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Measuring kinematic anisotropies with pulsar timing arrays
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Ameek Malhotra ,
Gianmassimo Tasinato ,
Ivonne Zavala Carrasco
Physical Review D, Volume: 110, Issue: 6
Swansea University Authors:
Ameek Malhotra , Gianmassimo Tasinato , Ivonne Zavala Carrasco
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DOI (Published version): 10.1103/physrevd.110.063526
Abstract
Recent pulsar timing array (PTA) collaborations show strong evidence for a stochastic gravitational wave background (SGWB) with the characteristic Hellings-Downs interpulsar correlations. The signal may stem from supermassive black hole binary mergers, or early Universe phenomena. The former is expe...
| Published in: | Physical Review D |
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| ISSN: | 2470-0010 2470-0029 |
| Published: |
American Physical Society (APS)
2024
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| Online Access: |
Check full text
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| URI: | https://cronfa.swan.ac.uk/Record/cronfa67446 |
| Abstract: |
Recent pulsar timing array (PTA) collaborations show strong evidence for a stochastic gravitational wave background (SGWB) with the characteristic Hellings-Downs interpulsar correlations. The signal may stem from supermassive black hole binary mergers, or early Universe phenomena. The former is expected to be strongly anisotropic, while primordial backgrounds are likely to be predominantly isotropic with small fluctuations. In the case the observed SGWB is of cosmological origin, our relative motion with respect to the SGWB rest frame is a guaranteed source of anisotropy, leading to (10−3) energy density fluctuations of the SGWB. For such cosmological SGWB, kinematic anisotropies are likely to be larger than the intrinsic anisotropies, akin to the cosmic microwave background (CMB) dipole anisotropy. We assess the sensitivity of current PTA data to the kinematic dipole anisotropy, and we also forecast at what extent the magnitude and direction of the kinematic dipole can be measured in the future with an SKA-like experiment. We also discuss how the spectral shape of the SGWB and the location of the pulsars to monitor affect the prospects of detecting the kinematic dipole with PTA. In the future, a detection of this anisotropy may even help resolve the discrepancy in the magnitude of the kinematic dipole as measured by CMB and large-scale structure observations. |
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| Keywords: |
General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO) |
| College: |
Faculty of Science and Engineering |
| Funders: |
Swansea University |
| Issue: |
6 |