On the formation of compact, massive subsystems in stellar clusters and its relation with intermediate-mass black holes

Sedda, Manuel Arca

doi:10.1093/mnras/stv2265

Cited by 46 publications

(34 citation statements)

References 101 publications

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“…The difference in the values of M/L that we find here with respect to those by de Vita et al (2016) is in line with the difference among the global values of M/L listed in Table 3. Arca-Sedda (2016) proposed an analysis of numerical simulations showing that the excess of mass in the centre of a cluster could be due to the presence of a subsystem of heavy remnants orbitally segregated, and not to an IMBH. In particular, for the globular cluster ω Cen they estimate a mass of (1.45 ± 0.03) × 10 3 M ⊙ for the central component of massive remnants, assuming a total mass of 2.5 × 10 6 M ⊙ for the cluster.…”

Section: Comparison With Previous Workmentioning

confidence: 99%

The effect of stellar-mass black holes on the central kinematics of ω Cen: a cautionary tale for IMBH interpretations

Zocchi

Gieles

Hénault-Brunet

2018

Monthly Notices of the Royal Astronomical Society

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The search for intermediate-mass black holes (IMBHs) in the centre of globular clusters is often based on the observation of a central cusp in the surface brightness profile and a rise towards the centre in the velocity dispersion profiles. Similar signatures, however, could result from other effects, that need to be taken into account in order to determine the presence (or the absence) of an IMBH in these stellar systems. Following our previous exploration of the role of radial anisotropy in shaping these observational signatures, we analyse here the effects produced by the presence of a population of centrally concentrated stellar-mass black holes. We fit dynamical models to ω Cen data, and we show that models with ∼ 5% of their mass in black holes (consistent with ∼ 100% retention fraction after natal kicks) can reproduce the data. When simultaneously considering both radial anisotropy and mass segregation, the bestfit model includes a smaller population of remnants, and a less extreme degree of anisotropy with respect to the models that include only one of these features. These results underline that before conclusions about putative IMBHs can be made, the effects of stellar-mass black holes and radial anisotropy need to be properly accounted for.

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Section: Comparison With Previous Workmentioning

confidence: 99%

The effect of stellar-mass black holes on the central kinematics of ω Cen: a cautionary tale for IMBH interpretations

Zocchi

Gieles

Hénault-Brunet

2018

Monthly Notices of the Royal Astronomical Society

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“…Pasham et al, 2014;Wrobel et al, 2016;Earnshaw et al, 2016;Arca-Sedda, 2016). Kiziltan et al (2017) found an indirect evidence for an IMBH of about 2200 M ⊙ at the center of the globular cluster 47 Tucanae based on the dynamical state constrained by the timing data of millisecond pulsars.…”

Section: Working Definition Of a (Supermassive) Black Holementioning

confidence: 99%

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

Eckart

Hüttemann²,

Kiefer³

et al. 2017

Found Phys

123

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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“…Yokoyama 1997;Düchting 2004), or from runaway stellar collisions (e.g. Giersz et al 2015;Arca-Sedda 2016), or as the remnants of population III stars (e.g. Ricotti 2016) for example and how they are fuelled (from stellar winds, via Bondi accretion, or from Roche lobe overflow, for example Miller & Hamilton 2002;Miller & Colbert 2004).…”

Section: Introductionmentioning

confidence: 99%

Understanding the environment around the intermediate mass black hole candidate ESO 243-49 HLX-1

Webb

Guérou

Ciambur

et al. 2017

A&A

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Aims. ESO 243-49 HLX-1, otherwise known as HLX-1, is an intermediate mass black hole (IMBH) candidate located 8 (3.7 Kpc) from the centre of the edge-on S0 galaxy ESO 243-49. How the black hole came to be associated with this galaxy, and the nature of the environment in which it resides, remain unclear. Using multi-wavelength observations we aim to investigate the nature of the medium surrounding HLX-1, search for evidence of past mergers with ESO 243-49 and constrain parameters of the galaxy, including the mass of the expected central supermassive black hole, essential for future modelling of the interaction of the IMBH and ESO 243-49. Methods. We have reduced and analysed integral field unit observations of ESO 243-49 that were taken with the MUSE instrument on the VLT. Using complementary multi-wavelength data, including X-shooter, HST, Swift, Chandra and ATCA data, we have further examined the vicinity of HLX-1. We additionally examined the nature of the host galaxy and estimate the mass of the central supermassive black hole in ESO 243-49 using (black hole mass)-(host spheroid) scaling relations and the fundamental plane of black hole activity. Results. No evidence for a recent minor-merger that could result in the presence of the IMBH is discerned, but the data are compatible with a scenario in which minor mergers may have occurred in the history of ESO 243-49. The MUSE data reveal a rapidly rotating disc in the centre of the galaxy, around the supermassive black hole. The mass of the supermassive black hole at the centre of ESO 243-49 is estimated to be 0.5−23 × 10 7 M . Studying the spectra of HLX-1, that were taken in the low and hard state, we determine H α flux variability to be at least a factor 6, compared to observations taken during the high and soft state. This H α flux variability over one year indicates that the line originates close to the intermediate mass black hole, excluding the possibility that the line emanates from a surrounding nebula or a star cluster. The large variability associated with the X-ray states of HLX-1 confirms that the H α line is associated with the object and therefore validates the distance to HLX-1.

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On the formation of compact, massive subsystems in stellar clusters and its relation with intermediate-mass black holes

Cited by 46 publications

References 101 publications

The effect of stellar-mass black holes on the central kinematics of ω Cen: a cautionary tale for IMBH interpretations

The effect of stellar-mass black holes on the central kinematics of ω Cen: a cautionary tale for IMBH interpretations

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

Understanding the environment around the intermediate mass black hole candidate ESO 243-49 HLX-1

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