A. Samajdar
A5001801624- Pulsars and Gravitational Waves Research
- Geophysics and Gravity Measurements
- Radio Astronomy Observations and Technology
- Gamma-ray bursts and supernovae
- Cosmology and Gravitation Theories
- Astrophysical Phenomena and Observations
- Superconducting Materials and Applications
- High-pressure geophysics and materials
- Black Holes and Theoretical Physics
- Magnetic confinement fusion research
- Seismic Waves and Analysis
- Statistical and numerical algorithms
- Computational Physics and Python Applications
- Cold Atom Physics and Bose-Einstein Condensates
- Geophysics and Sensor Technology
- Advanced Frequency and Time Standards
- Dark Matter and Cosmic Phenomena
- Adaptive optics and wavefront sensing
- Model Reduction and Neural Networks
- Superconducting and THz Device Technology
- Scientific Research and Discoveries
- Relativity and Gravitational Theory
- Atomic and Subatomic Physics Research
- Astronomical Observations and Instrumentation
- Inertial Sensor and Navigation
University of Potsdam
2022-2025
Utrecht University
2020-2024
Istituto Nazionale di Fisica Nucleare, Sezione di Milano Bicocca
2022-2024
University of Milano-Bicocca
2021-2023
Université Paris Cité
2023
Centre National de la Recherche Scientifique
2023
Université Paris Sciences et Lettres
2023
Ollscoil na Gaillimhe – University of Galway
2023
Laboratoire Univers et Théories
2023
Laboratoire AstroParticule et Cosmologie
2023
We present the results of search for an isotropic stochastic gravitational wave background (GWB) at nanohertz frequencies using second data release European Pulsar Timing Array (EPTA) 25 millisecond pulsars and a combination with first Indian (InPTA). analysed (i) full 24.7-year EPTA set, (ii) its 10.3-year subset based on modern observing systems, (iii) set InPTA ten commonly timed pulsars, (iv) data. These combinations allowed us to probe contributions instrumental noise interstellar...
We present results from the search for a stochastic gravitational-wave background (GWB) as predicted by theory of General Relativity using six radio millisecond pulsars Data Release 2 (DR2) European Pulsar Timing Array (EPTA) covering timespan up to 24 years. A GWB manifests itself long-term low-frequency signal common all pulsars, red (CRS), with characteristic Hellings-Downs (HD) spatial correlation. Our analysis is performed two independent pipelines, \eprise{} and \tn{}+\ftwo{}, which...
We searched for an isotropic stochastic gravitational wave background in the second data release of International Pulsar Timing Array, a global collaboration synthesizing decadal-length pulsar-timing campaigns North America, Europe, and Australia. In our reference search power law strain spectrum form $h_c = A(f/1\,\mathrm{yr}^{-1})^{\alpha}$, we found strong evidence spectrally-similar low-frequency process amplitude $A 3.8^{+6.3}_{-2.5}\times10^{-15}$ spectral index $\alpha -0.5 \pm 0.5$,...
Abstract The Einstein Telescope (ET), the European project for a third-generation gravitational-wave detector, has reference configuration based on triangular shape consisting of three nested detectors with 10 km arms, where each detector 'xylophone' made an interferometer tuned toward high frequencies, and low frequencies working at cryogenic temperature. Here, we examine scientific perspectives under possible variations this design. We perform detailed evaluation science case single...
The combined observation of gravitational and electromagnetic waves from the coalescence two neutron stars marks beginning multi-messenger astronomy with (GWs). development accurate waveform models is a crucial prerequisite to extract information about properties binary system that generated detected GW signal. In star systems (BNS), tidal effects also need be incorporated in modeling for an representation. Building on previous work [Phys.Rev.D96 121501], we explore performance...
Pulsar timing arrays offer a probe of the low-frequency gravitational wave spectrum (1 - 100 nanohertz), which is intimately connected to number markers that can uniquely trace formation and evolution Universe. We present dataset results analysis from second data release European Timing Array (EPTA). The contains high-precision pulsar 25 millisecond pulsars collected with five largest radio telescopes in Europe, as well Large for Pulsars. forms foundation search waves by EPTA, presented...
