Hypervelocity stars from young stellar clusters in the Galactic Centre

Fragione, Giacomo; Capuzzo-Dolcetta, Roberto; Kroupa, Pavel

doi:10.1093/mnras/stx106

Cited by 31 publications

(21 citation statements)

References 66 publications

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“…Binary dynamics can lead to the formation of millisecond pulsars, comprised of rapidly rotating pulsars spun up by its companion. These sources are expected to be the main reason responsible for the Gamma-ray excess observed at the GC, although other possibilities have been invoked (Daylan et al 2016;Fermi-LAT Collaboration 2017), possibly related to the NSC formation history (Brandt & Kocsis 2015;Fragione et al 2017;Abbate et al 2018). Moreover, the possible detection of a pulsars population in the SMBH close vicinity can be crucial to probe general relativity in the strong field regime (Psaltis et al 2016).…”

Section: Introductionmentioning

confidence: 99%

DirectN-body simulation of the Galactic centre

Panamarev

Just

Spurzem

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We study the dynamics and evolution of the Milky Way nuclear star cluster performing a high resolution direct one-million-body simulation. Focusing on the interactions between such stellar system and the central supermassive black hole, we find that different stellar components adapt their overall distribution differently. After 5 Gyr, stellar mass black holes are characterized by a spatial distribution with power-slope −1.75, fully consistent with the prediction of Bahcall-Wolf pioneering work. Using the vast amount of data available, we infer the rate for tidal disruption events, being 4 × 10 −6 per yr, and estimate the number of objects that emit gravitational waves during the phases preceding the accretion onto the super-massive black hole, ∼ 270 per Gyr. We show that some of these sources could form extreme mass-ratio inspirals. We follow the evolution of binary stars population, showing that the initial binary fraction of 5% drops down to 2.5% inside the inner parsec. Also, we explored the possible formation of binary systems containing a compact object, discussing the implications for millisecond pulsars formation and the development of Ia Supernovae.

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Section: Introductionmentioning

confidence: 99%

DirectN-body simulation of the Galactic centre

Panamarev

Just

Spurzem

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…Stars may also be ejected from the Milky Way's Galactic Centre by stellar mass black hole kicks (Yu & Tremaine 2003;O'Leary & Loeb 2008) or IMBH inspirals (Yu & Tremaine 2003;Levin 2007). Cluster infall can also produce hypervelocity stars (Fragione et al 2017).…”

Section: Introductionmentioning

confidence: 99%

Constraints on the origins of hypervelocity stars: velocity distribution, mergers and star-formation history

Generozov,

Perets

2021

Preprint

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In recent years surveys have identified several dozen B stars in the Milky Way halo moving faster than the local escape speed. The origin of most of these hypervelocity stars (HVSs) is still poorly constrained. Here we show that the velocity distribution, and in particular the deficiency in >700 km s −1 HVSs is inconsistent with binary disruptions by the massive black hole (MBH) in the Galactic Centre. This conclusion holds in the full and empty loss cone regime, and for secular instabilities in eccentric disks. Accounting for multiple close encounters between binaries and the MBH, does not qualitatively change the results. Moreover, there is no observed counterpart population in the Galactic Centre that is consistent with the HVSs. The star-formation history could be tuned explain the HVS velocity distribution, but this tuning would produce a mismatch with the observed HVS flight times. Frequent stellar collisions of the binary components due to interactions with the MBH do not significantly impact the velocity distribution in the Galactic halo. Such collisions, however, can leave observable remnants in the Galactic Centre, and potentially explain the origins of G2-like dust clouds.

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“…However, HVBs may not be unique to SMBH binaries. Close encounters between hierarchical triples/quadruples and a single SMBH(e.g., Fragione et al 2017;Fragione 2018;Fragione & Gualandris 2018) can also disrupt the hierarchical multiples and in so doing eject HVBs.…”

Section: Introductionmentioning

confidence: 99%

Hypervelocity binaries from close encounters with a SMBH–IMBH binary: orbital properties and diagnostics

Wang

Leigh

Sesana

et al. 2018

Monthly Notices of the Royal Astronomical Society

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Hypervelocity binaries (HVBs) can be produced by a close encounter between stellar binaries and supermassive black hole (SMBH)-intermediate massive black hole (IMBH) binaries. We perform scattering experiments between tight stellar binaries and an SMBH-IMBH binary (within the observationally allowed parameters), using high-precision N-body integrations. Simulation results show that only a few HVBs can be produced in the Galactic center if it harbors a 4 × 10 3 M IMBH. However, we find that tight HVBs can be efficiently produced in prograde coplanar orbits with respect to the SMBH-IMBH binary. Therefore, the trajectories of the HVBs provide a promising way to constrain the IMBH orbital plane, if one exists. More importantly, we find that the ejected tight binaries are eccentric. For other galaxies hosting equal-mass SMBH binaries for which the HVB ejection rate is much higher relative to SMBH-IMBH binaries, these ejected compact binaries constitute promising extragalactic merger sources that could be detected by gravitational wave detectors.

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Hypervelocity stars from young stellar clusters in the Galactic Centre

Cited by 31 publications

References 66 publications

DirectN-body simulation of the Galactic centre

DirectN-body simulation of the Galactic centre

Constraints on the origins of hypervelocity stars: velocity distribution, mergers and star-formation history

Hypervelocity binaries from close encounters with a SMBH–IMBH binary: orbital properties and diagnostics

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