8 papers
A unified modeling of X-ray and gamma-ray spectro-polarimetric data: the case of Cygnus X-1
Tristan Bouchet, Thomas Siegert, Victoria Grinberg +4
Recent X-ray and soft gamma-ray spectro-polarimetric observations of black hole X-ray binaries, such as Cygnus X-1, reveal discrepancies that challenge current models of accretion…
Cosmological - Pair-Production Background
Mika A. Gelowicz, Thomas Siegert, Saurabh Mittal +10
The paper calculates how photons from the cosmic photon background interact with each other to produce electron‑positron pairs across cosmic time, and evaluates the resulting secon…
Stellar flares cannot explain the Galactic 511 keV emission
Saurabh Mittal, Thomas Siegert, Francesca Calore +12
The authors assess whether stellar flares can produce enough positrons to explain the Milky Way’s 511 keV annihilation line and conclude that flares fall short by several orders of…
-Ray Lines -- Signatures of Nucleosynthesis, Cosmic Rays, Positron Annihilation, and Fundamental Physics
Thomas Siegert, Francesca Calore, Pierre Jean +6
The nuclear -ray lines in the MeV range of the electromagnetic spectrum hold a vast variety of astrophysical, particle-physical, and fundamental physical information that is ot…
Production of radioactive Na in core-collapse supernovae: the Ne-E(L) component in presolar grains and its possible consequences on supernova observations
M. Pignatari, S. Amari, P. Hoppe +8
Presolar graphite grains carry the isotopic signatures of their parent stars. A significant fraction of presolar graphites shows isotopic abundance anomalies relative to solar for…
Imaging the positron annihilation line with 20 years of INTEGRAL/SPI observations
Hiroki Yoneda, Thomas Siegert, Saurabh Mittal
The e e annihilation line at 511 keV provides a unique probe for studying the distribution and origin of positrons in our Galaxy. The SPI spectrometer on INTEGRAL has obser…