under
the same scientific scope scientists from many different countries in Central and
South/East Asia.
It is expected that IWRAG-2021 would have a great opportunity for
scientists and students specialized in relativistic astrophysics and general
relativity. Another goal of the activity is to celebrate the recent triumphal
discoveries as detection of gravitational waves by LIGO-VIRGO, first image of
M87 by EHT (Event Horizon Telescope), multimessenger era in astronomy
starting 170817 and also to show the dynamism of the scientific activities in this
area in the Central Asia.
The scientific program of the workshop IWRAG-2021 is available at:
http://astrin.uz/uz/news/conference/2021-05-12/downloads
Given that the scope of the workshop is quite wide-spread and we expect its
wide ranging impact on Mathematical Physics, General Relativity and Relativistic
Astrophysics, we expect that refereed plenary and 40 minutes talks would be
published in the special issue of the Arabia Journal of Mathematics by Springer
indexed in Web of Sciences and Scopus:
https://www.springer.com/journal/40065
It is expected that papers for 20 minutes contributed talks will be published
in the special issue of Uzbek Journal of Physics:
http://www.ufj.uz/index.php/ufj/index
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| Program |
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| May 12, Wednesday |
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May 12
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(UTC+5)
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Conference Opening 10:30
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Day 1
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10:30 Opening Ceremony
At the opening ceremony the participants of IWRAG-2021 will be greated by
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Ajit Kembhavi
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The former Director of the IUCAA/Vice President of the International Astronomical Union
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Shuhrat Ehgamberdiev
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The Director of Ulugh Beg Astronomical Institute
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11:00
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Plenary Talks
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Speaker/Chair
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Title of talk
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Chair : Ahmadjon Abdujabbarov
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11:00 - 11:20
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Bobomurat Ahmedov
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Development and Perspectives of Relativistic Astrophysics in Uzbekistan
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11:20 - 11:40
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Medeu Abishev
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Effects of nonlinear electrodynamics of vacuum in the magnetic field of a magnetar
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11:40 - 12:20
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Naresh Dadhich
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Higher dimensional rotating black holes cannot be formed by an accretion process
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12:20 - 13:00
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Cosimo Bambi
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Testing General Relativity with black hole X-ray data: recent progress and future developments
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13:00
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13:00 - 14:00
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Lunch/Coffee break
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Chair : Shuhrat Mardonov
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14:00
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14:00 - 14:40
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Jutta Kunz
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Scalarized Black Holes
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14:40 - 15:20
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Wenbiao Han
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Testing propagation effects of gravitational waves
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15:20 - 16:00
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Farrukh Fattoyev
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GW190814: Impact of a 2.6 solar mass neutron star on the nucleonic equations of state
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16:00
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16:00 - 17:00
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Lunch break
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17:00
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Contributed Talks
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Speaker/Chair
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Title of talk
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Chair : Ashfaque Bokhari
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17:00 - 17:20
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Ahmdajon Abdujabbarov
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Optical properties of black hole
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17:20 - 17:40
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Muhammad Zaeem Ul Haq Bhatti
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Dynamical Analysis of Self-gravitating Objects in Modified Gravity
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17:40 - 18:00
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Zoha Tariq
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Effects of electromagnetic field on the structure of massive compact objects
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18:00
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18:00 - 18:20
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Rabia Saleem
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Study of Interacting Dark Sectors using Chevallier-Polarsky-Linder Type Parametrization
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18:20 - 18:40
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Zeeshan Yousaf
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The Measure of Complexity in Spherical Relativistic Geometry
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18:40 - 19:00
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Ibrar Hussain
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Broken Lie Symmetries and the Energy Content of Some Charged Black Hole Spacetimes
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19:00
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| May 13, Thursday |
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May 13
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(UTC+5)
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Day 2
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11:00
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Plenary Talks
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Speaker/Chair
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Title of talk
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Chair : Yusufjon Tillayev
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10:00 - 10:40
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Sarah Antier
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Multi-messenger observations with GRANDMA
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11:00 - 11:40
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Ernazar Abdikamalov
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Explosions of massive stars
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11:40 - 12:20
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Sandybek Kunakov
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To the chromodynamics of nuclei fissioning
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12:20 - 13:00
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Pankaj Joshi
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Gravitational Collapse, Black Holes and Naked Singularities
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13:00
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13:00 - 14:00
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Lunch/Coffee break
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Chair : Askar Abdikamalov
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14:00
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14:00 - 14:40
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Toshitaka Kajino
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Nucleosynthetic Evidence for Primordial & Stellar Black Holes and Binaries
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14:40 - 15:20
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Mubasher Jamil
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Gravitational lensing and shadows for some spherically symmetric black holes
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15:20 - 16:00
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Yuri Shtanov
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Constraints in inflationary magnetogenesis
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16:00
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16:00 - 17:00
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Lunch break
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17:00
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Contributed Talks
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Speaker/Chair
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Title of talk
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Chair : Ugur Camci
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17:00 - 17:20
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Martin Kolos
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Charged particle motion in black hole magnetosphere
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17:20 - 17:30
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Viktoriya Giryanskaya
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The gravitational wave signal from core-collapse supernovae
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17:30 - 17:40
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Javlon Rayimbaev
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Distinguishing regular and singular black holes in modified gravity
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17:40 - 17:55
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Dmitriy Ovchinnikov
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Light curves of the hot spots on the circular orbits around Generic Regular Black Hole Related to Nonlinear Electrodynamics with Maxwellian Weak-field Limit
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18:00
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17:55 - 18:10
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Aleksandra Demyanova
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Dynamics of charged and magnetized particles around cylindrical black holes immersed in external magnetic field
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18:10 - 18:25
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Dina Kairatkyzy
