19 research outputs found
Spatial and Binary Parameter Distributions of Black Hole Binaries in the Milky Way Detectable with Gaia
Soon after the Gaia data release (DR) 3 in June 2022, some candidates (and
one confirmed) of detached black hole (BH) - luminous companion (LC) binaries
have been reported. Existing and future detections of astrometric BH-LC
binaries will shed light on the spatial distribution of these systems, which
can deepen our understanding of the natal kicks and the underlying formation
mechanism of BHs. By tracking Galactic orbits of BH-LC binaries obtained from
BSE, we find that distributions of BH mass and the height from the Galactic
plane |z| would help us give a constraint on supernova model. We also indicate
that the correlations of (i) orbital periods and eccentricities, and (ii) BH
mass and could be clues for the strength of natal kick, and that the
correlations of (, ) may tell us a clue for common envelope (CE)
efficiency. We also discuss the possibility of forming BH-LC binaries like the
BH binary candidates reported in Gaia DR3 and Gaia BH 1, finding that if the
candidates as well as the confirmed binary originate from isolated binaries,
they favor models which produce low-mass BHs and have high CE efficiencies
exceeding unity.Comment: 25 pages, 17 figures. Accepted by Ap
Compact Binary Formation in Open Star Clulsters I: High Formation Efficiency of Gaia BHs and Their Multiplicities
Gaia BHs, black hole (BH) binaries discovered from database of an astrometric
telescope Gaia, pose a question to the standard binary evolution model. We have
assessed if Gaia BHs can be formed through dynamical capture in open clusters
rather than through isolated binary evolution. We have performed gravitational
-body simulations of open clusters with in total for
each metallicity , , and . We have discovered one Gaia
BH-like binary escaping from an open cluster, and found that the formation
efficiency of Gaia BHs in open clusters () is larger
than in isolated binaries () by 3 orders of
magnitude. The Gaia BH-like binary is the inner binary of a triple star system.
Gaia BHs can have tertiary stars frequently, if they are formed in open
clusters. We have estimated the number of Gaia BHs in the Milky Way disk to
, large enough for the number of Gaia BHs discovered so far.
Our results indicate that the discoveries of Gaia BHs do not request the
reconstruction of the standard binary evolution model, and that Gaia BHs are a
probe for the dynamics of open clusters already evaporated.Comment: 7 pages, 6 figures, 1 table, submitted to MNRA
Search for a Black Hole Binary in Gaia DR3 Astrometric Binary Stars with Spectroscopic Data
We report the discovery of a candidate binary system consisting of a black
hole (BH) and a red giant branch star from the Gaia DR3. This binary system is
discovered from 64096 binary solutions for which both astrometric and
spectroscopic data are available. For this system, the astrometric and
spectroscopic solutions are consistent with each other, making this system a
confident candidate of a BH binary. The primary (visible) star in this system,
Gaia DR3 5870569352746779008, is a red giant branch whose mass is quite
uncertain. Fortunately, albeit the uncertainty of the primary's mass, the
secondary (dark) object in this system has a mass of with a
probability of %, based on the orbital parameters. The mass of the
secondary object is much larger than the maximum neutron star mass (
), which indicates that the secondary object is likely a BH. We argue
that, if this dark object is not a BH, this system must be a more exotic
system, in which the primary red giant branch star orbits around a triple star
system (or a higher-order multiple star system) whose total mass is more than
. Future deep photometric observations are awaited to rule out
such an exotic possibility and to determine whether or not this system is a
genuine BH binary. If this is a genuine BH binary, this has the longest period
( days) among discovered so far.Comment: 13 pages, 6 figure, 2 tables. Comments welcom
An Early-warning System for Electromagnetic Follow-up of Gravitational-wave Events
Binary neutron stars (BNSs) will spend ≃10–15 minutes in the band of Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo detectors at design sensitivity. Matched-filtering of gravitational-wave (GW) data could in principle accumulate enough signal-to-noise ratio (S/N) to identify a forthcoming event tens of seconds before the companions collide and merge. Here we report on the design and testing of an early-warning GW detection pipeline. Early-warning alerts can be produced for sources that are at low enough redshift so that a large enough S/N accumulates ~10–60 s before merger. We find that about 7% (49%) of the total detectable BNS mergers will be detected 60 s (10 s) before the merger. About 2% of the total detectable BNS mergers will be detected before merger and localized to within 100 deg² (90% credible interval). Coordinated observing by several wide-field telescopes could capture the event seconds before or after the merger. LIGO–Virgo detectors at design sensitivity could facilitate observing at least one event at the onset of merger