Accurate and fast gravitational waveform (GW) models are essential to extract information about the properties of compact binary systems that generate GWs. Building on previous work, we present an extension NRTidal model for neutron star (BNS) waveforms. The upgrades (i) a new closed-form expression tidal contribution GW phase which includes further analytical knowledge is calibrated more accurate numerical relativity data than previously available; (ii) correction amplitude; (iii)...
The European Pulsar Timing Array (EPTA) and Indian (InPTA) collaborations have measured a low-frequency common signal in the combination of their second first data releases, respectively, with correlation properties gravitational wave background (GWB). Such may its origin number physical processes including cosmic population inspiralling supermassive black hole binaries (SMBHBs); inflation, phase transitions, strings, tensor mode generation by non-linear evolution scalar perturbations early...
The European Pulsar Timing Array (EPTA) and Indian (InPTA) collaborations have measured a low-frequency common signal in the combination of their second first data releases respectively, with correlation properties gravitational wave background (GWB). Such may its origin number physical processes including cosmic population inspiralling supermassive black hole binaries (SMBHBs); inflation, phase transitions, strings tensor mode generation by non-linear evolution scalar perturbations early...
Aims. The nanohertz gravitational wave background (GWB) is expected to be an aggregate signal of ensemble waves emitted predominantly by a large population coalescing supermassive black hole binaries in the centres merging galaxies. Pulsar timing arrays (PTAs), which are ensembles extremely stable pulsars at approximately kiloparsec distances precisely monitored for decades, most precise experiments capable detecting this background. However, subtle imprints that GWB induces on pulsar data...
Pulsar Timing Array experiments probe the presence of possible scalar or pseudoscalar ultralight dark matter particles through decade-long timing an ensemble galactic millisecond radio pulsars. With second data release European Array, we focus on most robust scenario, in which interacts only gravitationally with ordinary baryonic matter. Our results show that masses 10^{-24.0} eV≲m≲10^{-23.3} eV cannot constitute 100% measured local density, but can have at density ρ≲0.3 GeV/cm^{3}.
We present the results of a search for continuous gravitational wave signals (CGWs) in second data release (DR2) European Pulsar Timing Array (EPTA) Collaboration. The most significant candidate event from this has frequency 4–5 nHz. Such signal could be generated by supermassive black hole binary (SMBHB) local Universe. follow-up analysis using both Bayesian and frequentist methods. gives Bayes factor 4 favour presence CGW over common uncorrelated noise process. In contrast, estimates...
Gravitational waves emitted from the coalescence of neutron star binaries open a new window to probe matter and fundamental physics in unexplored, extreme regimes. To extract information about supranuclear inside stars properties compact binary systems, robust theoretical prescriptions are required. We give an overview general features dynamics gravitational wave signal during coalescence. briefly describe existing analytical numerical approaches investigate highly dynamical, strong-field...
We present the results of search for an isotropic stochastic gravitational wave background (GWB) at nanohertz frequencies using second data release European Pulsar Timing Array (EPTA) 25 millisecond pulsars and a combination with first Indian (InPTA). analysed (i) full 24.7-year EPTA set, (ii) its 10.3-year subset based on modern observing systems, (iii) set InPTA ten commonly timed pulsars, (iv) data. These combinations allowed us to probe contributions instrumental noise interstellar...
In the past few years, detection of gravitational waves from compact binary coalescences with Advanced LIGO and Virgo detectors has become routine. Future observatories will detect even larger numbers gravitational-wave signals, which also spend a longer time in detectors' sensitive band. This eventually lead to overlapping especially case Einstein Telescope (ET) Cosmic Explorer (CE). Using realistic distributions for merger rate as function redshift well component masses neutron star black...