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Dark matter halo
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18:25 - 18:40
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Bakhtiyor Narzilloev
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Kerr-Taub-NUT spacetime to explain the energetics of black hole candidates
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18:40 - 18:50
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Pulat Tadjimuratov
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Effects of STVG modifiel gravity on neutrons star radiation
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18:50 - 19:00
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Yunus Turaev
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Kerr-Newman black holes as sources of relativistic jets
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19:00
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| May 14, Friday |
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May 14
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(UTC+5)
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Day 3
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11:00
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Plenary Talks
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Speaker/Chair
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Title of talk
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Chair : Kuantay Boshkayev
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11:00 - 11:40
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Luca Baiotti
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Gravitational waves from binary neutron stars
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11:40 - 12:20
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Asghar Qadir
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Virial clouds and frequency asymmetry in galactic halos
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12:20 - 12:40
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Dana Alina
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Magnetic field in Monoceros OB1 East cloud
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12:40 - 13:00
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Bekdaulet Shukirgaliyev
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The evolution star clusters with centrally peaked star-formation efficiency
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13:00
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13:00 - 14:00
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Lunch/Coffee break
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Chair : Francesco De Paolis
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14:00
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14:00 - 14:40
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Vladimir Dzhunushaliev
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Nonperturbative quantization a la Heisenberg
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14:40 - 15:20
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Sushant Ghosh
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Shadows of hairy Kerr black holes and constraints from M87*
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15:20 - 16:00
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Daniele Malafarina
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Properties of a class of black hole mimickers
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16:00
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16:00 - 17:00
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Lunch break
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17:00
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Contributed Talks
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Speaker/Chair
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Title of talk
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Chair : Bobomurat Ahmedov
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17:00 - 17:20
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Rustam Ibadov
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The fundamental equation of the field theory in De Sitter pulse space
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17:20 - 17:35
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Yusufjon Tillayev
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Perspectives of optical astronomy at Maidanak observatory
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17:35 - 17:45
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Sardor Murodov
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Wormholе solutions in highеr curvаturе thеoriеs
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18:00
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17:45 - 18:00
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Sardor Tojiev
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Gauss-Bonnet boson stars
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18:00 - 18:20
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Algis Malybayev
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On exact dyon-like black hole solutions in the model with two Abelian gauge fields and two scalar fields
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18:20 - 18:40
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Kuantay Boshkayev
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Quasinormal modes in the field of a dyon-like dilatonic black hole
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18:40 - 18:50
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Shukhrat Mardonov
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Coupled dynamics of two polarons-one-dimensional Bose - Einstein condensate in a parabolic potential
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18:50 - 19:00
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Nozima Juraeva
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Test particles around Hayward black holes surrounded by quintessential medium
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19:00
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| SOC/LOC |
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| International Advisory Committee |
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Bobomurat Ahmedov (AI, Uzbekistan)
Daniele Malafarina (Nazarbayev University, Kazakhstan)
Ernazar Abdikamalov (Nazarbayev University, Kazakhstan)
Medeu Abishev (Al-Farabi University, Kazakhstan)
Ashfaque Bokhari (King Fahd University of Petroleum & Minerals, Saudi Arabia)
Ugur Camci (Roger Williams University, USA)
Naresh Dadhich (IUCAA, India)
Viktoriya Morozova (PennState, USA)
Luciano Rezzolla (Frankfurt, University, Germany)
Sushant Ghosh (Centre for Theoretical Physics, India)
Jutta Kunz (Oldenburg University, Germany)
Ahmadjon Abdujabbarov (AI, Uzbekistan)
Bobir Tosmatov (AI, Uzbekistan)
Farrukh Fattoyev (Manhattan College, USA)
Cosimo Bambi (Fudan University, China)
Wenbiao Han (ShAO, China)
Zdenek Stuchlik (Opava, Czech Republic)
Martin Kolos (Opava, Czech Republic)
Asghar Qadir (Islamabad, Pakistan)
Francesco de Paolis (Lecce, Italy)
Mariafelicia De Laurentis (Napoli, Italy)
Muhammad Sharif (Punjab University, Pakistan)
Mubasher Jamil (China)
Yuri Shtanov (Bogolyubov Institute for Theoretical Physics, Kiev, Ukraine)
Yuri Vyblyi (B. I. Stepanov Institute of Physics, Minsk, Belarus)
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| Local Organizing Committee |
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Ahmedov Bobomurat, Chairman
Abdujabbarov Ahmadjon
Toshmatov Bobir
Tursunov Arman
Abdikamalov Askar
Tojiev Sardor
Shaymatov Sanjar
Atamurotov Farruh
Mardonov Shuhrat
Rayimbaev Djavlanbek
Boboqambarova Madina
Rahimov Ozodbek
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| List of сonfirmed participants (90) |
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| Javlon Rayimbaev |
Country: Uzbekistan
| Presentation type: Contributed talk
Presentation title: «Distinguishing regular and singular black holes in modified gravity»
Organization: «Ulugh Beg Astronomical Institute»
Abstract ...
This paper is devoted to investigate the possible ways of distinguishing regular and singular black holes (BHs) in modified gravity (MOG) called regular MOG (RMOG) and Schwarzschild MOG (SMOG) BHs through observational data from twin peak QPOs which are generated by test particles in stable orbits around the BHs. The presence of MOG field causes to sufficiently the mpeak in effective potential for radial motion of test particles. The effect of MOG parameter on specific angular momentum and energy has also studied. As a main part of the paper, we focus on investigations of QPOs around SMOG and RMOG BHs in RP model and the relations of upper and lower frequencies of twin peak QPOs in SMOG and RMOG BH models together with extreme rotating Kerr and Schwarzschild BH. Moreover, possible parameters for the central BHs of the objects GRS J1915+105 and XTE 1550-564 have also obtained numerically. Finally, we provide comparisons of innermost stable circular orbit (ISCO) and the orbits where twin peak QPOs with the ratio 3:2 taken place and show that QPOs can not be generated at/inside ISCO and there is correlation between radius of ISCO and QPO orbits.
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| Aigerim Shapiyeva |
Country: Kazakhstan
| Presentation type: Without report
Organization: «IITU»
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| Ergali Kurmanov |
Country: Kazakhstan
| Presentation type: Without report
Organization: «Al-Farabi Kazakh National University»
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| Talgar Konysbayev |
Country: Kazakhstan
| Presentation type: Without report
Organization: «Al-Farabi Kazakh National University»
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| Ashok Joshi Joshi |
Country: India
| Presentation type: Without report
Organization: «International center for cosmology(ICC), India»
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| Sanjar Shaymatov |
Country: Uzbekistan
| Presentation type: Contributed talk
Organization: «Ulugh Beg Astronomical Institute»
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| Shukhrat Mardonov |
Country: Узбекистан
| Presentation type: Contributed talk
Presentation title: «Coupled dynamics of two polarons and a one-dimensional Bose - Einstein condensate in a parabolic potential»
Organization: «Ulugh Bek Astronomical Institute»
May14|
Presentation file not loaded|Download video
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| Jay Verma |
Country: India
| Presentation type: Without report
Organization: «International centre for Cosmology»
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| Dipanjan Dey |
Country: India
| Presentation type: Without report
Organization: «International center for cosmology»
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| Aleksander Serebryanskiy |
Country: Kazakhstan
| Presentation type: Without report
Organization: «Fesenkov Astrophysical Institute»
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| Parth Bambhaniya |
Country: India
| Presentation type: Without report
Organization: «ICC, Charusat University»
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| Sarah Antier |
Country: Netherlands
| Presentation type: Plenary talk
Presentation title: «Multi-messenger observations with GRANDMA»
Organization: «University of Amsterdam»
May13|
Presentation file loaded|Download video
Abstract ...
