3 research outputs found
Search for Post-merger Gravitational Waves from the Remnant of the Binary Neutron Star Merger GW170817
The first observation of a binary neutron star coalescence by the Advanced
LIGO and Advanced Virgo gravitational-wave detectors offers an unprecedented
opportunity to study matter under the most extreme conditions. After such a
merger, a compact remnant is left over whose nature depends primarily on the
masses of the inspiralling objects and on the equation of state of nuclear
matter. This could be either a black hole or a neutron star (NS), with the
latter being either long-lived or too massive for stability implying delayed
collapse to a black hole. Here, we present a search for gravitational waves
from the remnant of the binary neutron star merger GW170817 using data from
Advanced LIGO and Advanced Virgo. We search for short ( s) and
intermediate-duration ( s) signals, which includes
gravitational-wave emission from a hypermassive NS or supramassive NS,
respectively. We find no signal from the post-merger remnant. Our derived
strain upper limits are more than an order of magnitude larger than those
predicted by most models. For short signals, our best upper limit on the
root-sum-square of the gravitational-wave strain emitted from 1--4 kHz is
Hz at 50% detection
efficiency. For intermediate-duration signals, our best upper limit at 50%
detection efficiency is Hz for
a millisecond magnetar model, and
Hz for a bar-mode model. These results indicate that post-merger
emission from a similar event may be detectable when advanced detectors reach
design sensitivity or with next-generation detectors
On the progenitor of binary neutron star merger GW170817
On 2017 August 17 the merger of two compact objects with masses consistent with two neutron stars was discovered through gravitational-wave (GW170817), gamma-ray (GRB 170817A), and optical (SSS17a/AT 2017gfo) observations. The optical source was associated with the early-type galaxy NGC 4993 at a distance of just ~40 Mpc, consistent with the gravitational-wave measurement, and the merger was localized to be at a projected distance of ~2 kpc away from the galaxy's center. We use this minimal set of facts and the mass posteriors of the two neutron stars to derive the first constraints on the progenitor of GW170817 at the time of the second supernova (SN). We generate simulated progenitor populations and follow the three-dimensional kinematic evolution from binary neutron star (BNS) birth to the merger time, accounting for pre-SN galactic motion, for considerably different input distributions of the progenitor mass, pre-SN semimajor axis, and SN-kick velocity. Though not considerably tight, we find these constraints to be comparable to those for Galactic BNS progenitors. The derived constraints are very strongly influenced by the requirement of keeping the binary bound after the second SN and having the merger occur relatively close to the center of the galaxy. These constraints are insensitive to the galaxy's star formation history, provided the stellar populations are older than 1 Gyr.B. P. Abbott … Miftar Ganija … Won Kim … Jesper Munch … David J Ottaway … Peter J Veitch … et al. (LIGO Scientific Collaboration and Virgo Collaboration
First low-frequency Einstein@Home all-sky search for continuous gravitational waves in Advanced LIGO data
We report results of a deep all-sky search for periodic gravitational waves from isolated neutron stars in data from the first Advanced LIGO observing run. This search investigates the low frequency range of Advanced LIGO data, between 20 and 100 Hz, much of which was not explored in initial LIGO. The search was made possible by the computing power provided by the volunteers of the Einstein@Home project. We find no significant signal candidate and set the most stringent upper limits to date on the amplitude of gravitational wave signals from the target population, corresponding to a sensitivity depth of 48.7 [1/Hz]. At the frequency of best strain sensitivity, near 100 Hz, we set 90% confidence upper limits of 1.8×10-25. At the low end of our frequency range, 20 Hz, we achieve upper limits of 3.9×10-24. At 55 Hz we can exclude sources with ellipticities greater than 10-5 within 100 pc of Earth with fiducial value of the principal moment of inertia of 1038 kg m2