scholarly journals A Quasar-based Supermassive Black Hole Binary Population Model: Implications for the Gravitational Wave Background

2022 ◽  
Vol 924 (2) ◽  
pp. 93
Author(s):  
J. Andrew Casey-Clyde ◽  
Chiara M. F. Mingarelli ◽  
Jenny E. Greene ◽  
Kris Pardo ◽  
Morgan Nañez ◽  
...  

Abstract The nanohertz gravitational wave background (GWB) is believed to be dominated by GW emission from supermassive black hole binaries (SMBHBs). Observations of several dual-active galactic nuclei (AGN) strongly suggest a link between AGN and SMBHBs, given that these dual-AGN systems will eventually form bound binary pairs. Here we develop an exploratory SMBHB population model based on empirically constrained quasar populations, allowing us to decompose the GWB amplitude into an underlying distribution of SMBH masses, SMBHB number density, and volume enclosing the GWB. Our approach also allows us to self-consistently predict the number of local SMBHB systems from the GWB amplitude. Interestingly, we find the local number density of SMBHBs implied by the common-process signal in the NANOGrav 12.5-yr data set to be roughly five times larger than previously predicted by other models. We also find that at most ∼25% of SMBHBs can be associated with quasars. Furthermore, our quasar-based approach predicts ≳95% of the GWB signal comes from z ≲ 2.5, and that SMBHBs contributing to the GWB have masses ≳108 M ⊙. We also explore how different empirical galaxy–black hole scaling relations affect the local number density of GW sources, and find that relations predicting more massive black holes decrease the local number density of SMBHBs. Overall, our results point to the important role that a measurement of the GWB will play in directly constraining the cosmic population of SMBHBs, as well as their connections to quasars and galaxy mergers.

2009 ◽  
Vol 5 (S267) ◽  
pp. 270-270
Author(s):  
Z. L. Wen ◽  
J. L. Han ◽  
F. S. Liu

Galaxy mergers play an important role in many astrophysical processes, such as growth of massive galaxies, triggering AGN, formation of supermassive black hole (SMBH) binaries, and gravitational wave (GW) radiation. Merger rate is one of key quantities for these studies. Previous studies show that the pair fraction varies in a range of 1%–10% in the redshift range of z = 0.2–1.2. These merger rates are usually calculated from projected close pairs, and very few previous authors have carefully checked the merging fraction of a large sample of pairs.


2021 ◽  
Vol 503 (3) ◽  
pp. 3629-3642
Author(s):  
Colin DeGraf ◽  
Debora Sijacki ◽  
Tiziana Di Matteo ◽  
Kelly Holley-Bockelmann ◽  
Greg Snyder ◽  
...  

ABSTRACT With projects such as Laser Interferometer Space Antenna (LISA) and Pulsar Timing Arrays (PTAs) expected to detect gravitational waves from supermassive black hole mergers in the near future, it is key that we understand what we expect those detections to be, and maximize what we can learn from them. To address this, we study the mergers of supermassive black holes in the Illustris simulation, the overall rate of mergers, and the correlation between merging black holes and their host galaxies. We find these mergers occur in typical galaxies along the MBH−M* relation, and that between LISA and PTAs we expect to probe the full range of galaxy masses. As galaxy mergers can trigger star formation, we find that galaxies hosting low-mass black hole mergers tend to show a slight increase in star formation rates compared to a mass-matched sample. However, high-mass merger hosts have typical star formation rates, due to a combination of low gas fractions and powerful active galactic nucleus feedback. Although minor black hole mergers do not correlate with disturbed morphologies, major mergers (especially at high-masses) tend to show morphological evidence of recent galaxy mergers which survive for ∼500 Myr. This is on the same scale as the infall/hardening time of merging black holes, suggesting that electromagnetic follow-ups to gravitational wave signals may not be able to observe this correlation. We further find that incorporating a realistic time-scale delay for the black hole mergers could shift the merger distribution towards higher masses, decreasing the rate of LISA detections while increasing the rate of PTA detections.


2021 ◽  
Vol 30 (6) ◽  
pp. 20-29
Author(s):  
Young-Min KIM ◽  
Miok PARK ◽  
Yeong-Bok BAE ◽  
Sungwook E HONG ◽  
Chan PARK

Recently, many Nobel Prizes in Physics have been awarded in the field of astrophysics. Gravitational wave observations and contributions to LIGO in 2017, cosmology and exoplanets in 2019, and black hole formation theory and discovery of a supermassive black hole in 2020. Surprisingly, that these topics, which are somewhat distant from our daily life, have great physical significance and are being actively studied worldwide. We invited young astrophysicists at the forefront of astrophysic research to share their thoughts on astrophysics. That conversation took place online on June 2, 2021.


2017 ◽  
Vol 1 (12) ◽  
pp. 886-892 ◽  
Author(s):  
Chiara M. F. Mingarelli ◽  
T. Joseph W. Lazio ◽  
Alberto Sesana ◽  
Jenny E. Greene ◽  
Justin A. Ellis ◽  
...  

2019 ◽  
Vol 122 (11) ◽  
Author(s):  
Alexander C. Jenkins ◽  
Richard O‘Shaughnessy ◽  
Mairi Sakellariadou ◽  
Daniel Wysocki

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