The multi-messenger astronomy aims at study astrophysiacal events through differents messenger : GW, photons, neutrinos.
The 170817 joint detection of GW and photons (at all wavelengths) has proven the relevance of multi-messengers studies. Yet it also showed the necessity of coordination and preparation of electromagnetic observations (from gamma to radio) to have relevant constraints on physical parameters.
In this talk, I will present the Global Rapid Advanced Network Devoted to the Multi-messenger Addicts (GRANDMA), a network of telescopes aiming to detect, identify and characterize electro-magnetic counterparts to gravitational-wave sources.
I will detail the consortium, its capabilities, scientific programm and public tools develloped for the time domain astronomy. I will conclude by presenting a summary of our scientific results after O3 LIGO/Virgo run and the prospect we will be conducting to prepare the next GW observation runs.
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| Aqsa Yasmin |
Country: Pakistan
| Presentation type: Without report
Organization: «National University of Sciences and Technology»
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| Davronbek Mirzaqulov |
Country: Uzbekistan
| Presentation type: Without report
Organization: «Ulugh Beg Astronomical Institute»
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| Farruh Atamurotov |
Country: Uzbekistan
| Presentation type: Without report
Presentation title: «Shadow of charged rotating black hole in the presence of perfect fluid dark matter»
Organization: «Inha university in Tashkent»
Abstract ...
We analysed the shadow cast by charged rotating black hole (BH) in presence of perfect fluid dark matter (PFDM). We studied the null geodesic equations and obtained the shadow of the charged rotating BH to see the effects of PFDM parameter $\gamma$, charge $Q$ and rotation parameter $a$, and it is noticed that the size as well as the shape of BH shadow is affected due to PFDM parameter, charge and rotation parameter. Thus, it is seen that the presence of dark matter around a BH affects its spacetime. We also investigated the influence of all the parameters (PFDM parameter $\gamma$, BHs charge $Q$ and rotational parameter $a$) on effective potential, energy emission by graphical representation, and compare all the results with the non rotating case in usual general relativity.
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| Nuriddin Kurbonov |
Country: Узбекистан
| Presentation type: Without report
Organization: «Ulugbek Astronomical Institute»
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| Shafqat Ul Islam |
Country: India
| Presentation type: Without report
Organization: «Jamia Millia Islamia»
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| Askar Abdikamalov |
Country: Uzbekistan
| Presentation type: Without report
Organization: «Fudan University, Ulugh Beg Astronomical Institute»
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| Yusufjon Tillayev |
Country: Uzbekistan
| Presentation type: Contributed talk
Presentation title: «Perspectives of optical astronomy at Maidanak observatory»
Organization: «Ulugh Beg Astronomical Institute (UBAI)»
May14|
Presentation file not loaded|Download video
Abstract ...
The capabilities of the Maidanak observatory (66°56”E, 38°41”N) for optical astronomy are presented. Optical properties of the atmosphere above the observatory are reviewed. Site testing results of new 4 m telescope project are presented. A few places inside the observatory and nearby summits are considered as candidate sites. The most optimal place in terms of the ground layer turbulence must be chosen. The ESO LuSci lunar scintillometer will be used for comparison of the ground layer turbulence at candidate places.
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| Dana Alina |
Country: Kazakhstan
| Presentation type: Contributed talk
Presentation title: «Magnetic field in Monoceros OB1 East cloud»
Organization: «Nazarbayev University»
May14|
Presentation file not loaded
Abstract ...
Magnetic fields are one of the key factors that regulate star formation process from the largest scales of molecular clouds down to prestellar cores.
I will present the analysis of the large scale magnetic field properties of the Monoceros OB1 Eastt molecular cloud. This work joins observational and theoretical approaches and combines different types of data. We show that the magnetic field in the Monoceros OB1 East cloud is dynamically important, but its exact role is different in the two distinct parts of the cloud.
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| Temurbek Mirzaev |
Country: Uzbekistan
| Presentation type: Without report
Organization: «National University of Uzbekistan»
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| Pulat Tadjimuratov |
Country: Узбекистан
| Presentation type: Contributed talk
Presentation title: «Effects of STVG modifiel gravity on neutrons star radiation»
Organization: «Ulugh Beg Astronomical Institute»
May13|
Presentation file loaded|Download video
Abstract ...
We performed magnetospheric studies in STVG (MOG) model to analyze how it effects the radiation of neutron stars and deathline of radiopulsars. Obtainel results may hint to an explanation of part-time pulsar phenomenon.
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| Bobur Turimov |
Country: Uzbekistan
| Presentation type: Without report
Organization: «UBAI»
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| Javlon Rayimbaev |
Country: Узбекистан
| Presentation type: Without report
Organization: «Ulugh Beg Astronomical Institute»
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| Vladimir Dzhunushaliev |
Country: Казахстан
| Presentation type: Plenary talk
Presentation title: «Nonperturbative quantization a la Heisenberg»
Organization: «al-Farabi KazNU»
May14|
Presentation file loaded|Download video
Abstract ...
Nonperturbative quantization method in field theories, including gravity, is considered. The closure problem for an infinite system of Green's equations describing a strongly quantum-field interacting system is discussed. It is shown that modified gravitational theories can be considered as approximate phenomenological models in quantum gravity. Various special cases are discussed: F (R) gravity, Weyl gravity, nonperturbative QED on the Hopf bundle, and so on.
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| Misbah Shahzadi |
Country: Pakistan
| Presentation type: Without report
Organization: «COMSATS University Islamabad, Lahore campus»
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| KAMRAN ABBASI |
Country: Pakistan
| Presentation type: Without report
Organization: «NUST ISLAMABAD»
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| Abdullo Hakimov |
Country: Uzbekistan
| Presentation type: Without report
Organization: «Astronomical Institute, Uzbekistan»
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| Kuantay Boshkayev |
Country: Казахстан
| Presentation type: Contributed talk
Presentation title: «Quasinormal modes in the field of a dyon-like dilatonic black hole»
Organization: «Kazakh National University»
May14|
Presentation file not loaded|Download video
Abstract ...
Quasinormal modes of massless test scalar field in the background of gravitational field for a non-extremal dilatonic dyonic black hole are explored. The dyon-like black hole solution is considered in the gravitational $4d$ model involving two scalar fields and two 2-forms. It is governed by two 2-dimensional dilatonic coupling vectors $\vec{\lambda}_i$ obeying $\vec{\lambda}_i (\vec{\lambda}_1 + \vec{\lambda}_2) > 0$, $i =1,2$.
Quasinormal modes for a massless scalar (test) field in the eikonal approximation are obtained and analysed. These modes depend upon a dimensionless parameter $a$ ($0 < a \leq 2$) which is a function of $\vec{\lambda}_i$. For limiting strong ($a = +0$) and weak ($a = 2$) coupling cases, they coincide with the well-known results for the Schwarzschild and Reissner-Nordstr\"om solutions. It is shown that the Hod conjecture, connecting the damping rate and the Hawking temperature, is satisfied for $0 < a \leq 1$ and all allowed values of parameters.
