410 research outputs found
On the Likely Dynamical Origin of GW191109 and of Binary Black Hole Mergers with Negative Effective Spin
With the growing number of binary black hole (BBH) mergers detected by
LIGO/Virgo/KAGRA, several systems have become difficult to explain via isolated
binary evolution, having components in the pair-instability mass gap, high
orbital eccentricities, and/or spin-orbit misalignment. Here, we focus on
GW191109\_010717, a BBH merger with component masses of and
, and effective spin ,
which implies a spin-orbit misalignment of more than radians for at
least one of its components. Besides its component masses being in the
pair-instability mass gap, we show that isolated binary evolution is unlikely
to reproduce the spin-orbit misalignment of GW191109 with high confidence. On
the other hand, we demonstrate that BBHs dynamically assembled in dense star
clusters would naturally reproduce the spin-orbit misalignment and the masses
of GW191109, and the rates of GW191109-like events, if at least one of the
components were to be a second-generation BH. Finally, we generalize our
results to all the events with a measured negative effective spin, arguing that
GW200225 also has a likely dynamical origin.Comment: Submitted to ApJ, comments welcom
Direct Statistical Constraints on the Natal Kick velocity of a Black Hole in an X-ray Quiet Binary
In recent years, a handful of ``dark" binaries have been discovered with a
non-luminous compact object. Astrometry and radial velocity measurements of the
bright companion allow us to measure the post-supernova orbital elements of
such a binary. In this paper, we develop a statistical formalism to use such
measurements to infer the pre-supernova orbital elements, and the natal kick
imparted by the supernova (SN). We apply this formalism to the recent discovery
of an X-ray quiet binary with a black hole, VFTS 243, in the Large Magellanic
Cloud. Assuming an isotropic, Maxwellian distribution on natal kicks and using
broad agnostic mass priors, we find that kick velocity can be constrained to
km/s and the dispersion of the kick distribution to
km/s at 90 % confidence. We find that a Blaauw kick cannot be ruled out and
}that at least about was lost during the supernova with 90 %
confidence. The pre-SN orbital separation is found to be robustly constrained
to be around AU.Comment: 13 pages, 5 figure
What GW170729's exceptional mass and spin tells us about its family tree
No abstract available
Black Hole Genealogy: Identifying Hierarchical Mergers with Gravitational Waves
In dense stellar environments, the merger products of binary black hole mergers may undergo additional mergers. These hierarchical mergers are naturally expected to have higher masses than the first generation of black holes made from stars. The components of hierarchical mergers are expected to have significant characteristic spins, imprinted by the orbital angular momentum of the previous mergers. However, since the population properties of first-generation black holes are uncertain, it is difficult to know if any given merger is first-generation or hierarchical. We use observations of gravitational waves to reconstruct the binary black hole mass and spin spectrum of a population including the possibility of hierarchical mergers. We employ a phenomenological model that captures the properties of merging binary black holes from simulations of globular clusters. Inspired by recent work on the formation of low-spin black holes, we include a zero-spin subpopulation. We analyze binary black holes from LIGO and Virgo's first two observing runs, and find that this catalog is consistent with having no hierarchical mergers. We find that the most massive system in this catalog, GW170729, is mostly likely a first-generation merger, having a 4% probability of being a hierarchical merger assuming a 5 Ă 10â” M_â globular cluster mass. Using our model, we find that 99% of first-generation black holes in coalescing binaries have masses below 44 M_â, and the fraction of binaries with near-zero component spins is less than 0.16 (90% probability). Upcoming observations will determine if hierarchical mergers are a common source of gravitational waves
Evidence for hierarchical black hole mergers in the second LIGO--Virgo gravitational-wave catalog
We study the population properties of merging binary black holes in the
second LIGO--Virgo Gravitational-Wave Transient Catalog assuming they were all
formed dynamically in gravitationally bound clusters. Using a phenomenological
population model, we infer the mass and spin distribution of first-generation
black holes, while self-consistently accounting for hierarchical mergers.
Considering a range of cluster masses, we see compelling evidence for
hierarchical mergers in clusters with escape velocities . For our most probable cluster mass, we find that the
catalog contains at least one second-generation merger with credibility.