Gravitational wave (GW) astronomy has consolidated its role as a new observational window to reveal the properties of compact binaries in Universe. In particular, discovery first binary neutron star coalescence, GW170817, led number scientific breakthroughs possibility place constraints on equation state cold matter at supranuclear densities. These and all results based them require accurate models describing GW signal extract source from measured signal. this article, we study potential...
ABSTRACT The European Pulsar Timing Array (EPTA) collaboration has recently released an extended data set for six pulsars (DR2) and reported evidence a common red noise signal. Here we present analysis each of the pulsars. We consider several types noise: (i) radio frequency independent, ‘achromatic’, time-correlated noise; (ii) variations dispersion measure scattering; (iii) system band (iv) deterministic signals (other than gravitational waves) that could be in PTA data. perform Bayesian...
We search for a stochastic gravitational wave background (SGWB) generated by network of cosmic strings using six millisecond pulsars from Data Release 2 (DR2) the European Pulsar Timing Array (EPTA). perform Bayesian analysis considering two models string loops, and compare it to simple power-law model which is expected population supermassive black hole binaries. Our main strong assumption that previously reported common red noise process SGWB. find one-parameter slightly favored over...
State-of-the-art searches for gravitational waves (GWs) in pulsar timing array (PTA) datasets model the signal as an isotropic, Gaussian, and stationary process described by a power law. In practice, none of these properties are expected to hold incoherent superposition GWs generated cosmic ensemble supermassive black hole binaries (SMBHBs). This stochastic is usually referred GW background (GWB) be primary PTA band. We performed systematic investigation performance current search...
Ultralight axionlike particles (ALPs) can be a viable solution to the dark matter problem. The scalar field associated with ALPs, coupled electromagnetic acts as an active birefringent medium, altering polarization properties of light through which it propagates. In particular, oscillations axionic induce monochromatic variations plane linearly polarized radiation astrophysical signals. radio emission millisecond pulsars provides excellent tool search for such manifestations, given their...
Over the last few years, there has been a large momentum to ensure that third-generation era of gravitational wave detectors will find its realisation in next decades, and numerous design studies have ongoing for some time. Some main factors determining cost Einstein Telescope lie length interferometer arms shape: L-shaped versus single triangular configuration. Both designs are further expected include xylophone configuration improvement on both ends frequency bandwidth detector. We...
According to the ``no-hair'' conjecture, a Kerr black hole (BH) is completely described by its mass and spin. In particular, spin-induced quadrupole moment of BH with $m$ dimensionless spin $\ensuremath{\chi}$ can be written as $Q=\ensuremath{-}\ensuremath{\kappa}{m}^{3}{\ensuremath{\chi}}^{2}$, where ${\ensuremath{\kappa}}_{\mathrm{BH}}=1$. Thus, measuring parameter $\ensuremath{\kappa}$, we test binary nature compact binaries distinguish them from composed other exotic objects, proposed in...
ABSTRACT In the coming years, third-generation detectors such as Einstein Telescope and Cosmic Explorer will enter network of ground-based gravitational-wave detectors. Their current design predicts a significantly improved sensitivity band with lower minimum frequency than existing This, combined increased arm length, leads to two major effects: detection more signals longer signals. Both result in large number overlapping It has been shown that can lead biases recovered parameters, which...
The inference of source parameters from gravitational-wave signals relies on theoretical models that describe the emitted waveform. Different model assumptions which computation these is based could lead to biases in analysis data. In this work, we sample directly four state-of-the-art binary black hole waveform different families, order investigate systematic 13 heaviest sources with moderate high signal-to-noise ratios third Gravitational-Wave Transient Catalog (GWTC-3). All include...
Extracting the properties of a binary system emitting gravitational waves relies on models describing last stages compact coalescence. In this article, we study potential biases inherent to current tidal waveform approximants for spinning and precessing systems. We perform Bayesian estimate intrinsic parameters highly neutron star Our analysis shows that one has include quadrupolar deformation stars due their rotation once dimensionless spins above $\ensuremath{\chi}\ensuremath{\sim}0.20$...