A5054708320- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Geophysics and Gravity Measurements
- High-pressure geophysics and materials
- Cosmology and Gravitation Theories
- Particle physics theoretical and experimental studies
- Geophysics and Sensor Technology
- Particle Detector Development and Performance
- Statistical and numerical algorithms
- Quantum Chromodynamics and Particle Interactions
- Atomic and Subatomic Physics Research
- High-Energy Particle Collisions Research
- Astrophysics and Cosmic Phenomena
- Geomagnetism and Paleomagnetism Studies
- Particle Accelerators and Free-Electron Lasers
- Magnetic confinement fusion research
- Superconducting Materials and Applications
- Seismology and Earthquake Studies
- Astro and Planetary Science
- Seismic Waves and Analysis
- Seismic Imaging and Inversion Techniques
- Inertial Sensor and Navigation
- Digital Innovation in Industries
- Astronomical Observations and Instrumentation
Max Planck Institute for Gravitational Physics
2013-2024
Leibniz University Hannover
2017-2024
Montclair State University
2021
University of Wisconsin–Milwaukee
2021
Max Planck Society
2020
University of Trento
2015-2017
Istituto Nazionale di Fisica Nucleare, Trento Institute for Fundamental Physics And Applications
2016-2017
Scuola Internazionale Superiore di Studi Avanzati
2010-2011
Istituto Nazionale di Fisica Nucleare
2011
University of Tübingen
2008-2010
First measurements of the Collins and Sivers asymmetries charged hadrons produced in deep-inelastic scattering muons on a transversely polarized 6-LiD target are presented. The data were taken 2002 with COMPASS spectrometer using muon beam CERN SPS at 160 GeV/c. asymmetry turns out to be compatible zero, as does measured within present statistical errors.
We present numerical simulations of binary neutron star mergers, comparing irrotational binaries to NSs rotating aligned the orbital angular momentum. For first time, we study spinning BNSs employing nuclear physics equations state, namely ones Lattimer and Swesty as well Shen, Horowitz, Teige. mainly equal mass systems leading a hypermassive (HMNS), analyze in detail its structure dynamics. In order exclude gauge artifacts, introduce novel coordinate system used for post-processing. The...
Merging binary neutron stars (BNSs) represent the ultimate targets for multimessenger astronomy, being among most promising sources of gravitational waves (GWs), and, at same time, likely accompanied by a variety electromagnetic counterparts across entire spectrum, possibly including short gamma-ray bursts (SGRBs) and kilonova/macronova transients. Numerical relativity simulations play central role in study these events. In particular, given importance magnetic fields, various aspects this...
We describe in detail the implementation of a simplified approach to radiative transfer general relativity by means well-known neutrino leakage scheme (NLS). In particular, we carry out an extensive investigation properties and limitations NLS for isolated relativistic stars level that has not been discussed before general-relativistic context. Although numerous tests considered here are rather idealized, they provide well-controlled environment which understand relationship between matter...
The recent multimessenger observation of the short gamma-ray burst (SGRB) GRB 170817A together with gravitational wave (GW) event GW170817 provides evidence for long-standing hypothesis associating SGRBs binary neutron star (BNS) mergers. nature remnant object powering SGRB, which could have been either an accreting black hole (BH) or a long-lived magnetized (NS), is, however, still uncertain. General relativistic magnetohydrodynamic (GRMHD) simulations merger process represent powerful tool...
The merger of two neutron stars will in general lead to the formation a torus surrounding black hole whose rotational energy can be tapped potentially power short gamma-ray burst. We have studied equal-mass binaries with spins aligned orbital angular momentum determine maximum spin reach. Our initial data consists irrotational which we add various amounts rotation increase total momentum. Although violates constraint equations, use constraint-damping CCZ4 formulation yields evolutions...
In this work, we study the merger of two neutron stars with a gravitational mass $1.4\text{ }\text{ }{M}_{\ensuremath{\bigodot}}$ each, employing Shen-Horowitz-Teige equation state. This state is corner case, allowing formation stable star given total baryonic $3.03\text{ }{M}_{\ensuremath{\bigodot}}$. We investigate in unprecedented detail structure remnant, particular distribution, thermal structure, and rotation profile. also compute fluid trajectories both inside remnant those relevant...
We present fully GRMHD simulations of the merger binary neutron star (BNS) systems. consider BNSs producing a hypermassive (HMNS) that collapses to spinning black hole (BH) surrounded by magnetized accretion disk in few tens ms. investigate whether such systems may launch relativistic jets and power short gamma-ray bursts. study effects different equations state (EOSs), mass ratios, magnetic field orientations. For all cases, we detailed investigation matter dynamics evolution, with...
Magnetic fields are expected to play a key role in the dynamics and ejection mechanisms that accompany merger of two neutron stars. General relativistic magnetohydrodynamic (MHD) simulations offer unique opportunity unravel details ongoing physical processes. Nevertheless, current numerical studies severely limited by fact any affordable resolution remains insufficient fully capture small-scale dynamo, initially triggered Kelvin-Helmholtz instability, later sourced several MHD processes...
We present a determination of the gluon polarization Delta G/G in nucleon, based on helicity asymmetry quasi-real photoproduction events, Q^2<1(GeV/c)^2, with pair large transverse-momentum hadrons final state. The data were obtained by COMPASS experiment at CERN using 160 GeV polarized muon beam scattered 6-LiD target. for selected events is = 0.002 +- 0.019(stat.) 0.003(syst.). From this value, we obtain leading-order QCD analysis G/G=0.024 0.089(stat.) 0.057(syst.) x_g 0.095 and mu^2...
