Search Publications
Cosmic rays cannot explain the high ionisation rates in the Galactic centre
Gabici, S.; Recchia, S.; Ravikularaman, S. +1 more
Context. The H2 ionisation rate in the central molecular zone, located in the Galactic centre, is estimated to be ζ ∼ 2 × 10‑14 s‑1, based on observations of H3+ lines. This value is two to three orders of magnitude larger than that measured anywhere else in the Galaxy. Aims. Due to the high d…
Tracing the Milky Way spiral arms with 26Al: The role of nova systems in the 2D distribution of 26Al
Della Valle, M.; Matteucci, F.; Spitoni, E. +2 more
Context. Massive stars are one of the most important and investigated astrophysical production sites of 26Al, a short-lived radioisotope with an ~1 Myr half-life. Its short lifetime prevents us from observing its complete chemical history, and only the 26Al that was recently produced by massive stars can be observed. Hence, i…
Multi-wavelength study of 1eRASS J085039.9‑421151 with eROSITA, NuSTAR, and X-shooter
Santangelo, A.; Heber, U.; Dauser, T. +23 more
The eROSITA instrument on board Spectrum-Roentgen-Gamma (SRG) has completed four scans of the X-ray sky, leading to the detection of almost one million X-ray sources in eRASS1 alone, including multiple new X-ray binary candidates. We report on analysis of the X-ray binary 1eRASS J085039.9‑421151, using a ∼55 ks long NuSTAR observation, following i…
New interpretation of the two hard X-ray sources IGR J17503-2636 and IGR J17507-2647
Ponti, G.; Sidoli, L.; Esposito, P. +4 more
We report on the results of X-ray observations (XMM–Newton, INTEGRAL and Swift) of two hard X-ray sources, IGR J17503-2636 and IGR J17507-2647, whose nature is not fully elucidated in the literature. Three XMM–Newton observations covered the field of IGR J17503-2636, in 2020 and twice in 2023. The analysis of the two XMM–Newton observations perfor…
Extragalactic magnetar giant flare GRB 231115A: Insights from Fermi/GBM observations
Goldstein, Adam; Kouveliotou, Chryssa; Younes, George +22 more
Magnetar giant flares (MGFs) are the extremely short, energetic transients originating from highly magnetized neutron stars. When observed in nearby galaxies, these rare events are nearly indistinguishable from cosmological short gamma-ray bursts. We present the analysis of GRB 231115A, a candidate extragalactic MGF observed by Fermi/GBM and local…
New insights into the proton precipitation sites in solar flares
Krucker, Säm; Battaglia, Andrea Francesco
Aims. We revisit the Reuven Ramaty High Energy Solar Spectrocopy Imager (RHESSI) γ-ray observations of the extraordinary GOES X25 flare SOL2003-10-28T11:10 to investigate previously reported conclusions that flare-accelerated electrons and protons precipitate along spatially separated flare loops. Methods. In contrast to previous works that recons…
The aluminium-26 distribution in a cosmological simulation of a Milky Way-type Galaxy
Yagüe López, A.; Lugaro, M.; Wehmeyer, B. +1 more
Context. The 1.8 MeV γ-rays corresponding to the decay of the radioactive isotope 26Al (with a half-life of 0.72 Myr ) have been observed by the SPI detector on the INTEGRAL spacecraft and extensively used as a tracer of star formation and current nucleosynthetic activity in the Milky Way Galaxy. Further information is encoded in the ob…
Timing and spectral studies of the Be/X-ray binary EXO 2030+375 using Insight-HXMT observations
Bu, Qing-Cui; Santangelo, Andrea; Ji, Long +5 more
We report the results of a X-ray spectral and timing analysis of the high mass X-ray binary EXO 2030+375 during the 2021 type-II outburst based on Insight-HXMT observations. We confirm that pulsations can be detected in the energy band of 1‑150 keV. The pulse profile shows both energy and luminosity dependence and variability. We observed transiti…
A simplified approach for reproducing fully relativistic spectra in X-ray binary systems: Application to Cygnus X-1
Papavasileiou, Th. V.; Kosmas, O.; Kosmas, T. S.
Context. General relativistic effects are strong near the black hole of an X-ray binary and significantly impact the total energy released in the innermost accretion disk's region. The simple pseudo-Newtonian solution in the standard disk model cannot replenish for effects such as light-bending, gravitational redshift, and Doppler boost. These can…
Discovery of a variable energy-dependent X-ray polarization in the accreting neutron star GX 5−1
Kaaret, Philip; Wu, Kinwah; Steiner, James F. +116 more
We report on the coordinated observations of the neutron star low-mass X-ray binary (NS-LMXB) GX 5−1 in X-rays (IXPE, NICER, NuSTAR, and INTEGRAL), optical (REM and LCO), near-infrared (REM), mid-infrared (VLT VISIR), and radio (ATCA). This Z-source was observed by IXPE twice in March-April 2023 (Obs. 1 and 2). In the radio band the source was det…