Supersymmetric Higgs-portal and X-ray lines

X-ray Lines From Gamma-ray Bursts

X-ray lines have been recently detected in the afterglows of a few gamma-ray bursts. We derive constraints on the physical conditions in the line-emitting gas, using as an example the multiple Kα lines detected by Reeves et al. (2002) in GRB 011211. We argue that models previously discussed in the literature require either a very extreme geometry or too much mass in the line-emitting region. We...

Photospheres, Comptonization and X-ray Lines in Gamma Ray Bursts

Steep X-ray spectral slopes, X-ray excesses and preferred spectral energy breaks in the 01-0.3 MeV range are discussed as the possible consequences of the photospheric component of the GRB relativistic outflow, and of pair breakdown in internal shocks leading to comptonization on semirelativistic electrons or MHD waves. We also discuss the X-ray and UV spectra of GRB afterglows occuring in a de...

X-ray lines, progenitor and beaming of Gamma-Ray Bursts

X-ray emission features have been detected in at least five GRB afterglows. Their detection and properties are of great importance in our understanding of the nature of the GRB progenitor. Moreover, they provide us with an uncollimated source of photons, allowing us to put firm constraints on the total energy produced in GRBs, and therefore on their degree of collimation. I will review the radi...

Exploring the Higgs portal

The PG X-ray QSO sample: Links between the UV-X-ray Continuum and Emission Lines

The UV to soft X-rays of luminous AGNs dominate their bolometric luminosity, driven by an accretion-powered dynamo at the center. These photons ionize the surrounding gas, thereby providing clues to fueling and exhaust. Two sets of important relationships – neither of them understood – link the continuum and gas properties. (i) Boroson & Green’s ‘eigenvector 1’ relationships: Steeper soft X-ray...