Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userLimits on Runaway Growth of Intermediate Mass Black Holes from Advanced LIGO
124
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
There is growing evidence that intermediate-mass black holes (IMBHs), defined here as having a mass in the range M=500-10^5 Msun, are present in the dense centers of certain globular clusters (GCs). Gravitational waves (GWs) from their mergers with other IMBHs or with stellar BHs in the cluster are mostly emitted in frequencies <10 Hz, which unfortunately is out of reach for current ground-based observatories such as advanced LIGO (aLIGO). Nevertheless, we show that aLIGO measurements can be used to efficiently probe one of the possible formation mechanisms of IMBHs in GCs, namely a runaway merger process of stellar seed BHs. In this case, aLIGO will be sensitive to the lower-mass rungs of the merger ladder, ranging from the seed BH mass to masses >~50-300 Msun, where the background from standard mergers is expected to be very low. Assuming this generic IMBH formation scenario, we calculate the mass functions that correspond to the limiting cases of possible merger trees. Based on estimates for the number density of GCs and taking into account the instrumental sensitivity, we show that current observations do not effectively limit the occupation fraction f_occ of IMBHs formed by runaway mergers of stellar BHs in GCs. However, we find that a six-year run of aLIGO at design sensitivity will be able to probe down to f_occ<3% at a 99.9% confidence level, either finding evidence for this formation mechanism, or necessitating others if the fraction of GCs that harbor IMBHs is higher.
rate research
Read More
Observational evidence has been mounting for the existence of intermediate mass black holes (IMBHs, 10^2-10^5 Msun), but observing them at all, much less constraining their masses, is very challenging. In one theorized formation channel, IMBHs are the seeds for supermassive black holes in the early universe. As a result, IMBHs are predicted to exist in the local universe in dwarf galaxies, as well as wandering in more massive galaxy halos. However, these environments are not conducive to the accretion events or dynamical signatures that allow us to detect IMBHs. The Laser Interferometer Space Antenna (LISA) will demystify IMBHs by detecting the mergers of these objects out to extremely high redshifts, while measuring their masses with extremely high precision. These observations of merging IMBHs will allow us to constrain the formation mechanism and subsequent evolution of massive black holes, from the dark ages to the present day, and reveal the role that IMBHs play in hierarchical galaxy evolution.
Intermediate-mass black holes (IMBHs) span the approximate mass range $100$--$10^5,M_odot$, between black holes (BHs) formed by stellar collapse and the supermassive BHs at the centers of galaxies. Mergers of IMBH binaries are the most energetic gravitational-wave sources accessible by the terrestrial detector network. Searches of the first two observing runs of Advanced LIGO and Advanced Virgo did not yield any significant IMBH binary signals. In the third observing run (O3), the increased network sensitivity enabled the detection of GW190521, a signal consistent with a binary merger of mass $sim 150,M_odot,$ providing direct evidence of IMBH formation. Here we report on a dedicated search of O3 data for further IMBH binary mergers, combining both modelled (matched filter) and model independent search methods. We find some marginal candidates, but none are sufficiently significant to indicate detection of further IMBH mergers. We quantify the sensitivity of the individual search methods and of the combined search using a suite of IMBH binary signals obtained via numerical relativity, including the effects of spins misaligned with the binary orbital axis, and present the resulting upper limits on astrophysical merger rates. Our most stringent limit is for equal mass and aligned spin BH binary of total mass $200,M_odot$ and effective aligned spin 0.8 at $0.056,Gpc^{-3} yr^{-1}$ (90 $%$ confidence), a factor of 3.5 more constraining than previous LIGO-Virgo limits. We also update the estimated rate of mergers similar to GW190521 to $0.08, Gpc^{-3}yr^{-1}$.
The NSFs Karl G. Jansky Very Large Array (VLA) was used at 3~cm to search for accretion signatures from intermediate-mass black holes (IMBHs) in 19 globular star clusters (GCs) in NGC,3115, an early-type galaxy at a distance of 9.4 Mpc. The 19 have stellar masses $M_{star} sim (1.1 - 2.7) times 10^6~M_odot$, with a mean $overline{M_{star}} sim 1.8 times 10^6~M_odot$. None were detected. An IMBH accretion model was applied to the individual GCs and their radio stack. The radio-stacked GCs have an IMBH mass $overline{M_{rm IMBH}} < 1.7 times 10^5~M_odot$ and mass fraction $overline{M_{rm IMBH}} / overline{M_{star}} < 9.5%$, with each limit being uncertain by a factor of about 2.5. The latter limit contrasts with the extremes of some stripped nuclei, suggesting that the set of stacked GCs in NGC,3115 is not a set of such nuclei. The radio luminosities of the individual GCs correspond to X-ray luminosities $L_{rm X} < (3.3 - 10) times 10^{38}$ erg~s$^{-1}$, with a factor of about 2.5 uncertainty. These limits predicted for putative IMBHs in the GCs are consistent with extant {em Chandra} observations. Finally, a simulated observation with a next-generation VLA (ngVLA) demonstrates that accretion signatures from IMBHs in GCs can be detected in a radio-only search, yet elude detection in an X-ray-only search due to confusion from X-ray binaries in the GCs.
The recent detection by Advanced LIGO of gravitational waves (GW) from the merging of a binary black hole system sets new limits on the merging rates of massive primordial black holes (PBH) that could be a significant fraction or even the totality of the dark matter in the Universe. aLIGO opens the way to the determination of the distribution and clustering of such massive PBH. If PBH clusters have a similar density to the one observed in ultra-faint dwarf galaxies, we find merging rates comparable to aLIGO expectations. Massive PBH dark matter predicts the existence of thousands of those dwarf galaxies where star formation is unlikely because of gas accretion onto PBH, which would possibly provide a solution to the missing satellite and too-big-to-fail problems. Finally, we study the possibility of using aLIGO and future GW antennas to measure the abundance and mass distribution of PBH in the range [5 - 200] Msun to 10% accuracy.
Ultra-Luminous X-ray sources (ULXs) are accreting black holes for which their X-ray properties have been seen to be different to the case of stellar-mass black hole binaries. For most of the cases their intrinsic energy spectra are well described by a cold accretion disc (thermal) plus a curved high-energy emission components. The mass of the black hole (BH) derived from the thermal disc component is usually in the range of 100-10^5 solar masses, which have led to the idea that this can represent strong evidence of the Intermediate Mass Black Holes (IMBH), proposed to exist by theoretical studies but with no firm detection (as a class) so far. Recent theoretical and observational developments are leading towards the idea that these sources are instead compact objects accreting at an unusual super-Eddington regime instead. On the other hand, gravitational waves have been seen to be a useful tool for finding (some of these) IMBHs. We give a brief overview about the recent advent of the discovery of gravitational waves and their relationship with these so far elusive IMBHs.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
