Search Publications
A cosmic UV/X-ray background model update
Faucher-Giguère, Claude-André
We present an updated model of the cosmic ionizing background from the UV to the X-rays. Relative to our previous model, the new model provides a better match to a large number of up-to-date empirical constraints, including: (1) new galaxy and AGN luminosity functions; (2) stellar spectra including binary stars; (3) obscured and unobscured AGN; (4…
The first six months of the Advanced LIGO's and Advanced Virgo's third observing run with GRANDMA
Bertin, E.; Kann, D. A.; Berthier, J. +74 more
We present the Global Rapid Advanced Network Devoted to the Multi-messenger Addicts (GRANDMA). The network consists of 21 telescopes with both photometric and spectroscopic facilities. They are connected together thanks to a dedicated infrastructure. The network aims at coordinating the observations of large sky position estimates of transient eve…
Short gamma-ray bursts within 200 Mpc
Troja, E.; Sakamoto, T.; Lien, A. Y. +5 more
We present a systematic search for short-duration gamma-ray bursts (GRBs) in the local Universe based on 14 yr of observations with the Neil Gehrels Swift Observatory. We cross-correlate the GRB positions with the GLADE catalogue of nearby galaxies, and find no event at a distance ≲100 Mpc and four plausible candidates in the range 100 Mpc ≲ D ≲ 2…
Hard X-ray selected giant radio galaxies - II. Morphological evidence of restarted radio activity
Venturi, T.; Dallacasa, D.; Ubertini, P. +10 more
About 6 per cent of radio galaxies (RGs) can reach linear sizes larger than 0.7 Mpc, and are then classified as giant radio galaxies (GRGs). The conditions that make possible the formation of such big structures are still not clear - either core accretion properties or environmental factors. Recent studies have shown that GRGs can be up to four ti…
Search for 7Be in the outbursts of four recent novae
Bonifacio, P.; Hernanz, M.; Molaro, P. +3 more
Following the recent detection of 7Be II in the outburst spectra of classical novae, we report the search for this isotope in the outbursts of four recent bright novae by means of high-resolution Ultraviolet and Visual Echelle Spectrograph (UVES) observations. The 7Be II λλ313.0583, 313.1228 nm doublet resonance lines are det…
Spectral characterization of the non-thermal X-ray emission of gamma-ray pulsars
Coti Zelati, Francesco; Torres, Diego F.; Li, Jian +1 more
We report on a detailed spectral characterization of the non-thermal X-ray emission for a large sample of gamma-ray pulsars in the second Fermi Large Area Telescope catalogue. We outline the criteria adopted for the selection of our sample, its completeness, and critically describe different approaches to estimate the spectral shape and flux of pu…
Detection of ultra-high-energy gamma rays from the Crab Nebula: physical implications
Aharonian, Felix; Khangulyan, Dmitry; Arakawa, Masanori
The Crab Nebula is an extreme particle accelerator that boosts the energy of electrons up to a few PeV (10^{15} eV), close to the maximum energy allowed theoretically. The physical conditions in the acceleration site and the nature of the acceleration process itself remain highly uncertain. The key information about the highest-energy accelerated …
On the nature of the soft γ-ray emission in the hard state of the black hole transient GRS 1716-249
Motta, S. E.; Segreto, A.; Casella, P. +9 more
The black hole transient GRS 1716-249 was monitored from the radio to the γ-ray band during its 2016-2017 outburst. This paper focuses on the spectral energy distribution (SED) obtained in 2017 February-March, when GRS 1716-249 was in a bright hard spectral state. The soft γ-ray data collected with the INTEGRAL/SPI telescope show the presence of a…
Time evolution of cyclotron line of Her X-1: a detailed statistical analysis including new AstroSat data
Staubert, R.; Maitra, C.; Bhattacharya, D. +1 more
The cyclotron line feature in the X-ray spectrum of the accretion-powered pulsar Her X-1 has been observed and monitored for over three decades. The line energy exhibited a slow secular decline over the period 1995-2014, with a possible (not confirmed) indication of a reversal thereafter. Recent works have shown that the temporal evolution of the …
Hard-X-ray-selected active galactic nuclei - I. A radio view at high frequencies
McHardy, I.; Behar, E.; Tombesi, F. +5 more
A thorough study of radio emission in active galactic nuclei (AGNs) is of fundamental importance to understand the physical mechanisms responsible for the emission and the interplay between accretion and ejection processes. High-frequency radio observations can target the nuclear contribution of smaller emitting regions and are less affected by ab…