Supermassive Black Hole Binaries: The Search Continues

Bogdanović, Tamara

doi:10.1007/978-3-319-10488-1_9

Cited by 43 publications

(25 citation statements)

References 167 publications

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“…Observations suggest that astrophysical black holes are generally spinning [1][2][3] and can form binary systems [4]. Spinning binary black holes (BBHs) are a promising source of gravitational waves (GWs) [5][6][7] for current and future detectors [8][9][10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Multi-timescale analysis of phase transitions in precessing black-hole binaries

et al. 2015

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The dynamics of precessing binary black holes (BBHs) in the post-Newtonian regime has a strong timescale hierarchy: the orbital timescale is very short compared to the spin-precession timescale which, in turn, is much shorter than the radiation-reaction timescale on which the orbit is shrinking due to gravitational-wave emission. We exploit this timescale hierarchy to develop a multiscale analysis of BBH dynamics elaborating on the analysis of Kesden et al. [Phys. Rev. Lett. 114, 081103 (2015)]. We solve the spin-precession equations analytically on the precession time and then implement a quasiadiabatic approach to evolve these solutions on the longer radiation-reaction time. This procedure leads to an innovative "precession-averaged" post-Newtonian approach to studying precessing BBHs. We use our new solutions to classify BBH spin precession into three distinct morphologies, then investigate phase transitions between these morphologies as BBHs inspiral. These precession-averaged post-Newtonian inspirals can be efficiently calculated from arbitrarily large separations, thus making progress towards bridging the gap between astrophysics and numerical relativity.

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Section: Introductionmentioning

confidence: 99%

Multi-timescale analysis of phase transitions in precessing black-hole binaries

et al. 2015

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“…With typical velocity offsets of ∼ 1000 km s −1 , searches are typically sensitive to systems with mass M ∼ 10 8 M separated by ∼ 0.1 pc and with orbital periods of ∼ 300 years. They will therefore only capture a fraction of an orbital cycle and other astrophysical processes, such as an orbiting hotspot produced by a local instability in the broad line region (BLR) of a galaxy or outflows associated with the accretion disk, may still be responsible for any effect seen (Bogdanović 2015;Barth et al 2015).…”

Section: Introductionmentioning

confidence: 99%

A systematic search for close supermassive black hole binaries in the Catalina Real-time Transient Survey

Graham

Djorgovski

Stern

et al. 2015

Mon. Not. R. Astron. Soc.

286

291

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Hierarchical assembly models predict a population of supermassive black hole (SMBH) binaries. These are not resolvable by direct imaging but may be detectable via periodic variability (or nanohertz frequency gravitational waves). Following our detection of a 5.2 year periodic signal in the quasar PG 1302-102 (Graham et al. 2015), we present a novel analysis of the optical variability of 243,500 known spectroscopically confirmed quasars using data from the Catalina Real-time Transient Survey (CRTS) to look for close (< 0.1 pc) SMBH systems. Looking for a strong Keplerian periodic signal with at least 1.5 cycles over a baseline of nine years, we find a sample of 111 candidate objects. This is in conservative agreement with theoretical predictions from models of binary SMBH populations. Simulated data sets, assuming stochastic variability, also produce no equivalent candidates implying a low likelihood of spurious detections. The periodicity seen is likely attributable to either jet precession, warped accretion disks or periodic accretion associated with a close SMBH binary system. We also consider how other SMBH binary candidates in the literature appear in CRTS data and show that none of these are equivalent to the identified objects. Finally, the distribution of objects found is consistent with that expected from a gravitational wave-driven population. This implies that circumbinary gas is present at small orbital radii and is being perturbed by the black holes. None of the sources is expected to merge within at least the next century. This study opens a new unique window to study a population of close SMBH binaries that must exist according to our current understanding of galaxy and SMBH evolution.

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“…Galaxy collisions and the subsequent coalescence of binary black holes explain galaxy/black hole growth and black hole activity (Sesana et al, 2011;Bogdanović, 2015). Strong gravitational wave signals occur during the final phase of the merging process (see the detection of gravitational waves from binary stellar sources by the LIGO and Virgo collaborations Abbott et al, 2016) and might be detected with Pulsar Timing Arrays (e.g.…”

Section: Introductionmentioning

confidence: 99%

The Milky Way’s Supermassive Black Hole: How Good a Case Is It?

Eckart

Hüttemann²,

Kiefer³

et al. 2017

Found Phys

122

105

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The compact and, with 4.3±0.3×106 M ⊙ , very massive object located at the center of the Milky Way is currently the very best candidate for a supermassive black hole (SMBH) in our immediate vicinity. The strongest evidence for this is provided by measurements of stellar orbits, variable X-ray emission, and strongly variable polarized near-infrared emission from the location of the radio source Sagittarius A* (SgrA*) in the middle of the central stellar cluster. Simultaneous near-infrared and X-ray observations of SgrA* have revealed insights into the emission mechanisms responsible for the powerful near-infrared and X-ray flares from within a few tens to one hundred Schwarzschild radii of such a putative SMBH at the center of the Milky Way. If SgrA* is indeed a SMBH it will, in projection onto the sky, have the largest event horizon and will certainly be the first and most important target of the Event Horizon Telescope (EHT) Very Long Baseline Interferometry (VLBI) observations currently being prepared. These observations in combination with the infrared interferometry experiment GRAVITY at the Very Large Telescope Interferometer (VLTI) and other experiments across the electromagnetic spectrum might yield proof for the presence of a black hole at the center of the Milky Way. The large body of evidence continues to discriminate the identification of SgrA* as a SMBH from alternative possibilities. It is, however, unclear when the ever mounting evidence for SgrA* being associated with a SMBH will suffice as a convincing proof. Additional compelling evidence may come from future gravitational wave observatories. This manuscript reviews the observational facts, theoretical grounds and conceptual aspects for the case of SgrA* being a black hole. We treat theory and observations in the framework of the philosophical discussions about "(Anti)Realism and Underdetermination", as this line of arguments allows us to describe the situation in observational astrophysics with respect to supermassive black holes. Questions concerning the existence of supermassive black holes and in particular SgrA* are discussed using causation as an indispensable element. We show that the results of our investigation are convincingly mapped out by this combination of concepts.

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Supermassive Black Hole Binaries: The Search Continues

Cited by 43 publications

References 167 publications

Multi-timescale analysis of phase transitions in precessing black-hole binaries

Multi-timescale analysis of phase transitions in precessing black-hole binaries

A systematic search for close supermassive black hole binaries in the Catalina Real-time Transient Survey

The Milky Way’s Supermassive Black Hole: How Good a Case Is It?

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