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| Medeu Abishev |
Country: Казахстан
| Presentation type: Plenary talk
Presentation title: «Effects of nonlinear electrodynamics of vacuum in the magnetic field of a magnetar»
Organization: «Al Farabi Kazakh National University»
May12|
Presentation file not loaded|Download video
Abstract ...
The nonlinear effect of the magnetar's magnetic field to the propagating gamma ray is calculated. Equations of motion for electromagnetic pulses transmitted in a strong magnetic field of magnetar by two normal modes with mutually orthogonal polarization are constructed. The difference ∆t in propagation times of normal waves from the common source of electromagnetic radiation to the receiver is calculated. It is shown that the forward part and the ”tail” by length c∆t of any hard radiation pulse due to the nonlinear electromagnetic influence of the magnetic dipole and quadrupole fields turn out to be linearly polarized in mutually perpendicular planes, and the remaining part of the pulse must have elliptical polarization.
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| Muhammad Bilal Muhammad Tufail |
Country: Pakistan
| Presentation type: Without report
Presentation title: «Modified Relativistic Dynamics»
Organization: «Abdus Salam School of Mathematical Science»
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| Dmitriy Ovchinnikov |
Country: Czech Republic
| Presentation type: Contributed talk
Presentation title: «Light curves of the hot spots on the circular orbits around Generic Regular Black Hole Related to Nonlinear Electrodynamics with Maxwellian Weak-field Limit»
Organization: «Slezská univerzita v Opavě»
May13|
Presentation file loaded|Download video
Abstract ...
Photon motion in the vicinity of the Generic Regular Black Hole Related to Nonlinear electrodynamics (GRBHNED) described by the null geodetics of corresponding effective geometry. In this talk the semi analytical method for the construction of the light curves from the hot spots on the circular orbits in vicinity of GRBHNED with Maxwellian Weak-field Limit will be presented. Generated light curves will be compared with those generated by hots spots in Schwarzschild and Reissner-Nordström spacetimes.
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| Michele Maiorano |
Country: Italy
| Presentation type: Without report
Organization: «Università del Salento»
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| Antonio Franco |
Country: Italy
| Presentation type: Without report
Organization: «University of Salento»
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| Furqat Sariqulov |
Country: Uzbekistan
| Presentation type: Without report
Organization: «National University of Uzbekistan»
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| Asghar QADIR |
Country: Pakistan
| Presentation type: Plenary talk
Presentation title: «Virial clouds and frequency asymmetry in galactic halos»
Organization: «Abdus Salam School of Mathematical Sciences, Government College University, Lahore»
May14|
Presentation file loaded|Download video
Abstract ...
In 1995 it had been proposed that there would be molecular hydrogen clouds in galactic halos and that they could be seen by an asymmetric frequency shift of the CMB on either side of the galaxy, essentially like a Doppler shift. This was seen in 2011 and confirmed in 2012 for M31, and later in other galaxies of the local cluster. It has been used to study the rotation of galactic halos. To be able to go further, one needs to model the clouds. It has been suggested that these clouds have a viral temperature equal to the CMB temperature. In this talk this work will be reviewed.
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| Ulugbek Kurbanov |
Country: Uzbekistan
| Presentation type: Without report
Organization: «INP»
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| MISBA AFRIN |
Country: INDIA
| Presentation type: Without report
Organization: «JAMIA MILLIA ISLAMIA»
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| Ozodbek Rakhimov |
Country: Uzbekistan
| Presentation type: Without report
Organization: «UBAI»
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| Bobir Toshmatov |
Country: Uzbekistan
| Presentation type: Without report
Organization: «UBAI»
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| Noraiz Tahir |
Country: Italy
| Presentation type: Without report
Organization: «University of Salento Lecce»
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| Pankaj Joshi |
Country: India
| Presentation type: Plenary talk
Presentation title: «Gravitational Collapse, Black Holes and Naked Singularities»
Organization: «International Center for Cosmology, Charusat University»
May13|
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Abstract ...
Einstein's theory of gravity predicts the existence of Space-time Singularities in physically reasonable scenarios, such as gravitational collapse of massive stars in the Universe. These Singularities may be hidden within a Black Hole, or visible to faraway observers in the Universe, also called Naked Singularities. We discuss these theoretical developments, and the current efforts to make a direct observational detection of these entities. Quantum gravity effects dominate near naked singularities, which we may also call 'Quantum Stars', offering an opportunity to test the quantum theories of gravity. The connection to observational missions such as the Event Horizon Telescope, Gravitational Waves, and others are indicated, and recent emerging theoretical developments are pointed out.
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| Muhammad Sharif |
Country: pakistan
| Presentation type: Without report
Organization: «University of the Punjab»
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| Asif Mehmood |
Country: Pakistan
| Presentation type: Without report
Organization: «University of Peshawar»
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| SUSHANT GHOSH |
Country: India
| Presentation type: Plenary talk
Presentation title: «Shadows of hairy Kerr black holes and constraints from M87*»
Organization: «Jamia Millia Islamia»
May14|
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Abstract ...
We take on an extensive study of the rotating hairy Kerr black holes, which encompasses, in particular cases, the Kerr black hole ($\alpha=0$). We investigate ergosphere and shadows of the black holes to infer that their size and shape are affected due to the $l_0$ and are found to harbour a richer chaotic structure. In particular, the hairy Kerr black holes possess smaller size but more distorted shadows when compared with Kerr black holes. We also estimate the parameters $l_0$ and $a$ associated with hairy Kerr black holes using the shadow observables. The inferred circularity deviation $\Delta C \leq 0.1$ for the M87* black hole puts a constraint on hairy Kerr black hole parameter $a$, whereas shadow angular diameter $\theta_{d}=42 \pm 3 \mu as$, within $1 \sigma$ region, for a given choice of $\alpha$, also places bounds on the parameters $a$ and $l_0$. Interestingly, the axis ratio obeying $1< D_x \lesssim 4/3$ is in agreement with the EHT results and thus eventuates in the hairy Kerr black holes being suitable candidates for astrophysical black holes.
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| Ugur Camci |
Country: USA
| Presentation type: Without report
Organization: «Roger Williams University»
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| Rahul Walia |
Country: India
| Presentation type: Without report
Organization: «Jamia Millia Islamia, New Delhi»
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| Yunus Turaev |
Country: Uzbekistan
| Presentation type: Contributed talk
Presentation title: «Kerr-Newman black holes as sources of relativistic jets»
Organization: «Ulugh Beg Astonomical Institute»
May13|
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| Malika Xudoyberdiyeva |
Country: Uzbekistan
| Presentation type: Contributed talk
Presentation title: «Test particles around Hayward black holes surrounded by quintessential medium»
Organization: «National University of Uzbekistan»
Abstract ...
