Search Publications
44Ti ejecta in young supernova remnants
Diehl, Roland; Greiner, Jochen; Siegert, Thomas +2 more
Context. Tracing unstable isotopes produced in supernova nucleosynthesis provides a direct diagnostic of supernova explosion physics. Theoretical models predict an extensive variety of scenarios, which can be constrained through observations of the abundant isotopes 56Ni and 44Ti. Direct evidence of the latter was previously …
Burst-induced coronal cooling in GS 1826-24. The clock wagging its tail
Sánchez-Fernández, C.; Kuulkers, E.; Poutanen, J. +2 more
Type I X-ray bursts in GS 1826-24, and in several other systems, may induce cooling of the hot inner accretion flow that surrounds the bursting neutron star. Given that GS 1826-24 remained persistently in the hard state over the period 2003-2008 and presented regular bursting properties, we stacked the spectra of the X-ray bursts detected by INTEG…
An underlying clock in the extreme flip-flop state transitions of the black hole transient Swift J1658.2-4242
Nandra, K.; Ponti, G.; Miller-Jones, J. C. A. +8 more
Aims: Flip-flops are top-hat-like X-ray flux variations, which have been observed in some transient accreting black hole binary systems, and feature simultaneous changes in the spectral hardness and the power density spectrum (PDS). They occur at a crucial time in the evolution of these systems, when the accretion disc emission starts to domi…
Cyclotron line energy in Hercules X-1: stable after the decay
Harrison, F.; Ducci, L.; Wilms, J. +6 more
We summarize the results of a dedicated effort made between 2012 and 2019 to follow the evolution of the cyclotron line in Her X-1 through repeated NuSTAR observations. The previously observed nearly 20-year-long decay of the cyclotron line energy has ended in 2012: from then on, the pulse-phase-averaged flux-corrected cyclotron line energy has re…
High-energy characteristics of the accretion-powered millisecond pulsar IGR J17591-2342 during its 2018 outburst. XMM-Newton, NICER, NuSTAR, and INTEGRAL view of the 0.3-300 keV X-ray band
Tsygankov, S. S.; Kuiper, L.; Poutanen, J. +4 more
IGR J17591-2342 is an accreting millisecond X-ray pulsar, discovered with INTEGRAL, which went into outburst around July 21, 2018. To better understand the physics acting in these systems during the outburst episode, we performed detailed temporal-, timing-, and spectral analyses across the 0.3-300 keV band using data from NICER, XMM-Newton, NuSTA…
X-ray absorption in INTEGRAL active galactic nuclei. Host galaxy inclination
Ubertini, P.; Malizia, A.; Bassani, L. +2 more
In this work the INTEGRAL hard X-ray selected sample of active galactic nuclei (AGN) has been used to investigate the possible contribution of absorbing material distributed within the host galaxies to the total amount of NH measured in the X-ray band. We collected all the available axial ratio measurements of the galaxies hosting our A…
The long-term enhanced brightness of the magnetar 1E 1547.0-5408
Enoto, Teruaki; Esposito, Paolo; Rea, Nanda +6 more
We present the evolution of the X-ray emission properties of the magnetar 1E 1547.0-5408 since February 2004 over a time period covering three outbursts. We analyzed new and archival observations taken with the Swift, NuSTAR, Chandra, and XMM-Newton X-ray satellites. The source has been observed at a relatively steady soft X-ray flux of ≈10-1…
V363 Cassiopeiae: a new lithium-rich Galactic Cepheid
Clementini, G.; Ripepi, V.; Molinaro, R. +8 more
Context. Classical Cepheids (DCEPs) are important astrophysical objects not only as standard candles in the determination of the cosmic distance ladder, but also as a testbed for the stellar evolution theory. This is based on the strict connection between their pulsation (period(s) and amplitudes) and stellar parameters (luminosity, mass, effectiv…
Water megamaser emission in hard X-ray selected AGN
Ubertini, P.; Malizia, A.; Bassani, L. +4 more
Context. Water megamaser emission at 22 GHz has proven to be a powerful tool for astrophysical studies of active galactic nuclei (AGN) because it allows an accurate determination of the mass of the central black hole and of the accretion disc geometry and dynamics. However, after searches among thousands of galaxies, only about 200 of them have sh…
Hard X-ray properties of radio-selected blazars
Gehrels, N.; Wilms, J.; Kadler, M. +6 more
Context. Hard X-ray properties of beamed active galactic nuclei have been published in the 105-month Swift/BAT catalog, but there have not been any studies carried out so far on a well-defined, radio-selected sample of low-peaked blazars in the hard X-ray band.
Aims: Using the statistically complete MOJAVE-1 sample, we aim to determine the ha…