Bulletin of the American Physical Society
APS April Meeting 2021
Volume 66, Number 5
Saturday–Tuesday, April 17–20, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session H09: Formation and Growth of Black HolesLive
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Sponsoring Units: DAP Chair: David Neilsen, BYU |
Sunday, April 18, 2021 10:45AM - 10:57AM Live |
H09.00001: XMM-SERVS: A Sensitive XMM-Newton Survey of the LSST Deep-Drilling Fields William Brandt, Qingling Ni Cosmic X-ray surveys over the past two decades have played a critical role in transforming our understanding of growing supermassive black holes (SMBHs) in the distant universe. I will describe one key program now advancing this effort, the 12 deg$^2$ XMM-SERVS survey, which is covering three legacy sky regions at 50 ks depth: the SERVS areas of CDF-S, XMM-LSS, and ELAIS-S1. These regions have first-rate multiwavelength coverage already and are LSST/DES deep-drilling fields, MOONS/PFS massive spectroscopy fields, prime TolTEC/ALMA fields, and multi-object reverberation mapping fields. When the survey and the follow-up of its 11,000 X-ray sources are complete, XMM-SERVS should dramatically advance studies of SMBH growth across the full range of cosmic environments, links between SMBH accretion and host-galaxy properties, groups/clusters at $z$ = 0.1-2, protoclusters, and other topics. I will also briefly describe a few prospects for advancing the X-ray surveys field with aggressive new projects. [Preview Abstract] |
Sunday, April 18, 2021 10:57AM - 11:09AM Live |
H09.00002: Discriminating Accretion States via Rotational Symmetry in Simulated Polarimetric Images of M87 Daniel Palumbo, George Wong, Benjamin Prather Polarized images of black holes have the potential to convey information about magnetic field morphology on event horizon scales. We describe a modal decomposition of linear polarized images into basis functions with varying polarization around a ring. We apply this decomposition to analyze ray traced images of general relativistic magnetohydrodynamics simulations of the Messier 87* (M87*) accretion flow. We show that the dimensionless Fourier coefficient associated with rotational symmetry, $\beta_2$, is a strong discriminator between accretion states for models of M87* that are consistent with the total intensity images produced by the Event Horizon Telescope (EHT). For simulated images viewed at the resolution of the EHT, we find that $|\beta_2|$ is greater than $0.2$ only for models with dynamically important magnetic fields in the accretion flow. We also find that higher black hole spins produce increasingly radial polarization patterns. [Preview Abstract] |
Sunday, April 18, 2021 11:09AM - 11:21AM Live |
H09.00003: A quantum mechanical model of a gravastar: Black hole without singularity Baljeet Lotte, Subodha Mishra A degenerate system of N-self gravitating fermions, when undergoes gravitational collapse can form a Schwarzschild-like black hole having no singularity at the center but with an event horizon at the Schwarzschild radius. We formulate this quantum mechanical model of the gravastar, by choosing a single particle trial density in the Thomas-Fermi approach and also using the uncertainty relation by special relativizing the Newtonian quantum gravity. We derive the exact ground state energy of a system of N self-gravitating fermionic particles, corrections to Schwarzschild radius, and Hawking temperature. In GTR the Buchdahl limit is associated with the central singularity, though in the post-Newtonian approximation of GTR, there is no such limit. It is interesting to note that in our quantum mechanical model of the gravastar as a compact object, no Buchdahl limit exists with or without the post-Newtonian approximation. REFERENCES: S. Mishra and B. K. Lotte. Mod. Phys. Lett. A 33,1850178 (2018). B. K. Lotte and S. Mishra, Mod. Phys. Lett. A 35, 2050081(2020). S. W. Hawking, Commun. Math. Phys. 43, 199 (1975). [Preview Abstract] |
Sunday, April 18, 2021 11:21AM - 11:33AM Live |
H09.00004: Relativistic Bondi accretion for stiff equations of state Chloe Richards, Thomas Baumgarte, Stuart Shapiro We revisit Bondi accretion - steady-state, adiabatic, spherical gas flow onto a Schwarzschild black hole at rest in an asymptotically homogeneous medium - for stiff polytropic equations of state (EOSs) with adiabatic indices $\Gamma > 5/3$. A general relativistic treatment is required to determine their accretion rates, for which we provide exact expressions. We discuss several qualitative differences between results for soft and stiff EOSs - including the appearance of a minimum steady-state accretion rate for EOSs with $\Gamma \geq 5/3$ - and explore limiting cases in order to examine these differences. Our results are useful, for example, to estimate the accretion rate onto a mini-black hole residing at the center of a neutron star. [Preview Abstract] |
Sunday, April 18, 2021 11:33AM - 11:45AM Live |
H09.00005: The Carafe Galaxy: A Wet Merger Remnant With a Supermassive Binary Black Hole Precursor Prajval Shastri, M N Sundar, Lalitha Sairam, P T Rahna, Brent Groves, John Hutchings, Jayant Murthy We have been carrying out a multi-wavelength investigation of the footprints of feedback from accreting supermassive black holes in active galaxies at redshifts \textasciitilde 0, known as the Siding Spring Southern Seyfert Spectroscopic Snap-Shot Survey (S7). Among our sample objects is the Carafe galaxy, which is long known to be a wet merger remnant. The core of the Carafe has two regions with emission-line signatures of active galactic nuclei, as confirmed by our IFU (WiFeS) data cubes from the Siding Spring 2.3m telescope. From ATCA measurements we find that the radio emission from these purported AGN, though unresolved, is synchrotron emission. With Chandra imaging we are able detect compact hard x-ray emission from both these regions, which concurs with the hypothesis that this system has an accreting binary black hole precursor. We have also observed the Carafe with the the Indian multi-frequency satellite ASTROSAT, which gives us an ultraviolet image of the galaxy with unprecedented resolution. Preliminary analysis suggest that the binary precursor is below the detection limit suggestive of heavy extinction in the heart of the Carafe. [Preview Abstract] |
