Tidal disruption near black holes 
and their mimickers

Banerjee, Pritam; Paul, Suvankar; Shaikh, Rajibul; Sarkar, Tapobrata

doi:10.1088/1475-7516/2021/03/042

Cited by 7 publications

(2 citation statements)

References 64 publications

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“…The recent observation of Sgr A * by the EHT finds that the observed image is consistent with the expected appearance of a Kerr black hole [1]. However, various non-vacuum solutions in GR as well as those in various modified gravity theories deviate from the Kerr (or Schwarzschild) solution and might potentially mimic many of the properties of the Kerr (or Schwarzschild) black hole [12][13][14][15][16][17][18][19][20][21][22]. Hence, in this EHT era, it becomes important to study images and shadows of these objects and compare them with the EHT results.…”

Section: Introductionmentioning

confidence: 85%

Testing black hole mimickers with the Event Horizon Telescope image of Sagittarius A$^*$

Shaikh¹

2022

Preprint

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The Event Horizon Telescope (EHT) has recently observed the image and shadow of the supermassive compact object Sagittarius A * (Sgr A * ). According to the EHT collaboration, the observed image is consistent with the expected appearance of a Kerr black hole. However, it is well-known that some non-Kerr objects may mimic many of the properties of the Kerr black hole, and hence, their shadows might be consistent with the observed shadow of Sgr A * . In this work, we consider two black hole mimickers and study their shadows. The first mimicker is a rotating generalisation of the recently proposed static, spherically symmetric black-bounce spacetime by Simpson and Visser where the central Schwarzschild singularity is replaced by a minimal surface. The second one is the γ-metric which is a static, axially symmetric singular solution of the vacuum Einstein's equations without an event horizon. We put constraint on the parameters of these black hole mimickers by comparing their shadows with the one observed for Sgr A * .

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Section: Introductionmentioning

confidence: 85%

Testing black hole mimickers with the Event Horizon Telescope image of Sagittarius A$^*$

Shaikh¹

2022

Preprint

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“…One of the oldest as well as interesting ECOs correspond to the wormholes, which are spacetimes joining two distinct universes by a throat [37][38][39][40][41][42]. If one can travel from one universe to the other, it will be refereed to as a traversable wormhole and this, in general, requires exotic matter fields.…”

Section: Introductionmentioning

confidence: 99%

Gravitational wave memory in wormhole spacetimes

Chakraborty,

Bhattacharya,

Chakraborty

2022

Preprint

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Gravitational wave memory is studied in the context of a certain class of braneworld wormholes. Unlike other wormhole geometries, this novel class of wormholes do not require any exotic matter fields for its traversability. First, we study geodesics in this wormhole spacetime, in the presence of a gravitational wave pulse. The resulting evolution of the geodesic separation shows the presence of displacement and velocity memory effects. Motivated by the same, we study the memory effects at null infinity using the Bondi-Sachs formalism, adapted for braneworld wormhole. Our analysis provides a non-trivial change of the Bondi mass after the passage of a burst of gravitational radiation and hence manifests the memory effect at null infinity. In both of these exercises, the presence of extra dimension and the wormhole nature of the spacetime geometry gets imprinted in the memory effect. Since future gravitational wave detectors will be able to probe the memory effect, the present work provides another avenue to search for compact objects other than black holes.

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Testing black hole mimickers with the Event Horizon Telescope image of Sagittarius A*

Shaikh

2023

Monthly Notices of the Royal Astronomical Society

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The Event Horizon Telescope (EHT) has recently observed the image and shadow of the supermassive compact object Sagittarius A* (Sgr A*). According to the EHT collaboration, the observed image is consistent with the expected appearance of a Kerr black hole. However, it is well-known that some non-Kerr objects may mimic many of the properties of the Kerr black hole, and hence, their shadows might be consistent with the observed shadow of Sgr A*. In this work, we consider two black hole mimickers and study their shadows. The first mimicker is a rotating generalisation of the recently proposed static, spherically symmetric black-bounce spacetime by Simpson and Visser where the central Schwarzschild singularity is replaced by a minimal surface. The second one is the γ-metric which is a static, axially symmetric singular solution of the vacuum Einstein’s equations without an event horizon. We put constraint on the parameters of these black hole mimickers by comparing their shadows with the observed shadow of Sgr A*.

show abstract

Tidal disruption near black holes and their mimickers

Cited by 7 publications

References 64 publications

Testing black hole mimickers with the Event Horizon Telescope image of Sagittarius A$^*$

Testing black hole mimickers with the Event Horizon Telescope image of Sagittarius A$^*$

Gravitational wave memory in wormhole spacetimes

Testing black hole mimickers with the Event Horizon Telescope image of Sagittarius A*

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