Pulsars, transients and relativistic astrophysics

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Flaring Masers and Pumping

Proceedings of the International Astronomical Union Cambridge University Press (CUP) 18:S380 (2022) 422-429

Authors:

MD Gray, S Etoka, B Pimpanuwat, AMS Richards, FJ Cowie

Abstract:

AbstractWe briefly consider the history of maser variability, and of flaring variability specifically. We consider six proposed flare generation mechanisms, and model them computationally with codes that include saturation and 3-D structure (the last mechanism is modelled in 1-D). Fits to observational light curves have been made for some sources, and we suggest that a small number of observational parameters can diagnose the flare mechanism in many cases. The strongest flares arise from mechanisms that can increase the number density of inverted molecules in addition to by geometrical effects, and in events where unsaturated quiescent masers become saturated during the flare.
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The Birth of a Relativistic Jet Following the Disruption of a Star by a Cosmological Black Hole

(2022)

Authors:

Dheeraj R Pasham, Matteo Lucchini, Tanmoy Laskar, Benjamin P Gompertz, Shubham Srivastav, Matt Nicholl, Stephen J Smartt, James CA Miller-Jones, Kate D Alexander, Rob Fender, Graham P Smith, Michael D Fulton, Gulab Dewangan, Keith Gendreau, Eric R Coughlin, Lauren Rhodes, Assaf Horesh, Sjoert van Velzen, Itai Sfaradi, Muryel Guolo, N Castro Segura, Aysha Aamer, Joseph P Anderson, Iair Arcavi, Sean J Brennan, Kenneth Chambers, Panos Charalampopoulos, Ting-Wan Chen, A Clocchiatti, Thomas de Boer, Michel Dennefeld, Elizabeth Ferrara, Lluis Galbany, Hua Gao, James H Gillanders, Adelle Goodwin, Mariusz Gromadzki, M Huber, Peter G Jonker, Manasvita Joshi, Erin Kara, Thomas L Killestein, Peter Kosec, Daniel Kocevski, Giorgos Leloudas, Chien-Cheng Lin, Raffaella Margutti, Seppo Mattila, Thomas Moore, Tomas Muller-Bravo, Chow-Choong Ngeow, Samantha Oates, Francesca Onori, Yen-Chen Pan, Miguel Perez-Torres, Priyanka Rani, Ronald Remillard, Evan J Ridley, Steve Schulze, Xinyue Sheng, Luke Shingles, Ken W Smith, James Steiner, Richard Wainscoat, Thomas Wevers, Sheng Yang
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A numerical study of stellar discs in galactic nuclei

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) (2022)

Authors:

Taras Panamarev, Bence Kocsis

Abstract:

Abstract We explore the dynamics of stellar discs in the close vicinity of a supermassive black hole (SMBH) by means of direct N-body simulations. We show that an isolated nuclear stellar disc exhibits anisotropic mass segregation meaning that massive stars settle to lower orbital inclinations and more circular orbits than the light stars. However, in systems in which the stellar disc is embedded in a much more massive isotropic stellar cluster, anisotropic mass segregation tends to be suppressed. In both cases, an initially thin stellar disc becomes thicker, especially in the inner parts due to the fluctuating anisotropy in the spherical component. We find that vector resonant relaxation is quenched in the disc by nodal precession, but it is still the most efficient relaxation process around SMBHs of mass 106 M⊙ and above. Two body relaxation may dominate for less massive SMBHs found in dwarf galaxies. Stellar discs embedded in massive isotropic stellar clusters ultimately tend to become isotropic on the local two-body relaxation time-scale. Our simulations show that the dynamics of young stars at the centre of the Milky Way is mostly driven by vector resonant relaxation leading to an anticorrelation between the scatter of orbital inclinations and distance from the SMBH. If the S-stars formed in a disc less than 10 Myr ago, they may coexist with a cusp of stellar mass black holes or an intermediate mass black hole with mass up to 1000 M⊙ to reproduce the observed scatter of angular momenta.
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The rise and fall of the iron-strong nuclear transient PS16dtm

(2022)

Authors:

T Petrushevska, G Leloudas, D Ilic, M Bronikowski, P Charalampopoulos, GK Jaisawal, E Paraskeva, M Pursiainen, N Rakic, S Schulze, K Taggart, CK Wedderkopp, JP Anderson, T de Boer, K Chambers, TW Chen, G Damljanovic, M Fraser, H Gao, A Gomboc, M Gromadzki, N Ihanec, K Maguire, B Marcun, TE Muller-Bravo, M Nicholl, F Onori, TM Reynolds, SJ Smartt, J Sollerman, KW Smith, T Wevers, L Wyrzykowski
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Comprehensive coverage of particle acceleration and kinetic feedback from the stellar mass black hole V404 Cygni

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 518:1 (2022) 1243-1259

Authors:

RP Fender, KP Mooley, SE Motta, JS Bright, DRA Williams, AP Rushton, RJ Beswick, JCA Miller-Jones, M Kimura, K Isogai, T Kato
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