Details
| Original language | English |
|---|---|
| Pages (from-to) | 1768-1780 |
| Number of pages | 13 |
| Journal | Monthly Notices of the Royal Astronomical Society |
| Volume | 516 |
| Issue number | 2 |
| Early online date | 22 Aug 2022 |
| Publication status | Published - Oct 2022 |
Abstract
Timing a pulsar in a close orbit around the supermassive black hole SgrA∗ at the centre of the Milky Way would open the window for an accurate determination of the black hole parameters and for new tests of general relativity and alternative modified gravity theories. An important relativistic effect which has to be taken into account in the timing model is the propagation delay of the pulses in the gravitational field of the black hole. Due to the extreme mass ratio of the pulsar and the supermassive back hole we use the test particle limit to derive an exact analytical formula for the propagation delay of lightlike geodesics in a Kerr space-Time, and deduce a relativistic formula for the corresponding frame dragging effect on the arrival time. As an illustration, we treat an edge-on orbit in which the frame dragging effect on the emitted lightlike geodesics is expected to be maximal. We compare our formula for the propagation time delay with Post-Newtonian approaches, and in particular with the frame dragging terms derived in previous works by Wex & Kopeikin and Rafikov & Lai. Our approach correctly identifies the asymmetry of the frame dragging delay with respect to superior conjunction, avoids singularities in the time delay, and indicates that in the Post-Newtonian approach frame dragging effects on the lightlike pulses are generally slightly overestimated.
Keywords
- black hole physics, gravitation, pulsars: general, relativistic processes
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Astronomy and Astrophysics
- Earth and Planetary Sciences(all)
- Space and Planetary Science
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In: Monthly Notices of the Royal Astronomical Society, Vol. 516, No. 2, 10.2022, p. 1768-1780.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Propagation time delay and frame dragging effects of lightlike geodesics in the timing of a pulsar orbiting SgrA∗
AU - Ben-Salem, Bilel
AU - Hackmann, Eva
N1 - Publisher Copyright: © 2022 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.
PY - 2022/10
Y1 - 2022/10
N2 - Timing a pulsar in a close orbit around the supermassive black hole SgrA∗ at the centre of the Milky Way would open the window for an accurate determination of the black hole parameters and for new tests of general relativity and alternative modified gravity theories. An important relativistic effect which has to be taken into account in the timing model is the propagation delay of the pulses in the gravitational field of the black hole. Due to the extreme mass ratio of the pulsar and the supermassive back hole we use the test particle limit to derive an exact analytical formula for the propagation delay of lightlike geodesics in a Kerr space-Time, and deduce a relativistic formula for the corresponding frame dragging effect on the arrival time. As an illustration, we treat an edge-on orbit in which the frame dragging effect on the emitted lightlike geodesics is expected to be maximal. We compare our formula for the propagation time delay with Post-Newtonian approaches, and in particular with the frame dragging terms derived in previous works by Wex & Kopeikin and Rafikov & Lai. Our approach correctly identifies the asymmetry of the frame dragging delay with respect to superior conjunction, avoids singularities in the time delay, and indicates that in the Post-Newtonian approach frame dragging effects on the lightlike pulses are generally slightly overestimated.
AB - Timing a pulsar in a close orbit around the supermassive black hole SgrA∗ at the centre of the Milky Way would open the window for an accurate determination of the black hole parameters and for new tests of general relativity and alternative modified gravity theories. An important relativistic effect which has to be taken into account in the timing model is the propagation delay of the pulses in the gravitational field of the black hole. Due to the extreme mass ratio of the pulsar and the supermassive back hole we use the test particle limit to derive an exact analytical formula for the propagation delay of lightlike geodesics in a Kerr space-Time, and deduce a relativistic formula for the corresponding frame dragging effect on the arrival time. As an illustration, we treat an edge-on orbit in which the frame dragging effect on the emitted lightlike geodesics is expected to be maximal. We compare our formula for the propagation time delay with Post-Newtonian approaches, and in particular with the frame dragging terms derived in previous works by Wex & Kopeikin and Rafikov & Lai. Our approach correctly identifies the asymmetry of the frame dragging delay with respect to superior conjunction, avoids singularities in the time delay, and indicates that in the Post-Newtonian approach frame dragging effects on the lightlike pulses are generally slightly overestimated.
KW - black hole physics
KW - gravitation
KW - pulsars: general
KW - relativistic processes
UR - http://www.scopus.com/inward/record.url?scp=85142793155&partnerID=8YFLogxK
U2 - 10.48550/arXiv.2203.10931
DO - 10.48550/arXiv.2203.10931
M3 - Article
AN - SCOPUS:85142793155
VL - 516
SP - 1768
EP - 1780
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
IS - 2
ER -