Based on extension of Kiselev's spacetime metric, we have investigated a Hayward black hole surrounded by a quintessence. We have selected the cases when the quintessence state parameter ω =-2/3, ω =-1/2 and ω =-0.6. Using the spacetime metric of the black hole surrounded by the quintessence, we have determined the effective potential for test particles motion. By analyzing the effective potential of test particles (photon), we have investigated the null geodesics and the typss of orbits of the Hayward black hole surrounded by quintessence corresponding to different energy levels.
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| Nozima Juraeva |
Country: Uzbekistan
| Presentation type: Contributed talk
Presentation title: «Test particles around Hayward black holes surrounded by quintessential medium»
Organization: «UBAI»
May14|
Presentation file not loaded
Abstract ...
Based on extension of Kiselev's spacetime metric, we have investigated a Hayward black hole surrounded by a quintessence.
We have selected the cases when the quintessence state parameter ω =-2/3, ω =-1/2 and ω =-0.6. Using the spacetime metric of the black hole surrounded by the quintessence, we have determined the effective potential for test particles motion.
By analyzing the effective potential of test particles (photon), we have investigated the null geodesics and the typss of orbits of the Hayward black hole surrounded by quintessence corresponding to different energy levels.
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| Aigerim Otebay |
Country: Kazakhstan
| Presentation type: Poster
Presentation title: «Survivability of star clusters after instantaneous gas expulsion with Dehnen models»
Organization: «Fesenkov Astrophysical Insitute»
Abstract ...
TBA
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| Bekdaulet Shukirgaliyev |
Country: Kazakhstan
| Presentation type: Contributed talk
Presentation title: «The evolution star clusters with centrally peaked star-formation efficiency»
Organization: «Energetic Cosmos Laboratory, Nazarbayev University»
May14|
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Abstract ...
Star clusters are useful source of information about the dynamics and star-formation history of their host galaxies. Therefore is it very important to understand the formation and evolution of these bright building blocks of galaxies. We study the evolution of star clusters formed according to the local-density-driven clustered star formation theory. The constant star-formation efficiency per free-fall time leads to the centrally peaked star-formation efficiency profile in gas embedded clusters formed from centrally concentrated gas clumps. We discuss how such clusters response to the consequences of gas expulsion and the to impact of the tidal field.
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| Francesco De Paolis |
Country: Italy
| Presentation type: Without report
Organization: «University of Salento»
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| Madina Boboqambarova |
Country: Uzbekistan
| Presentation type: Without report
Organization: «UBAI»
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| Arman Tursunov |
Country: Uzbekistan
| Presentation type: Without report
Organization: «UBAI»
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| Sandybek Kunakov |
Country: Казахстан
| Presentation type: Plenary talk
Presentation title: «To the chromodynamics of nuclei fissioning»
Organization: «Al Farabi National University»
May13|
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Abstract ...
The presence of neutron flux coupled with fissioning component like helium-3 isotope creates at any point of space highly energetic particles. Their enormous energy was acquired from the transformation of strong interactions’ energy of fissioning nuclei to kinetic energy of produced particles. Their further evolution can not be resulted by Maxwell distribution due to the constant rate of their formation. Moreover, each fission fragment possesses its unique energy spectra function formed by the stopping media and the initial fragments’ energy. It also should be pointed out that transformation of strong interactions’ energy, maintained by gluons, into kinetic energy of fission fragments products can not take place without neutrino or antineutrino participation. Any radioactive decay, as well as any nuclear fissioning processes, are resulting in fast particles, among them - electrons and their immanent satellite antineutrino. Antineutrinos and neutrinos are spreading in all directions and berry all information about what’s going on within the reactor. In the present paper the typical fissioning process 32He + 10n → 1p + 31T + 0.76MeV is analyzed with accent at this problem. This fission reaction is unknown due to the variety of all possible transformations of quarks from one type to another. The very high intensity of strong interactions field makes it possible to transform its energy directly to mass creating in this case massive W +, W −, Z0 bosons which start breaking equilibrium within nuclei.
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| Sirojiddin Toshpulatov |
Country: Uzbekistan
| Presentation type: Without report
Organization: «O'zMU»
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| Saken Toktarbay |
Country: Kazakhstan
| Presentation type: Without report
Organization: «Al Farabi Kazakh National University»
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| Algis Malybayev |
Country: Kazakhstan
| Presentation type: Contributed talk
Presentation title: «On exact dyon-like black hole solutions in the model with two Abelian gauge fields and two scalar fields»
Organization: «Al-Farabi Kazakh National University»
May14|
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Abstract ...
Dilatonic black hole dyon-like solution in the gravitational 4d model with two scalar fields and two 2-forms, governed by two 2-dimensional dilatonic coupling vectors is found. Some physical parameters of the solutions are obtained: gravitational mass, scalar charge, Hawking temperature, black hole area entropy and parametrized post-Newtonian (PPN) parameters.
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| Gulmira Nurbahyt |
Country: Kazakhstan
| Presentation type: Without report
Organization: «Kazak national university after al-farabi»
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| Aigerim Abylayeva |
Country: Kazakhstan
| Presentation type: Without report
Organization: «KazNU named after al-Farabi»
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| Amankhan Talkhat |
Country: Kazakhstan
| Presentation type: Without report
Organization: «Al-farabi kazakh national university»
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| Gulnur Single |
Country: Kazakhstan
| Presentation type: Without report
Organization: «KazNU»
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| Aleksandra Demyanova |
Country: Узбекистан
| Presentation type: Plenary talk
Presentation title: «DYNAMICS OF CHARGED AND MAGNETIZED PARTICLES AROUND CYLINDRICAL BLACK HOLES IMMERSED IN EXTERNAL MAGNETIC FIELD»
Organization: «Ulugbek Astronomical Institute»
May13|
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Abstract ...
The motion and acceleration of an electrically charged and magnetized particle around a cylindrical black hole in the presence of an external asymptotically uniform mag netic field parallel to the z axis is investigated. We look at circular orbits around a central object and study the dependence of the most internal stable circular orbits (ISCO) on the so-called magnetic coupling parameters, which are responsible for the interaction between the external magnetic field and magnetized and charged particles. It is shown that the ISCO radius decreases with increasing magnetized parameter. Therefore, we also studied collisions of magnetized particles around a cylindrical black hole immersed in an external magnetic field, and showed that the magnetic field can act as a particle accelerator near non-rotating cylindrical black holes.
