The Experts below are selected from a list of 10065 Experts worldwide ranked by ideXlab platform
A Gopakumar - One of the best experts on this subject based on the ideXlab platform.
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pulsar timing array signals induced by black hole binaries in relativistic Eccentric Orbits
Physical Review D, 2020Co-Authors: Abhimanyu Susobhanan, A Gopakumar, G Hobbs, Stephen TaylorAbstract:Individual supermassive black hole binaries in noncircular Orbits are possible nanohertz gravitational wave sources for the rapidly maturing Pulsar Timing Array experiments. We develop an accurate and efficient approach to compute Pulsar Timing Array signals due to gravitational waves from inspiraling supermassive black hole binaries in relativistic Eccentric Orbits. Our approach employs a Keplerian-type parametric solution to model third post-Newtonian accurate precessing Eccentric Orbits while a novel semianalytic prescription is provided to model the effects of quadrupolar order gravitational wave emission. These inputs lead to a semianalytic prescription to model such signals, induced by nonspinning black hole binaries inspiraling along arbitrary Eccentricity Orbits. Additionally, we provide a fully analytic prescription to model Pulsar Timing Array signals from black hole binaries inspiraling along moderately Eccentric Orbits, influenced by Boetzel et al. [Phys. Rev. D 96, 044011 (2017)]. These approaches are being incorporated into Enterprise and TEMPO2 for searching the presence of such binaries in Pulsar Timing Array datasets.
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gravitational wave amplitudes for compact binaries in Eccentric Orbits at the third post newtonian order tail contributions and postadiabatic corrections
Physical Review D, 2019Co-Authors: Y Boetzel, A Gopakumar, Guillaume Faye, C Mishra, B R IyerAbstract:We compute the tail contributions to the gravitational-wave mode amplitudes for compact binaries in Eccentric Orbits at the third post-Newtonian order of general relativity. We combine them with the already available instantaneous pieces and include the postadiabatic corrections required to fully account for the effects of radiation-reaction forces on the motion. We compare the resulting waveform in the small Eccentricity limit to the circular one, finding perfect agreement.
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ready to use fourier domain templates for compact binaries inspiraling along moderately Eccentric Orbits
Physical Review D, 2019Co-Authors: Srishti Tiwari, A Gopakumar, M Haney, Phurailatapam HemantakumarAbstract:We derive analytic expressions that provide the Fourier domain gravitational wave (GW) response function for compact binaries inspiraling along moderately Eccentric Orbits. These expressions include amplitude corrections to the two GW polarization states that are accurate to the first post-Newtonian (PN) order. Additionally, our fully third post-Newtonian (3PN)-accurate GW phase evolution incorporates Eccentricity effects up to sixth order at each PN order. Further, we develop a prescription to incorporate analytically the effects of the 3PN-accurate periastron advance in the GW phase evolution. This is how we provide a ready-to-use and efficient inspiral template family for compact binaries in moderately Eccentric Orbits. Preliminary GW data analysis explorations suggest that our template family should be required to construct analytic inspiral-merger-ringdown templates to model moderately Eccentric compact binary coalescence.
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frequency and time domain inspiral templates for comparable mass compact binaries in Eccentric Orbits
Physical Review D, 2016Co-Authors: Sashwat Tanay, M Haney, A GopakumarAbstract:Inspiraling compact binaries with non-negligible orbital Eccentricities are plausible gravitational wave (GW) sources for the upcoming network of GW observatories. In this paper, we present two prescriptions to compute post-Newtonian (PN) accurate inspiral templates for such binaries. First, we adapt and extend the postcircular scheme of Yunes et al. [Phys. Rev. D 80, 084001 (2009)] to obtain a Fourier-domain inspiral approximant that incorporates the effects of PN-accurate orbital Eccentricity evolution. This results in a fully analytic frequency-domain inspiral waveform with Newtonian amplitude and 2PN-order Fourier phase while incorporating Eccentricity effects up to sixth order at each PN order. The importance of incorporating Eccentricity evolution contributions to the Fourier phase in a PN-consistent manner is also demonstrated. Second, we present an accurate and efficient prescription to incorporate orbital Eccentricity into the quasicircular time-domain TaylorT4 approximant at 2PN order. New features include the use of rational functions in orbital Eccentricity to implement the 1.5PN-order tail contributions to the far-zone fluxes. This leads to closed form PN-accurate differential equations for evolving Eccentric Orbits, and the resulting time-domain approximant is accurate and efficient to handle initial orbital Eccentricities $\ensuremath{\le}0.9$. Preliminary GW data analysis implications are probed using match estimates.
