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Importance of being nonminimally coupled: Scalar Hawking radiation from regular black holes
Marco Calzà, Massimiliano Rinaldi, Sunny Vagnozzi
In curved space-time, a scalar field is generically expected to couple to curvature, via a coupling of the form . Yet in the study of Hawking emission from regular black…
Imprints of screened dark energy on nonlocal quantum correlations
Fabiano Feleppa, Gaetano Lambiase, Sunny Vagnozzi
We investigate how screening mechanisms, reconciling light scalar fields driving cosmic acceleration with local fifth force constraints, can be probed via their impact on non-local…
Primordial regular black holes as all the dark matter. III. Covariant canonical quantum gravity models
Marco Calzà, Davide Pedrotti, Guan-Wen Yuan +1
In earlier companion papers, we showed that non-singular primordial black holes (PBHs) could account for all the dark matter (DM) over a significantly wider mass range compared to…
Primordial regular black holes as all the dark matter. II. Non-time-radial-symmetric and loop quantum gravity-inspired metrics
Marco Calzà, Davide Pedrotti, Sunny Vagnozzi
It is a common belief that a theory of quantum gravity should ultimately cure curvature singularities which are inevitable within General Relativity, and plague for instance the Sc…
Primordial regular black holes as all the dark matter. I. Time-radial-symmetric metrics
Marco Calzà, Davide Pedrotti, Sunny Vagnozzi
Primordial black holes (PBHs) are usually assumed to be described by the Schwarzschild or Kerr metrics, which however feature unwelcome singularities. We study the possibility that…
Implications of cosmologically coupled black holes for pulsar timing arrays
Marco Calzà, Francesco Gianesello, Massimiliano Rinaldi +1
It has been argued that realistic models of (singularity-free) black holes (BHs) embedded within an expanding Universe are coupled to the large-scale cosmological dynamics, with st…
Event Horizon Telescope observations exclude compact objects in baseline mimetic gravity
Mohsen Khodadi, Sunny Vagnozzi, Javad T. Firouzjaee
Mimetic gravity has gained significant appeal in cosmological contexts, but static spherically symmetric space-times within the baseline theory are highly non-trivial: the two natu…
Quasinormal modes-shadow correspondence for rotating regular black holes
Davide Pedrotti, Sunny Vagnozzi
Eikonal quasinormal modes (QNMs) of black holes (BHs) and parameters of null geodesics, ultimately tied to the appearance of BHs to external observers, are known to be related, and…
Tests of Loop Quantum Gravity from the Event Horizon Telescope Results of Sgr A
Misba Afrin, Sunny Vagnozzi, Sushant G. Ghosh
The Event Horizon Telescope (EHT) collaboration's image of the compact object at the galactic center is the first direct evidence of the supermassive black hole (BH) Sgr A. The…
Horizon-scale tests of gravity theories and fundamental physics from the Event Horizon Telescope image of Sagittarius A
Sunny Vagnozzi, Rittick Roy, Yu-Dai Tsai +12
Horizon-scale images of black holes (BHs) and their shadows have opened an unprecedented window onto tests of gravity and fundamental physics in the strong-field regime. We conside…
Black holes with scalar hair in light of the Event Horizon Telescope
Mohsen Khodadi, Alireza Allahyari, Sunny Vagnozzi +1
Searching for violations of the no-hair theorem (NHT) is a powerful way to test gravity, and more generally fundamental physics, particularly with regards to the existence of addit…
Concerns regarding the use of black hole shadows as standard rulers
Sunny Vagnozzi, Cosimo Bambi, Luca Visinelli
Recently, Tsupko et al. have put forward the very interesting proposal to use the shadows of high-redshift supermassive black holes (SMBHs) as standard rulers. This would in princi…
Magnetically charged black holes from non-linear electrodynamics and the Event Horizon Telescope
Alireza Allahyari, Mohsen Khodadi, Sunny Vagnozzi +1
Non-linear electrodynamics (NLED) theories are well-motivated extensions of QED in the strong field regime, and have long been studied in the search for regular black hole (BH) sol…
Do we have any hope of detecting scattering between dark energy and baryons through cosmology?
Sunny Vagnozzi, Luca Visinelli, Olga Mena +1
We consider the possibility that dark energy and baryons might scatter off each other. The type of interaction we consider leads to a pure momentum exchange, and does not affect th…
Hunting for extra dimensions in the shadow of M87*
Sunny Vagnozzi, Luca Visinelli
The Event Horizon Telescope has recently provided the first image of the dark shadow around the supermassive black hole M87*. The observation of a highly circular shadow provides s…
Testing the rotational nature of the supermassive object M87* from the circularity and size of its first image
Cosimo Bambi, Katherine Freese, Sunny Vagnozzi +1
The Event Horizon Telescope (EHT) collaboration has recently released the first image of a black hole (BH), opening a new window onto tests of general relativity in the strong fiel…
Alive and well: mimetic gravity and a higher-order extension in light of GW170817
Alessandro Casalino, Massimiliano Rinaldi, Lorenzo Sebastiani +1
The near-simultaneous multi-messenger detection of the gravitational wave (GW) event GW170817 and its optical counterpart, the short -ray burst GRB170817A, implies that deviatio…
Mimicking dark matter and dark energy in a mimetic model compatible with GW170817
Alessandro Casalino, Massimiliano Rinaldi, Lorenzo Sebastiani +1
The recent observation of the the gravitational wave event GW170817 and of its electromagnetic counterpart GRB170817A, from a binary neutron star merger, has established that the s…
Cosmological dynamics of mimetic gravity
Jibitesh Dutta, Wompherdeiki Khyllep, Emmanuel N. Saridakis +2
We present a detailed investigation of the dynamical behavior of mimetic gravity with a general potential for the mimetic scalar field. Performing a phase-space and stability analy…
Brane-world extra dimensions in light of GW170817
Luca Visinelli, Nadia Bolis, Sunny Vagnozzi
The search for extra dimensions is a challenging endeavor to probe physics beyond the Standard Model. The joint detection of gravitational waves (GW) and electromagnetic (EM) signa…
Recovering a MOND-like acceleration law in mimetic gravity
Sunny Vagnozzi
We reconsider the recently proposed mimetic gravity, focusing in particular on whether the theory is able to reproduce the inferred flat rotation curves of galaxies. We extend the…
Mimetic gravity: a review of recent developments and applications to cosmology and astrophysics
L. Sebastiani, S. Vagnozzi, R. Myrzakulov
Mimetic gravity is a Weyl-symmetric extension of General Relativity, related to the latter by a singular disformal transformation, wherein the appearance of a dust-like perfect flu…
Covariant Horava-like and mimetic Horndeski gravity: cosmological solutions and perturbations
Guido Cognola, Ratbay Myrzakulov, Lorenzo Sebastiani +2
We consider a variant of the Nojiri-Odintsov covariant Horava-like gravitational model, where diffeomorphism invariance is broken dynamically via a non-standard coupling to a perfe…
Static spherically symmetric solutions in mimetic gravity: rotation curves & wormholes
Ratbay Myrzakulov, Lorenzo Sebastiani, Sunny Vagnozzi +1
In this work, we analyse static spherically symmetric solutions in the framework of mimetic gravity, an extension of general relativity where the conformal degree of freedom of gra…