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| Dina Kairatkyzy |
Country: Kazakhstan
| Presentation type: Plenary talk
Presentation title: «Dark matter halo»
Organization: «Kazakh National University»
May13|
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Abstract ...
We usе twо suіtеs оf ultrа-hіgh rеsоlutіоn N-bоdy sіmulаtіоns Phоеnіx аnd Аquаrіus Prоjесts tо study thе аssеmbly hіstоry оf sub-hаlоs аnd іts dеpеndеnсе оn hоst hаlо mаss. Wе fоund thаt mоrе mаssіvе hаlоеs hаvе mоrе prоgеnіtоrs, whісh іs іn соntrаst wіth fоrmеr wоrks bесаusе thеy соuntеd dynаmісаl prоgеnіtоrs rеpеаtеdly. Lеss mаssіvе hаlоs hаvе lаrgеr frасtіоn оf dynаmісаl prоgеnіtоrs thаn mоrе mаssіvе оnеs. Thе typісаl ассrеtіоn tіmе dеpеnds strоngly оn hоst hаlо mаss. Prоgеnіtоrs оf gаlасtіс hаlоs аrе ассrеtеd аt hіghеr rеdshіft thаn thаt оf сlustеr hаlоs. Оnсе thеsе prоgеnіtоrs оrbіt thеіr prіmаry systеms, thеy rаpіdly lоsе thеіr оrіgіnаl mаss but nоt thеіr іdеntіfіеrs. Mоst оf thе prоgеnіtоrs аrе аblе tо survіvе tо prеsеnt dаy. Аt gіvеn rеdshіft, thе survіvаl frасtіоn оf ассrеtеd sub-hаlоs іs іndеpеndеnt оf hоst hаlо mаss, whіlе sub-hаlоs іn hіgh mаss hаlоs lоst mоrе mаss.
Іn the second part if our research we usе а sеmі-аnаlytісаl gаlаxy fоrmаtіоn mоdеl соmpіlеd оn а Mіllеnnіum Sіmulаtіоn tо study thе sіzе еvоlutіоn оf mаssіvе еаrly-typе gаlаxіеs frоm rеdshіft z = 2 tо prеsеnt dаys. Wе fіnd thаt thе mоdеl wе usеd іs аblе tо wеll rеprоduсе thе аmplіtudе аnd slоpе оf sіzе-mаss rеlаtіоn, аs wеll аs іts еvоlutіоn. Thе аmplіtudе оf thіs rеlаtіоn rеflесts thе typісаl соmpасtnеss оf dаrk mаttеr hаlоs аt thе tіmе whеn mоst stаrs аrе fоrmеd. Thіs lіnk bеtwееn sіzе аnd stаr fоrmаtіоn еpосh іs prоpаgаtеd іn thrоugh gаlаxy mergers. Mіnоr mergers аrе іnсrеаsіngly іmpоrtаnt wіth іnсrеаsіng prеsеnt dаy stеllаr mаss fоr gаlаxіеs mоrе mаssіvе thаn 1011.4M⊙. Аt lоwеr mаssеs, mаjоr mergers аrе mоrе іmpоrtаnt. Іn sіtu stаr fоrmаtіоn соntrіbutеs mоrе tо thе sіzе grоwth thаn іt dоеs tо stеllаr mаss grоwth. Sіmіlаr tо fоrmеr wоrks, wе fіnd thаt mіnоr mergers dоmіnаtе thе subsеquеnt grоwth bоth іn stеllаr mаss аnd іn sіzе fоr еаrly fоrmеd еаrly-typе gаlаxіеs.
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| Toshitaka Kajino |
Country: China/Japan
| Presentation type: Plenary talk
Presentation title: «Nucleosynthetic Evidence for Primordial & Stellar Black Holes and Binaries»
Organization: «Beihang University/National Astronomical Observatory of Japan,University of Tokyo»
May13|
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Abstract ...
The success of big-bang nucleosynthesis of the light elements and CMB anisotropies supports the standard cosmology, but the expected time variation of the light elemental abundances is thought to be a piece of evidence for the Hawking radiation from primordial black holes which operates over the entire history of cosmic evolution. Likewise, the standard scenario of element genesis indicates that the nucleosynthesis in the supernovae leaving neutron stars as remnants and the mergers of neutron stars or neutron star and black hole are the major source of gold, uranium and other heavy atomic nuclides. However, it has recently been found theoretically that the catastrophic collapse of very massive stars into the black holes and associated jets are the viable site for heavy element production. In this talk, we will discuss the recent progress in the nucleosynthesis theories and the roles of the primordial black holes and stellar black holes.
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| Sardor Tojiev |
Country: Uzbekistan
| Presentation type: Contributed talk
Presentation title: «Gauss-Bonnet boson stars»
Organization: «Ulugh Beg Astronomical Institute»
May13|
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Abstract ...
In this talk we will discuss construction of flat and asymptotically Anti-de Sitter (AdS) boson stars in (4+1)–dimensional Gauss–Bonnet gravity. We describe the dependence of the mass M , charge Q and radius R of the boson stars on the model parameters such as the Gauss–Bonnet coupling, the cosmological constant and the gravitational constant. The basic properties of boson star solutions have been investigated for different negative values of Gauss-Bonnet parameter.
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| Bakhtiyor Narzilloev |
Country: China
| Presentation type: Plenary talk
Presentation title: «Kerr-Taub-NUT spacetime to explain the energetics of black hole candidates.»
Organization: «Fudan university»
May14|
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Abstract ...
In the work we explain the radiative efficiency and the jet power of the selected black hole sources in point of view of the Kerr-Taub-NUT spacetime. We consider thin accretion disk model proposed by Novikov-Thorne to explain the radiative efficiency of the selected sources and Blanford and Znajeck mechanism to explain the transient jets of the black hole candidates.
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| Daniele Malafarina |
Country: Italy
| Presentation type: Plenary talk
Presentation title: «Properties of a class of black hole mimickers»
Organization: «Nazarbayev University»
May14|
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Abstract ...
We discuss the observational properties of a class of exact solutions of Einstein's field equations that posses naked singularities and describe exotic sources that can mimic black holes.
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| Luca Baiotti |
Country: Japan
| Presentation type: Plenary talk
Presentation title: «Gravitational waves from binary neutron stars»
Organization: «Osaka University»
May14|
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Abstract ...
I will review the current global status of research on gravitational waves emitted from mergers of binary neutron star systems, focussing on general-relativistic simulations and their use to interpret data from the gravitational-wave detectors, especially in relation to the equation of state of compact stars.
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| Farrukh Fattoyev |
Country: United States
| Presentation type: Plenary talk
Presentation title: «GW190814: Impact of a 2.6 solar mass neutron star on the nucleonic equations of state»
Organization: «Manhattan College, USA»
May12|
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Abstract ...