Sunday, April 18, 2021 11:45AM - 11:57AM Live |
H09.00006: 3D-GRMHD Simulations of Binary Supermassive Black Holes: Light curves and behavior during inspiral Mark Avara, Dennis Bowen, Manuela Campanelli, Scott Noble, Julian Krolik, Vassilios Mewes While many promising candidate accreting binary supermassive black hole systems have been identified, more comprehensive and realistic physical models of these systems will be necessary to confirm their identity. Unfortunately, the large range of temporal and physical scales have made their simulation in full 3D-MHD prohibitive. Here we present new 3D-GRMHD simulations that extend to 10s of binary orbits in duration, made possible via the enhanced numerical efficiencies of the multi-mesh/multi-physics code PatchworkMHD. These simulations demonstrate a number of key advances capturing realistic physical behavior including evolution of the entire central cavity and resolving the black hole horizons where acceleration of jets and winds can occur due to black hole spin. We report unexpected 3D hydrodynamical behavior, the evolution and importance of magnetic fields, and early results from radiative post-processing which provides spectra and light curves. Finally, we describe our next steps towards a future database of synthetic light curves, images, and spectra that can be used with new observational resources, especially in the time-domain, to confirm the identity of supermassive black hole binaries and fix those systems as a cornerstone in the multi-messenger era. [Preview Abstract] |
Sunday, April 18, 2021 11:57AM - 12:09PM Live |
H09.00007: An Upper Limit on the Spin of SgrA* Based on Stellar Orbits in Its Vicinity. Giacomo Fragione The spin of the massive black hole (BH) at the center of the Milky Way, SgrA*, has been poorly constrained so far. We place an upper limit on the spin of SgrA* based on the spatial distribution of the S-stars, which are arranged in two almost edge-on disks that are located at a position angle of approximately $+$/- 45 degrees with respect to the Galactic plane, on a milliparsec scale around the Galactic center. Requiring that the frame-dragging precession has not had enough time to make the S-star orbital angular momentum precess, the spin of the massive BH at the center of the Milky Way can be constrained to \textless 0.1. [Preview Abstract] |
Sunday, April 18, 2021 12:09PM - 12:21PM Live |
H09.00008: Mass Determination Of Black Hole HMXB : IC 10 X-1 Sayantan Bhattacharya, Andre-Nicolas Chene, Ankur Roy, Rigel C. Cappallo, Silas G. T. Laycock, Dimitris M. Christodoulou IC 10 X-1 is a high mass X-ray binary (HMXB) that consists of a black hole (BH) and a Wolf-Rayet (WR) star with an orbital period of 34.9 hours. In a series of Chandra and XMM-Newton observations, eclipses were discovered with a duration of $\approx$ 5 hours. The source shows consistent variability around an X-ray luminosity of 7$\times$10$^{37}$ erg~s$^{-1}$, in which the optical radial-velocity (RV) measurements from the He~II line showed a phase shift compared to the X-ray ephemeris of the eclipse. This observation put in question the mass determination of the BH---either the He II line originates in a shadowed region of the stellar wind (hence it does not trace directly the motion of the WR star), or the BH is eclipsed by a trailing shock or plume. A shock front must be forming where the WR wind collides with wind emanating from the BH and its accretion disk. We are using archival optical spectra in order to generate RV plots from other lines originating deeper inside the WR photosphere and compare them to those obtained from the CMFGEN model. This investigation will lead to a more accurate determination of the BH mass in this HMXB system. [Preview Abstract] |
Sunday, April 18, 2021 12:21PM - 12:33PM Live |
H09.00009: Numerically modeling stochastic inflation and consequences for primordial black hole formation Rafid Mahbub, Aritra De Here I will talk about numerically modeling stochastic inflation in slow-roll and beyond. Stochastic inflation takes into account the influence of sub horizon quantum fluctuations of the inflaton which constantly become super horizon and modify the background inflaton dynamics. I will talk about how to numerically model these quantum kicks as Gaussian white noise without resorting to slow-roll approximations and compute the curvature power spectrum $\mathcal{P}_{\zeta}$. We see that, for ultra slow-roll models, there is an added enhancement of the order $\mathcal{O}(10)$ due to quantum diffusion domination. Further, I will explore the formation of primordial black holes (PBHs) under the stochastic inflation paradigm. We see that, even though there is an added enhancement in $\mathcal{P}_{\zeta}$, standard techniques for computing the PBH abundance does not capture the tail of the formation fraction. Stochastic inflation necessarily introduces an exponential tail to the distribution which increases PBH abundance. [Preview Abstract] |
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