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gravitational wave phasing for spinning compact binaries in inspiraling Eccentric Orbits
Physical Review D, 2011Co-Authors: A Gopakumar, Gerhard SchaferAbstract:We present a semi-analytic prescription to obtain gravitational wave (GW) phasing for spinning compact binaries in inspiraling Eccentric Orbits, while restricting the spin effects to the leading order spin-orbit coupling. We demonstrate that only the radial part of the orbital dynamics is amenable for a Keplerian-type solution that is compatible with the standard post-Newtonian (PN) accurate quasi-Keplerian parametrization for nonspinning compact binaries. We also derive PN-accurate equations governing the evolution of the Eulerian angles that are crucial to obtain temporally evolving GW polarization states and compute the associated fully 1PN accurate amplitude corrected GW polarization states. We show that it is not possible to obtain a Keplerian-type parametric solution for the angular part of the above dynamics in a noninertial frame that follows the precessing orbital plane [N. J. Cornish and J. S. Key, Phys. Rev. D 82, 044028 (2010)]. Further, we point out certain undesirable features present in their approach for doing GW phasing, like the use of precessing polarization vectors to construct the polarization states.
Robert J J Grand - One of the best experts on this subject based on the ideXlab platform.
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the origin of galactic metal rich stellar halo components with highly Eccentric Orbits
Monthly Notices of the Royal Astronomical Society, 2019Co-Authors: Azadeh Fattahi, V Belokurov, Alis J Deason, Carlos S Frenk, Facundo A Gomez, Robert J J Grand, Federico MarinacciAbstract:Using the astrometry from the ESA’s Gaia mission, previous works have shown that the Milky Way stellar halo is dominated by metal-rich stars on highly Eccentric Orbits. To shed light on the nature of this prominent halo component, we have analysed 28 Galaxy analogues in the Auriga suite of cosmological hydrodynamics zoom-in simulations. Some three quarters of the Auriga galaxies contain prominent components with high radial velocity anisotropy, β > 0.6. However, only in one third of the hosts do the high-β stars contribute significantly to the accreted stellar halo overall, similar to what is observed in the Milky Way. For this particular subset we reveal the origin of the dominant stellar halo component with high metallicity, [Fe/H]∼−1, and high orbital anisotropy, β > 0.8, by tracing their stars back to the epoch of accretion. It appears that, typically, these stars come from a single dwarf galaxy with a stellar mass of order of 109 − 1010 M⊙ that merged around 6 − 10 Gyr ago, causing a sharp increase in the halo mass. Our study therefore establishes a firm link between the excess of radially anisotropic stellar debris in the halo and an ancient head-on collision between the young Milky Way and a massive dwarf galaxy.
Federico Marinacci - One of the best experts on this subject based on the ideXlab platform.
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the origin of galactic metal rich stellar halo components with highly Eccentric Orbits
Monthly Notices of the Royal Astronomical Society, 2019Co-Authors: Azadeh Fattahi, V Belokurov, Alis J Deason, Carlos S Frenk, Facundo A Gomez, Robert J J Grand, Federico MarinacciAbstract:Using the astrometry from the ESA’s Gaia mission, previous works have shown that the Milky Way stellar halo is dominated by metal-rich stars on highly Eccentric Orbits. To shed light on the nature of this prominent halo component, we have analysed 28 Galaxy analogues in the Auriga suite of cosmological hydrodynamics zoom-in simulations. Some three quarters of the Auriga galaxies contain prominent components with high radial velocity anisotropy, β > 0.6. However, only in one third of the hosts do the high-β stars contribute significantly to the accreted stellar halo overall, similar to what is observed in the Milky Way. For this particular subset we reveal the origin of the dominant stellar halo component with high metallicity, [Fe/H]∼−1, and high orbital anisotropy, β > 0.8, by tracing their stars back to the epoch of accretion. It appears that, typically, these stars come from a single dwarf galaxy with a stellar mass of order of 109 − 1010 M⊙ that merged around 6 − 10 Gyr ago, causing a sharp increase in the halo mass. Our study therefore establishes a firm link between the excess of radially anisotropic stellar debris in the halo and an ancient head-on collision between the young Milky Way and a massive dwarf galaxy.