Is the secondary component of GW190814 the lightest black hole or the heaviest neutron star ever discovered in a double compact-object system [Abbott et al. Astrophys. J. 896, L44 (2020)]? In this talk, I give a nuclear physics perspective to answer this question. We employ covariant density functional theory that provides a unique framework to investigate both the properties of finite nuclei and neutron stars, while enforcing causality at all densities. By tuning existing energy density functionals we were able to: (i) account for a 2.6 solar mass neutron star, (ii) satisfy the original constraint on the tidal deformability of a 1.4 solar mass neutron star, and (iii) reproduce ground-state properties of finite nuclei. Yet, for the class of models explored in this work, we find that the stiffening of the equation of state required to support supermassive neutron stars is inconsistent with either constraints obtained from energetic heavy-ion collisions or from the low deformability of medium-mass stars. Thus, considering general relativity correct in the strong field regime, we speculate that the maximum neutron star mass can not be significantly higher than the existing observational limit and that the 2.6 solar mass compact object is likely to be the lightest black hole ever discovered.
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| Jutta Kunz |
Country: Germany
| Presentation type: Plenary talk
Presentation title: «Scalarized Black Holes»
Organization: «University of Oldenburg»
May12|
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Abstract ...
Black holes represent outstanding astrophysical laboratories to test the strong gravity regime, since alternative theories of gravity may predict black hole solutions whose may differ distinctly from those of General Relativity. When higher curvature terms are included in the gravitational action as, for instance, in the form of the Gauss-Bonnet term coupled to a scalar field, scalarized black holes result. Here we discuss several types of scalarized black holes.
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| Rustam Ibadov |
Country: Узбекистан
| Presentation type: Plenary talk
Presentation title: «The fundamental equation of the field theory in De Sitter pulse space»
Organization: «Samarkand State University»
May14|
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Abstract ...
The fundamental equation of the field theory in De Sitter pulse 5-dimensional space is obtained. The wave function, subordinated to this equation in usual space-time, doubles. One of these functions, probably to consider as the candidate on “the Phantom field” responsible for expansion of the Universe with acceleration. The Lagrangian of quantum electrodynamics with the fundamental mass is chosen as an effective interaction Lagrangian. All the calculations are made in the Euclidian space, the transfer to the ordinary pseudoeuclidian space is established in the final expressions only.The approach has been based on the assumption that the momentum space possesses the geometric structure of a de Sitters pace of constant curvature. A key role has been be assigned to this constant radius of curvature.
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| Ibrar Hussain |
Country: Pakistan
| Presentation type: Contributed talk
Presentation title: «Broken Lie Symmetries and the Energy Content of Some Charged Black Hole Spacetimes»
Organization: «National University of Sciences and Technology, Islamabad»
May12|
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Mass and charge of some black hole spacetimes are taken as small parameter and perturbed geodesic equations are constructed for them. Second-order approximate Lie symmetries are used to define the energy content of such spacetimes.
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| Sardor Murodov |
Country: Узбекистан
| Presentation type: Plenary talk
Presentation title: «Wormholе solutions in highеr curvаturе thеoriеs»
Organization: «Samarkand State University»
May14|
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Abstract ...
Wе considеr scаlаrizеd wormholеs with а Nеwmаn-Unti-Tаmburino chаrgе in both Еinstеin-scаlаr-Gаuss-Bonnеt аnd Еinstеin-scаlаr-Chеrn-Simons thеoriеs. By vаrying thе coupling pаrаmеtеr аnd thе scаlаr chаrgе wе dеtеrminе thе scаlаrizеd wormholе solutions, аnd thеir dеpеndеncе on thе Nеwmаn-Unti-Tаmburino chаrgе. Wе gеnеrаlizе thеsе scаlаrizеd wormholе solutions in two wаys. On thе onе hаnd, wе includе а Nеwmаn-Unti-Tаmburino chаrgе аnd on thе othеr hаnd wе considеr bеsidеs thе Gаuss-Bonnеt invаriаnt аlso thе Chеrn-Simons invаriаnt.
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| Z Yousaf |
Country: Pakistan
| Presentation type: Contributed talk
Presentation title: «The Measure of Complexity in Spherical Relativistic Geometry»
Organization: «University of the Punjab»
May12|
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Abstract ...
The aim of this paper is to generalize the definition of complexity for the static self-gravitating structure in f (R, T, Q) gravitational theory, where R is the Ricci scalar, T is the trace part of energy–momentum tensor, and Q ≡ RαβTαβ. In this context, we have considered locally anisotropic spherical matter distribution and calculated field equations and conservation laws. After the orthogonal splitting of the Riemann curvature tensor, we found the corresponding
complexity factor with the help of structure scalars. It is seen that the system may have zero complexity factor if the effects of energy density inhomogeneity and pressure anisotropy cancel the effects of each other.
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| Yuri Shtanov |
Country: Ukraine
| Presentation type: Plenary talk
Presentation title: «Constraints in inflationary magnetogenesis»
Organization: «Bogolyubov Institute for Theoretical Physics»
May13|
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Abstract ...
We discuss popular models of inflationary and early post-inflationary magnetogenesis and present model-independent upper bounds on the strength of the resulting magnetic fields imposed by the considerations of weak coupling, back-reaction and Schwinger effect.
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| Naresh Dadhich |
Country: India
| Presentation type: Plenary talk
Presentation title: «Higher dimensional rotating black holes cannot be formed by an accretion process»
Organization: «IUCAA, Pune»
May12|
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Abstract ...
Black holes are generally formed by collapse of a dust cloud under its own gravity or accretion of matter onto a gravitating center. For rotating black hole, cloud has to have some rotation which also contributes to gravitational potential producing repulsive component that counters attraction due to mass. In higher dimensions greater than four, non-zero angular momentum particles would always encounter potential barrier which is greater than particle's energy at infinity. Thus arises the critical question how does then a rotating black hole form in higher dimensions?
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| Wenbiao Han |
Country: China
| Presentation type: Plenary talk
Presentation title: «Testing propagation effects of gravitational waves»
Organization: «Shanghai Astronomical Observatory»
May12|
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Abstract ...
In general relativity, there is no dispersion in gravitational waves, while some modified gravity theories predict dispersion phenomena in the propagation of gravitational waves. This dispersion will induce an observable deviation of waveforms if the orbits have large eccentricities. The mechanism is that the waveform modes with different frequencies will be emitted at the same time due to the existence of eccentricity. During the propagation, because of the dispersion, the arrival time of different modes will be different, then produce the deviation and dephasing of waveforms compared with general relativity.
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| Cosimo Bambi |
Country: China
| Presentation type: Plenary talk
Presentation title: «Testing General Relativity with black hole X-ray data: recent progress and future developments»
Organization: «Fudan University»
May12|
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Abstract ...