We find that the hierarchical model is preferred over an alternative model with
no hierarchical mergers (Bayes factor ) and that GW190521
is favored to contain two second-generation black holes with odds
, and GW190519, GW190602, GW190620, and GW190706 are
mixed-generation binaries with . However, our results depend
strongly on the cluster escape velocity, with more modest evidence for
hierarchical mergers when the escape velocity is . Assuming that all binary black holes are formed
dynamically in globular clusters with escape velocities on the order of tens of
, GW190519 and GW190521 are favored to include a
second-generation black hole with odds . In this case, we find
that of black holes from the inferred total population have masses that
are less than , and that this constraint is robust to our choice
of prior on the maximum black hole mass.Comment: 15 pages, 11 figures, 1 appendi
A Black Hole Kicked At Birth: MAXI J1305-704
When a compact object is formed in a binary, any mass lost during core
collapse will impart a kick on the binary's center of mass. Asymmetries in this
mass loss would impart an additional natal kick on the remnant black hole or
neutron star, whether it was formed in a binary or in isolation. While it is
well established that neutron stars receive natal kicks upon formation, it is
unclear whether black holes do as well. Here, we consider the low-mass X-ray
binary MAXI J1305-704, which has been reported to have a space velocity
200 km/s. In addition to integrating its trajectory to infer its
velocity upon formation of its black hole, we reconstruct its evolutionary
history, accounting for recent estimates of its period, black hole mass, mass
ratio, and donor effective temperature from photometric and spectroscopic
observations. We find that if MAXI J1305-704 formed via isolated binary
evolution in the thick Galactic disk, then its black hole received a natal kick
of at least 70 km/s with 95\% confidence.Comment: To be submitted; 9 pages, 5 figure
First measurement of the Hubble Constant from a Dark Standard Siren using the Dark Energy Survey Galaxies and the LIGO/Virgo BinaryâBlack-hole Merger GW170814
International audienceWe present a multi-messenger measurement of the Hubble constant H 0 using the binaryâblack-hole merger GW170814 as a standard siren, combined with a photometric redshift catalog from the Dark Energy Survey (DES). The luminosity distance is obtained from the gravitational wave signal detected by the Laser Interferometer Gravitational-Wave Observatory (LIGO)/Virgo Collaboration (LVC) on 2017 August 14, and the redshift information is provided by the DES Year 3 data. Black hole mergers such as GW170814 are expected to lack bright electromagnetic emission to uniquely identify their host galaxies and build an object-by-object Hubble diagram. However, they are suitable for a statistical measurement, provided that a galaxy catalog of adequate depth and redshift completion is available. Here we present the first Hubble parameter measurement using a black hole merger. Our analysis results in , which is consistent with both SN Ia and cosmic microwave background measurements of the Hubble constant. The quoted 68% credible region comprises 60% of the uniform prior range [20, 140] km sâ1 Mpcâ1, and it depends on the assumed prior range. If we take a broader prior of [10, 220] km sâ1 Mpcâ1, we find (57% of the prior range). Although a weak constraint on the Hubble constant from a single event is expected using the dark siren method, a multifold increase in the LVC event rate is anticipated in the coming years and combinations of many sirens will lead to improved constraints on H 0
Search for gravitational waves from Scorpius X-1 in the second Advanced LIGO observing run with an improved hidden Markov model
We present results from a semicoherent search for continuous gravitational waves from the low-mass x-ray binary Scorpius X-1, using a hidden Markov model (HMM) to track spin wandering. This search improves on previous HMM-based searches of LIGO data by using an improved frequency domain matched filter, the J-statistic, and by analyzing data from Advanced LIGO's second observing run. In the frequency range searched, from 60 to 650 Hz, we find no evidence of gravitational radiation. At 194.6 Hz, the most sensitive search frequency, we report an upper limit on gravitational wave strain (at 95% confidence) of h095%=3.47Ă10-25 when marginalizing over source inclination angle. This is the most sensitive search for Scorpius X-1, to date, that is specifically designed to be robust in the presence of spin wandering. © 2019 American Physical Society
Erratum: âSearches for Gravitational Waves from Known Pulsars at Two Harmonics in 2015â2017 LIGO Dataâ (2019, ApJ, 879, 10)
Due to an error at the publisher, in the published article the number of pulsars presented in the paper is incorrect in multiple places throughout the text. Specifically, "222" pulsars should be "221." Additionally, the number of pulsars for which we have EM observations that fully overlap with O1 and O2 changes from "168" to "167." Elsewhere, in the machine-readable table of Table 1 and in Table 2, the row corresponding to pulsar J0952-0607 should be excised as well. Finally, in the caption for Table 2 the number of pulsars changes from "188" to "187.
Search for gravitational waves from Scorpius X-1 in the second Advanced LIGO observing run with an improved hidden Markov model
We present results from a semicoherent search for continuous gravitational waves from the low-mass x-ray binary Scorpius X-1, using a hidden Markov model (HMM) to track spin wandering. This search improves on previous HMM-based searches of LIGO data by using an improved frequency domain matched filter, the J-statistic, and by analyzing data from Advanced LIGO's second observing run. In the frequency range searched, from 60 to 650 Hz, we find no evidence of gravitational radiation. At 194.6 Hz, the most sensitive search frequency, we report an upper limit on gravitational wave strain (at 95% confidence) of h095%=3.47Ă10-25 when marginalizing over source inclination angle. This is the most sensitive search for Scorpius X-1, to date, that is specifically designed to be robust in the presence of spin wandering. © 2019 American Physical Society
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