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Jackson, C. B., Servant, G., Shaughnessy, G., Tait, T. M. P., & Taoso, M. (2010). Higgs in space! J. Cosmol. Astropart. Phys., 04(4), 004–29pp.
Abstract: We consider the possibility that the Higgs can be produced in dark matter annihilations, appearing as a line in the spectrum of gamma rays at an energy determined by the masses of the WIMP and the Higgs itself. We argue that this phenomenon occurs generally in models in which the the dark sector has large couplings to the most massive states of the SM and provide a simple example inspired by the Randall-Sundrum vision of dark matter, whose 4d dual corresponds to electroweak symmetry-breaking by strong dynamics which respect global symmetries that guarantee a stable WIMP. The dark matter is a Dirac fermion that couples to a Z' acting as a portal to the Standard Model through its strong coupling to top quarks. Annihilation into light standard model degrees of freedom is suppressed and generates a feeble continuum spectrum of gamma rays. Loops of top quarks mediate annihilation into gamma Z, gamma h, and gamma Z', providing a forest of lines in the spectrum. Such models can be probed by the Fermi/GLAST satellite and ground-based Air Cherenkov telescopes.
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Herrero-Garcia, J., Schwetz, T., & Zupan, J. (2012). On the annual modulation signal in dark matter direct detection. J. Cosmol. Astropart. Phys., 03(3), 005–28pp.
Abstract: We derive constraints on the annual modulation signal in Dark Matter (DM) direct detection experiments in terms of the unmodulated event rate. A general bound independent of the details of the DM distribution follows from the assumption that the motion of the earth around the sun is the only source of time variation. The bound is valid for a very general class of particle physics models and also holds in the presence of an unknown unmodulated background. More stringent bounds are obtained, if modest assumptions on symmetry properties of the DM halo are adopted. We illustrate the bounds by applying them to the annual modulation signals reported by the DAMA and CoGeNT experiments in the framework of spin-independent elastic scattering. While the DAMA signal satisfies our bounds, severe restrictions on the DM mass can be set for CoGeNT.
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Guerrero, M., Mora-Perez, G., Olmo, G. J., Orazi, E., & Rubiera-Garcia, D. (2021). Charged BTZ-type solutions in Eddington-inspired Born-Infeld gravity. J. Cosmol. Astropart. Phys., 11(11), 025–23pp.
Abstract: We construct an axially symmetric solution of Eddington-inspired Born-Infeld gravity coupled to an electromagnetic field in 2 + 1 dimensions including a (negative) cosmological constant term. This is achieved by using a recently developed mapping procedure that allows to generate solutions in certain families of metric-affine gravity theories starting from a known seed solution of General Relativity, which in the present case corresponds to the electrically charged Banados-Teitelboim-Zanelli (BTZ) solution. We discuss the main features of the new configurations, including the modifications to the ergospheres and horizons, the emergence of wormhole structures, and the consequences for the regularity (or not) of these space-times via geodesic completeness.
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Guerrero, M., Mora-Perez, G., Olmo, G. J., Orazi, E., & Rubiera-Garcia, D. (2020). Rotating black holes in Eddington-inspired Born-Infeld gravity: an exact solution. J. Cosmol. Astropart. Phys., 07(7), 058–31pp.
Abstract: We find an exact, rotating charged black hole solution within Eddington-inspired Born-Infeld gravity. To this end we employ a recently developed correspondence or mapping between modified gravity models built as scalars out of contractions of the metric with the Ricci tensor, and formulated in metric-affine spaces (Ricci-Based Gravity theories) and General Relativity. This way, starting from the Kerr-Newman solution, we show that this mapping bring us the axisymmetric solutions of Eddington-inspired Born-Infeld gravity coupled to a certain model of non-linear electrodynamics. We discuss the most relevant physical features of the solutions obtained this way, both in the spherically symmetric limit and in the fully rotating regime. Moreover, we further elaborate on the potential impact of this important technical progress for bringing closer the predictions of modified gravity with the astrophysical observations of compact objects and gravitational wave astronomy.
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Guerrero, M., Olmo, G. J., & Rubiera-Garcia, D. (2021). Double shadows of reflection-asymmetric wormholes supported by positive energy thin-shells. J. Cosmol. Astropart. Phys., 04(4), 066–26pp.
Abstract: We consider reflection-asymmetric thin-shell wormholes within Palatini f(R) gravity using a matching procedure of two patches of electrovacuum space-times at a hypersurface (the shell) via suitable junction conditions. The conditions for having (linearly) stable wormholes supported by positive-energy matter sources are determined. We also identify some subsets of parameters able to locate the shell radius above the event horizon (when present) but below the photon sphere (on both sides). We illustrate with an specific example that such two photon spheres allow an observer on one of the sides of the wormhole to see another (circular) shadow in addition to the one generated by its own photon sphere, which is due to the photons passing above the maximum of the effective potential on its side and bouncing back across the throat due to a higher effective potential on the other side. We finally comment on the capability of these double shadows to seek for traces of new gravitational physics beyond that described by General Relativity.
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