A toy model for a baby universe inside a black hole

Chakrabarty, Hrishikesh; Abdujabbarov, Ahmadjon; Malafarina, Daniele; Bambi, Cosimo

doi:10.1140/epjc/s10052-020-7964-0

Cited by 31 publications

(33 citation statements)

References 41 publications

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“…Cosmological theories such as holographic big bang (Pourhasan, Afshordi, & Mann 2014; Altamirano et al 2017) can also be related to a cosmological-scale axis. The existence of such axis is also aligned with the black hole cosmology theory (Pathria 1972; Easson & Brandenberger 2001; Chakrabarty et al 2020), providing an explanation to cosmic inflation that does not involve dark energy. The spin of black holes is originated from the spin of the stars from which they were created (McClintock et al 2006).…”

Section: Discussionmentioning

confidence: 62%

Large-scale asymmetry in galaxy spin directions: evidence from the Southern hemisphere

Shamir

2021

Publ. Astron. Soc. Aust.

122

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Recent observations using several different telescopes and sky surveys showed patterns of asymmetry in the distribution of galaxies by their spin directions as observed from Earth. These studies were done with data imaged from the Northern hemisphere, showing excellent agreement between different telescopes and different analysis methods. Here, data from the DESI Legacy Survey was used. The initial dataset contains $\sim\!2.2\times 10^7$ galaxy images, reduced to $\sim\!8.1\times 10^5$ galaxies annotated by their spin direction using a symmetric algorithm. That makes it not just the first analysis of its kind in which the majority of the galaxies are in the Southern hemisphere, but also by far the largest dataset used for this purpose to date. The results show strong agreement between opposite parts of the sky, such that the asymmetry in one part of the sky is similar to the inverse asymmetry in the corresponding part of the sky in the opposite hemisphere. Fitting the distribution of galaxy spin directions to cosine dependence shows a dipole axis with probability of 4.66 $\sigma$ . Interestingly, the location of the most likely axis is within close proximity to the CMB Cold Spot. The profile of the distribution is nearly identical to the asymmetry profile of the distribution identified in Pan-STARRS, and it is within 1 $\sigma$ difference from the distribution profile in SDSS and HST. All four telescopes show similar large-scale profile of asymmetry.

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Section: Discussionmentioning

confidence: 62%

Large-scale asymmetry in galaxy spin directions: evidence from the Southern hemisphere

Shamir

2021

Publ. Astron. Soc. Aust.

122

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“…was first extensively explored in [47][48][49] (see also [50][51][52][53] for some other works, and [54] for a popular science book on these ideas). In [55,56], the idea that a "limiting curvature construction" might lead to singularity resolution was explored.…”

Section: Jhep05(2021)090mentioning

confidence: 99%

Non-singular black holes with a zero-shear S-brane

Brandenberger

Heisenberg

Robnik

2021

J. High Energ. Phys.

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We propose a construction with which to resolve the black hole singularity and enable an anisotropic cosmology to emerge from the inside of the hole. The model relies on the addition of an S-brane to the effective action which describes the geometry of space-time. This space-like defect is located inside of the horizon on a surface where the Weyl curvature reaches a limiting value. We study how metric fluctuations evolve from the outside of the black hole to the beginning of the cosmological phase to the future of the S-brane. Our setup addresses i) the black hole singularity problem, ii) the cosmological singularity problem and iii) the information loss paradox since the outgoing Hawking radiation is entangled with the state inside the black hole which becomes the new universe.

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“…Furthermore, a straightforward integration of the first equation in (6) leads to the following cumulative mass distribution…”

Section: The Einasto Density Profilementioning

confidence: 99%

“…To examine the nature of Black Holes (BH) [1] more closely, it would be desirable to infer more about their interior structure, be it from the geometric point of view [2][3][4][5][6][7] or probing into the question what kind of matter has contributed to its formation [8][9][10]. In view of the fact that baryonic and leptonic matter constitutes only four percent of the content of the universe and secondly recalling that the density profiles of the major component, Dark Matter (DM), grows as we approach the galactic center [11][12][13], the question whether the central a e-mail: davide.batic@ku.ac.ae (corresponding author) b e-mail: 100045070@ku.ac.ae c e-mail: mnowakos@uniandes.edu.co galactic BH has a close connection to DM is a well-posed problem.…”

Section: Introductionmentioning

confidence: 99%

Fuzzy dark matter black holes and droplets

2021

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We consider the possibility of having Dark Matter (DM) black holes motivated by the Einasto density profile. This generalizes both the noncommutative mini black hole model and allows DM to enter as the matter constituent which makes up the black hole. We show that it is possible to construct a black hole solution for each value of the Einasto index and for different values of the mass parameter, provided that the we work with the energy–momentum tensor of an anisotropic fluid. In particular, we achieve that by first considering the equation of state (EOS) $$p_r=-\rho $$ p r = - ρ . It turns out that the corresponding black hole solution exhibits a horizon structure similar to that of a Reissner–Nordström black hole and the central singularity is replaced by a regular de Sitter core. We also show that if the previous EOS is replaced by a nonlocal one, it is possible to construct a self-gravitating fuzzy DM droplet but also in this case, the radial pressure is negative. Finally, we contemplate scenarios of different dark matter black holes with moderate mass values which could have formed in galaxies. In particular, we probe the possibility whether such black holes could also be the central galactic objects.

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A toy model for a baby universe inside a black hole

Cited by 31 publications

References 41 publications

Large-scale asymmetry in galaxy spin directions: evidence from the Southern hemisphere

Large-scale asymmetry in galaxy spin directions: evidence from the Southern hemisphere

Non-singular black holes with a zero-shear S-brane

Fuzzy dark matter black holes and droplets

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