Black Hole density

  • B
  • Thread starter wolram
  • Start date
  • #1
wolram
Gold Member
4,267
555

Main Question or Discussion Point

It seems by this paper that there are more black holes than expected, so what is the expected density of black holes in the nearby universe?

arXiv:1606.04996 (cross-list from gr-qc) [pdf, other]
Constraining modified theories of gravity with gravitational wave stochastic background
Andrea Maselli, Stefania Marassi, Valeria Ferrari, Kostas Kokkotas, Raffaella Schneider
Comments: 5 pages, 4 figures
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE)

The direct discovery of gravitational waves has finally opened a new observational window on our Universe, suggesting that the population of coalescing binary black holes is larger than previously expected. These sources produce an unresolved background of gravitational waves, potentially observables by ground-based interferometers. In this paper we investigate how modified theories of gravity, modeled using the ppE formalism, affect the expected signal, and analyze the detectability of the resulting stochastic background by current and future ground-based interferometers. We find the constraints that AdLIGO would be able to set on modified theories, showing that they may significantly improve the current bounds obtained from astrophysical observations of binary pulsars.
 

Answers and Replies

  • #2
Chalnoth
Science Advisor
6,195
442
It seems by this paper that there are more black holes than expected, so what is the expected density of black holes in the nearby universe?

arXiv:1606.04996 (cross-list from gr-qc) [pdf, other]
Constraining modified theories of gravity with gravitational wave stochastic background
Andrea Maselli, Stefania Marassi, Valeria Ferrari, Kostas Kokkotas, Raffaella Schneider
Comments: 5 pages, 4 figures
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE)

The direct discovery of gravitational waves has finally opened a new observational window on our Universe, suggesting that the population of coalescing binary black holes is larger than previously expected. These sources produce an unresolved background of gravitational waves, potentially observables by ground-based interferometers. In this paper we investigate how modified theories of gravity, modeled using the ppE formalism, affect the expected signal, and analyze the detectability of the resulting stochastic background by current and future ground-based interferometers. We find the constraints that AdLIGO would be able to set on modified theories, showing that they may significantly improve the current bounds obtained from astrophysical observations of binary pulsars.
This isn't an experimental paper. They're running simulations on what Advanced LIGO might be able to detect in the future.

The statement in the first sentence is just the statement that because we have detected the merger of some intermediate-mass black holes (which were theorized but not known to exist until now), there may be quite a few black holes out there. The difficulty is that it's not really possible to say how many such black holes there are with a sample size of two. Give it a few years.
 
Top