The theory of General Relativity has successfully passed a large number of observational tests. The theory has been extensively tested in the weak-field regime with experiments in the Solar System and observations of binary pulsars. The past five years have seen significant advancements in the study of the strong-field regime, which can now be tested with gravitational waves, X-ray data, and mm Very Long Baseline Interferometry observations. In my talk, I will summarize the state-of-the-art of the tests of General Relativity with black hole X-ray data, discussing its recent progress and future developments.
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| Ahmadjon Abdujabbarov |
Country: Uzbekistan
| Presentation type: Contributed talk
Presentation title: «Optical properties of black hole»
Organization: «Ulugh Beg Astronimcal Institute / Shanghai Astronomical Observatory»
May12|
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Abstract ...
We discuss the gravitational lensing and shadow of black hole in defferent gravity models.
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| Martin Kolos |
Country: Czech Republic
| Presentation type: Contributed talk
Presentation title: «Charged particle motion in black hole magnetosphere»
Organization: «Institute of Physics, SU in Opava»
May13|
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Abstract ...
Long-range forces provided by gravitational and electromagnetic
interactions are of crucial importance for understanding of
astrophysical processes around black holes. In this presentation we
will try to compare different approaches to the problem of
electromagnetic field around black hole and then we will examine
charged particle dynamics in selected black hole magnetosphere models.
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| Турсынбек Ерназаров |
Country: Казахстан
| Presentation type: Without report
Organization: «КазНУ имени аль-Фараби»
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| Mubasher Jamil |
Country: China
| Presentation type: Plenary talk
Presentation title: «Gravitational lensing and shadows for some spherically symmetric black holes»
Organization: «Zhejiang University of Technology»
May13|
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Abstract ...
I will discuss the gravitational lensing for the Kiselev black hole and shadow for the spinning black hole in conformal massive gravity.
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| Bobomurat Ahmedov |
Country: Uzbekistan
| Presentation type: Plenary talk
Presentation title: «Development and Perspectives of Relativistic Astrophysics in Uzbekistan»
Organization: «Ulugh Beg Astronomical Institute»
May12|
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Abstract ...
I will discuss successful development and establishment
of scientific group specialized in general relativity and relativistic
astrophysics in Uzbekistan. Summary of scientific results performed on the study in Uzbekistan in relativistic astrophysics of compact gravitational objects will be provided.
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| Viktoriya Giryanskaya |
Country: USA
| Presentation type: Contributed talk
Presentation title: «The gravitational wave signal from core-collapse supernovae»
Organization: «Pennsylvania State University»
May13|
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Abstract ...
We study gravitational waves (GWs) from a set of two- and three-dimensional multi-group neutrino radiation hydrodynamic simulations of core-collapse supernovae (CCSNe). Our goal is to systematize the current knowledge about the post-bounce CCSN GW signal and recognize the templatable features that could be used by the ground-based laser interferometers. We demonstrate that starting from ~400ms after core bounce the dominant GW signal represents the fundamental quadrupole (l=2) oscillation mode (f-mode) of the proto-neutron star (PNS), which can be accurately reproduced by a linear perturbation analysis of the angle-averaged PNS profile. Before that, in the time interval between ~200 and ~400ms after bounce, the dominant mode has two radial nodes and represents a g-mode. We associate the high-frequency noise in the GW spectrograms above the main signal with p-modes, while below the dominant frequency there is an `excluded region' with very little power. Weak dependence of the dominant GW frequency on the progenitor mass motivates us to provide a simple fit for it as a function of time, which can be used as a prior when looking for CCSN candidates in the LIGO data.
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| Ernazar Abdikamalov |
Country: Kazakhstan
| Presentation type: Plenary talk
Presentation title: «Explosions of massive stars»
Organization: «Nazarbayev University»
May13|
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Abstract ...
Core-collapse supernovae are the powerful explosions of massive stars that happen at the end of their lives. They play an important role in the evolution of the universe, enriching galaxies with heavy elements and giving birth to neutron stars and, in some cases, black holes. Despite their importance, the exact details of how they explode remain uncertain. In this talk, I will review our current understanding of the explosion mechanism with a particular emphasis on the role of multi-dimensional hydrodynamic instabilities.
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| DR. RABIA SALEEM |
Country: Pakistan
| Presentation type: Contributed talk
Presentation title: «Study of Interacting Dark Sectors using Chevallier-Polarsky-Linder Type Parametrization»
Organization: «COMSATS University Islamabad, Lahore Campus»
May12|
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Abstract ...
The main focus of this paper is to investigate an interacting
phenomena between dark matter-dark energy within a non-flat FLRW
spacetime geometry bounded by a horizon with specific cut-off.
We assume an interaction term $Q(z)$ between two dark components of the
fluid and evaluate it analytically via physical quantities like energy
density and pressure. We constraint the model parameters and found specific
region of validity for these parameters. Considering ``Chevallier-Polarsky-Linder
type parametrization" of the coincidence parameter $r(z)$, we observed that our model
possess a future singularity of Type III. After finding the singular behavior, we examine
the nature of our model via cosmological parameters like $q,~r,~s$. It is noted that our model
is very close to $\Lambda$ cold dark matter model.
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| Zoha Tariq |
Country: Pakistan
| Presentation type: Plenary talk
Presentation title: «Effects of electromagnetic field on the structure of massive compact objects»
Organization: «University of the Punjab»
May12|
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Abstract ...
This paper encompasses a set of stellar equations that administer the formation and evolution of self-gravitating, dissipative spherically symmetric fluid distributions having anisotropic stresses in the presence of electromagnetic field. The Riemann tensor is split orthogonally to procure five scalar functions named as structure scalars which are then utilized in the stellar equations. It is shown that some basic fluid properties such as energy density inhomogeneity, pressure anisotropy and heat flux are interlinked with the obtained scalars. Further, it is shown that all the solutions to Einstein equations can be written in terms of these five scalars keeping in view the static case.
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| Muhammad Zaeem Ul Haq Bhatti |
Country: Pakistan
| Presentation type: Contributed talk
Presentation title: «Dynamical Analysis of Self-gravitating Objects in Modified Gravity»
Organization: «University of the Punjab»
May12|
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Abstract ...
This talk aims to analyze the generalization of Lemaitre-Tolman-Bondi (LTB) spacetime for dissipative dust under the influence of particular modified gravity. We explore the modified field equations, kinematical variables, and mass function in this scenario. We calculated the scalar functions coming from the orthogonal decomposition of the Riemann tensor in this framework. These scalar functions known as structure scalars have been explored for LTB spacetime using modified field equations. We found that generalized LTB spacetime has properties comparable with LTB and obtained structure scalars in both cases which have a similar dependence on a material profile even in modified gravity.
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