V Belokurov - One of the best experts on this subject based on the ideXlab platform.
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the origin of galactic metal rich stellar halo components with highly Eccentric Orbits
Monthly Notices of the Royal Astronomical Society, 2019Co-Authors: Azadeh Fattahi, V Belokurov, Alis J Deason, Carlos S Frenk, Facundo A Gomez, Robert J J Grand, Federico MarinacciAbstract:Using the astrometry from the ESA’s Gaia mission, previous works have shown that the Milky Way stellar halo is dominated by metal-rich stars on highly Eccentric Orbits. To shed light on the nature of this prominent halo component, we have analysed 28 Galaxy analogues in the Auriga suite of cosmological hydrodynamics zoom-in simulations. Some three quarters of the Auriga galaxies contain prominent components with high radial velocity anisotropy, β > 0.6. However, only in one third of the hosts do the high-β stars contribute significantly to the accreted stellar halo overall, similar to what is observed in the Milky Way. For this particular subset we reveal the origin of the dominant stellar halo component with high metallicity, [Fe/H]∼−1, and high orbital anisotropy, β > 0.8, by tracing their stars back to the epoch of accretion. It appears that, typically, these stars come from a single dwarf galaxy with a stellar mass of order of 109 − 1010 M⊙ that merged around 6 − 10 Gyr ago, causing a sharp increase in the halo mass. Our study therefore establishes a firm link between the excess of radially anisotropic stellar debris in the halo and an ancient head-on collision between the young Milky Way and a massive dwarf galaxy.
Gerhard Schafer - One of the best experts on this subject based on the ideXlab platform.
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gravitational wave phasing for spinning compact binaries in inspiraling Eccentric Orbits
Physical Review D, 2011Co-Authors: A Gopakumar, Gerhard SchaferAbstract:We present a semi-analytic prescription to obtain gravitational wave (GW) phasing for spinning compact binaries in inspiraling Eccentric Orbits, while restricting the spin effects to the leading order spin-orbit coupling. We demonstrate that only the radial part of the orbital dynamics is amenable for a Keplerian-type solution that is compatible with the standard post-Newtonian (PN) accurate quasi-Keplerian parametrization for nonspinning compact binaries. We also derive PN-accurate equations governing the evolution of the Eulerian angles that are crucial to obtain temporally evolving GW polarization states and compute the associated fully 1PN accurate amplitude corrected GW polarization states. We show that it is not possible to obtain a Keplerian-type parametric solution for the angular part of the above dynamics in a noninertial frame that follows the precessing orbital plane [N. J. Cornish and J. S. Key, Phys. Rev. D 82, 044028 (2010)]. Further, we point out certain undesirable features present in their approach for doing GW phasing, like the use of precessing polarization vectors to construct the polarization states.
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third post newtonian accurate generalized quasi keplerian parametrization for compact binaries in Eccentric Orbits
Physical Review D, 2004Co-Authors: Raoulmartin Memmesheimer, A Gopakumar, Gerhard SchaferAbstract:We present Keplerian-type parametrization for the solution of third post-Newtonian (3PN) accurate equations of motion for two nonspinning compact objects moving in an Eccentric orbit. The orbital elements of the parametrization are explicitly given in terms of the 3PN accurate conserved orbital energy and angular momentum in both Arnowitt-Deser-Misner--type and harmonic coordinates. Our representation will be required to construct post-Newtonian accurate ``ready to use'' search templates for the detection of gravitational waves from compact binaries in inspiralling Eccentric Orbits. Because of the presence of certain 3PN accurate gauge invariant orbital elements, the parametrization should be useful to analyze the compatibility of general relativistic numerical simulations involving compact binaries with the corresponding post-Newtonian descriptions. If required, the present parametrization will also be needed to compute post-Newtonian corrections to the currently employed ``timing formula'' for the radio observations of relativistic binary pulsars.