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Author | Title | Accn# | Year | Item Type | Claims |
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Sayak Datta |
Distinguishing black holes, neutron stars and exotic compact objects in inspiraling binaries |
D00109 |
2021 |
Book |
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| Title | Distinguishing black holes, neutron stars and exotic compact objects in inspiraling binaries : A thesis submitted for the degree of Doctor of Philosophy (in Physics) submitted to the Jawaharlal Nehru University, Delhi, India |
| Author(s) | Sayak Datta |
| Publication | Pune, IUCAA, 2021. |
| Description | 184 p. |
| Abstract Note | The primary defining feature of a classical black hole is being a perfect absorber.
Any evidence showing otherwise would imply a departure from the standard blackhole
picture. Energy and angular momentum absorption by the horizon of a black
hole is responsible for tidal heating in a binary. This effect is important in the late
stages of an extreme mass ratio inspiral around a spinning supermassive object,
which is one of the main targets of the upcoming LISA mission. We study the
potential of this effect to be used as a probe of the nature of supermassive objects.
We compute the orbital dephasing and the gravitational-wave signal emitted by a
point particle in circular, equatorial motion around a spinning supermassive object
to the leading order in the mass ratio. Absence of absorption by the central object
can affect the gravitational-wave signal dramatically, especially at high spin. This
effect will make it possible to put an unparalleled upper bound on the reflectivity
of exotic compact objects, at the level of O(0.01)%. This stringent bound would
exclude the possibility of observing echoes in the ringdown of a supermassive
binary merger. We also do Fisher analysis to estimate the errors that will be
present for EMRIs.
We study how tidal heating of an ECO gets modified due to the presence
of a reflective surface and what implication it brings for the gravitational wave
observations. We argue that the position of the reflective surface, ε ≳ 10−5, can
have an observational impact in extreme mass ratio inspirals. We also discuss a
possible degeneracy between ε and reflectivity, |R|2, in the context of parameter
estimation. In the context of comaparable mass binaries, we show how by careful monitoring
of the presence or absence of tidal deformability (TD) and tidal-heating
(TH) in the inspiral signal of compact object binaries in ground-based gravitational wave (GW) detectors one can test if its components are black holes or not.
The former property (TD) is finite for neutron stars but vanishes for black holes
(in General Relativity), whereas the latter is finite for black holes and negligible
for neutron stars, and affects the GW phase evolution of binaries in a distinctly
different way. We introduce waveform parameters that characterize the strength
of tidal-heating, and are zero when there is no horizon. We demonstrate how by
using those parameters Bayesian methods can distinguish the presence or absence
of horizons in a binary. This is a particularly exciting prospect owing to several
claims that these stellar-mass objects, especially, with masses heavier than those
of neutron stars, may not have a horizon but may be black hole mimickers or
exotic compact objects (ECOs). Perhaps more significant is the possibility that
our method can be used to test the presence or absence of horizons in mass-gap
binaries and, thereby, help detect the heaviest neutron star or the lightest black
hole. A proper accounting of tidal-heating in binary waveform models will also be
critical for an unbiased measurement of characteristics of the equation of state of
neutron stars in GW observations of binaries containing them – or even to probe
the existence of ECOs.
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| Notes | Jawaharlal Nehru University |
| ISBN,Price | Rs 0.00 |
| Classification | THESIS SECTION
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| Keyword(s) | 1. Black Hole - Thesis
2. GRAVITATIONAL WAVES - THESIS
3. IUCAA Thesis
4. Neutron star - Thesis
5. THESIS - IUCAA
6. THESIS - SAYAK DATTA
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| Item Type | Book |
Circulation Data
| Accession# | |
Call# | Status | Issued To | Return Due On | Physical Location |
| D00109 |
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