Pulsar Timing Arrays (PTAs) use an ensemble of highly stable millisecond pulsars to detect the nanohertz stochastic gravitational wave background (GWB), expected to arise primarily from a population of inspiralling supermassive black hole binaries. In addition to the detection of this stochastic background, PTAs can probe a wide range of astrophysical phenomena, including tests of gravity. I ...
Parameter estimation and population inference for binary black holes from gravitational-wave data are limited by observational uncertainties. In particular, spin parameters—crucial for understanding the formation channels of binary black holes—remain more weakly constrained than other parameters, making it difficult to draw conclusive conclusions.
The large uncertainty in spin estimation...
The LIGO–Virgo–KAGRA collaboration has reported several detections of massive binary black holes with total masses exceeding 100 M⊙. In addition to their large masses, some of these systems exhibit evidence of high component spins. On the other hand, owing to the short duration of their signals, these events could alternatively be explained by other transient sources. In this study, we propose...
Over 300 gravitational wave (GW) events have been detected by the LIGO-Virgo-KAGRA (LVK) collaboration. Most of them originate from binary black hole(BBH) coalescences, and a few are from binary neutron stars (BNS). Unlike BBH signals, GWs from BNS are long signals lasting up to a few minutes in the detector band, which makes parameter estimation computationally expensive. Even with current...
I'll present methods to optimize the analysis of long-duration gravitational waves (GWs) from compact binary coalescences (CBCs) and search for sub-solar mass CBCs in LIGO data using the methods. The LIGO–Virgo–KAGRA (LVK) collaboration, operating the world’s most sensitive GW observatories, searches for CBC signals in the 0.2–1.0 solar mass range, providing leading constraints on the...
In this study, we focus on the high frequency gravitational-wave emission from the hyper-massive neutron star temporarily formed after a binary neutron star (BNS) merger. We evaluate how accurately KAGRA can estimate the post-merger peak frequency $f_{\mathrm{peak}}$ using the BayesWave analysis on numerical-relativity waveform models injected into Gaussian noise colored by the detector’s PSD....
We present results of a joint search with the Dark Energy Camera (DECam) and Prime Focus Spectrograph (PFS) for the optical counterpart of the LIGO-Virgo-KAGRA event S250328ae, a binary black hole merger candidate of high significance detected at a distance of 511+-82 Mpc and localized within an area of 3 (15) square degrees at 50% (90%) confidence. We observed the 90% confidence area with...
We consider a pure Yang-Mills theory with $\mathrm{Spin}(4N) (N\geq2)$ gauge group.
In this framework, color flux tubes are stable against breaking due to the absence of dynamical matter in the fundamental representation.
If confinement occurs after inflation, the phase transition produces color flux tubes with typical separations set by the Hubble scale, allowing them to extend to...
Strongly lensed gravitational waves offer a new way to study dark matter structure on subgalactic scales. In the wave-optics regime, gravitational waves propagating through a population of dark matter subhalos acquire frequency-dependent amplitude and phase distortions that encode the small-scale matter distribution along the line of sight.
We compute the full diffraction integral for...
Density spikes are steep enhancements in the dark matter (DM) distribution that arise from gravitational infall onto a central compact object. In the standard scenario where DM consists of particles, such spikes may form around a sub-dominant population of massive primordial black holes (PBHs), potentially leading to large enhancements of the DM density in their vicinity.
The situation can...
Since the joint detection of gravitational waves from GW 170817 and electromagnetic radiation from a short gamma-ray burst, GRB 170817A, the multimessenger community has worked extensively to investigate these events. This detection showed that binary neutron star mergers are progenitors of short GRBs and demonstrated the advantages of multimessenger observations. Although GRB 170817A was...
Astrophysical neutrinos are expected to be produced during transient phenomena that also produce gravitational waves, such as compact binary coalescences, in particular those involving neutron stars, or core-collapse supernovae. Gravitational waves are routinely detected by the LIGO-Virgo-KAGRA interferometers, while the ANTARES and KM3NeT deep-sea neutrino telescopes are sensitive to neutrino...