We study the $f$-mode frequencies and damping times of nonrotating neutron stars (NS) in general relativity (GR) by solving linearized perturbation equations, with aim to establish "universal" relations that depend only weakly on equations state (EOS). Using a more comprehensive set EOSs, we re-examine some proposed linearizations describe parameters terms mass radius star (NS), test recent proposal for expressing as quadratic functions effective compactness. Our extensive results each...
Following previous work in vacuum spacetimes, we investigate the constraint-damping properties presence of matter recently developed traceless, conformal and covariant Z4 (CCZ4) formulation Einstein equations. First, evolve an isolated neutron star with ideal gas equation state subject to a constraint-violating perturbation. We compare evolution constraints using CCZ4 Baumgarte-Shibata-Shapiro-Nakamura-Oohara-Kojima (BSSNOK) systems. Second, study collapse unstable spherical black hole....
We present general relativistic numerical simulations of binary neutron star (BNS) mergers with different initial spin configurations. focus on models stars mass $1.4\text{ }\text{ }{M}_{\ensuremath{\bigodot}}$ each, which employ the equation state (EOS) by Shen, Horowitz, and Teige, result in stable NSs as merger remnants. For comparison, we consider two irrotational equal ($M=1.35\text{ }{M}_{\ensuremath{\bigodot}}$) unequal ($M=1.29$, $1.42\text{ BNS using APR4 EOS, a supramassive...
We present new results of fully general relativistic magnetohydrodynamic simulations binary neutron star (BNS) mergers performed with the Whisky code. All models use a piecewise polytropic approximation APR4 equation state for cold matter, together 'hybrid' part to incorporate thermal effects during evolution. consider both equal and unequal-mass models, total masses such that either supramassive NS or black hole is formed after merger. Each model evolved without magnetic field initially...
We present fully general relativistic simulations of binary neutron star mergers, employing a new zero- temperature chiral effective field theory equation state, the BL EOS. offer comparison with respect to older GM3 EOS, which is based on standard mean theory, and separately determine impact mass. provide detailed analysis dynamics, focus post-merger phase. For all models, we extract gravitational wave strain frequency spectrum. Further, amount, velocity, polar distribution ejected matter,...
Modern simulation codes for general relativistic ideal magnetohydrodynamics are all facing a long standing technical problem given by the need to recover fundamental variables from those that evolved in time. In case, this requires numerical solution of system nonlinear equations. Although several approaches available, none has proven completely reliable. A recent study comparing different methods showed can fail, particular important case strong magnetization and moderate Lorentz factors....
After the detection of gravitational waves caused by coalescence compact objects in mass range neutron stars, GW170817, several studies have searched for an imprint tidal effects signal, employing different model assumptions. One important distinction is whether or not to assume that both are stars and obey same equation state. Some assumed independent properties. Others a universal state, addition deformability follows certain phenomenological relations. An question gravitational-wave data...
In this article, we present a numerical scheme for relativistic ideal hydrodynamics on arbitrary curved spacetimes in up to three spatial dimensions. The aim of is an improved treatment stationary or quasistationary scenarios without loss general applicability. This achieved by treating pressure and gravitational forces, which are usually computed with unrelated methods, within unified framework. We derive special formulation the source terms hydrodynamic evolution equations, then utilized...
We investigate strong nonlinear damping effects which occur during high amplitude oscillations of neutron stars, and the gravitational waves they produce. For this, we use a general relativistic hydrodynamics code in conjunction with fixed spacetime (Cowling approximation) polytropic equation state (EOS). Gravitational are estimated using quadrupole formula. Our main interest l=m=2 f modes subject to CFS (Chandrasekhar, Friedman, Schutz) instability, but also axisymmetric quasiradial modes....
Weak reactions are critical for the neutron richness of matter dynamically ejected after merger two stars. The richness, defined by electron fraction (), determines which heavy elements produced r-process and thus directly impacts kilonova light curve. In this work, we have performed a systematic detailed post-processing study impact weak on distribution entropy dynamic ejecta obtained from an equal mass star binary simulated in full general relativity with microscopic equation state....
The discovery of the coalescence binary neutron star GW170817 was a watershed moment in field gravitational wave astronomy. Among rich variety information that we were able to uncover from this first non-electromagnetic measurement radius, and cold nuclear equation state. It also led large state model-selection study gravitational-wave data. In those studies Bayesian nested sampling runs conducted for each candidate model compute their evidence Such studies, though invaluable, are...
In this article, we investigate inertial modes of rigidly rotating neutron stars, i.e. for which the Coriolis force is dominant. This done using assumption a fixed spacetime (Cowling approximation). We present frequencies and eigenfunctions sequence stars with polytropic equation state, covering broad range rotation rates. The were obtained nonlinear general relativistic hydrodynamic evolution code. further show that eigenequations oscillation can be written in particularly simple form case...
A fully pipelined and massively parallel data acquisition system has been developed for the COMPASS experiment at CERN. The main requirements are to read 250000 detector channels a trigger rate of up 100 kHz. Such high rates only possible when using hit selection mechanism on front-end combined with dead-time free readout. For this purpose, time-to-digital converter (TDC) chip is used all time measurement applications in COMPASS. Distributed, field programmable gate array (FPGA)-based...