Search Publications
Discovery of a new accreting millisecond X-ray pulsar in the globular cluster NGC 2808
Sanna, A.; Rea, N.; Ferrigno, C. +6 more
We report on the discovery of coherent pulsations at a period of 2.9 ms from the X-ray transient MAXI J0911-655 in the globular cluster NGC 2808. We observed X-ray pulsations at a frequency of 339.97 Hz in three different observations of the source performed with XMM-Newton and NuSTAR during the source outburst. This newly discovered accreting mil…
The β Pictoris association low-mass members: Membership assessment, rotation period distribution, and dependence on multiplicity
Lanzafame, A. C.; Messina, S.; Zhang, L. +6 more
Context. Low-mass members of young loose stellar associations and open clusters exhibit a wide spread of rotation periods. Such a spread originates from the distributions of masses and initial rotation periods. However, multiplicity can also play a significant role.
Aims: We aim to investigate the role played by physical companions in multipl…
The β Pictoris association: Catalog of photometric rotational periods of low-mass members and candidate members
Messina, S.; Medhi, B. J.; Zhang, L. +19 more
Aims: We intended to compile the most complete catalog of bona fide members and candidate members of the β Pictoris association, and to measure their rotation periods and basic properties from our own observations, public archives, and exploring the literature.
Methods: We carried out a multi-observatories campaign to get our own photome…
The 2015 outburst of the accretion-powered pulsar IGR J00291+5934: INTEGRAL and Swift observations
Stella, L.; Ferrigno, C.; Bozzo, E. +5 more
The pulsar IGR J00291+5934 is the fastest-known accretion-powered X-ray pulsar, discovered during a transient outburst in 2004. In this paper, we report on INTEGRAL and Swift observations during the 2015 outburst, which lasts for 25 d. The source has not been observed in outburst since 2008, suggesting that the long-term accretion rate has decreas…
X-ray burst-induced spectral variability in 4U 1728-34
Sánchez-Fernández, C.; Kuulkers, E.; Poutanen, J. +1 more
Aims: INTEGRAL has been monitoring the Galactic center region for more than a decade. Over this time it has detected hundreds of type-I X-ray bursts from the neutron star low-mass X-ray binary 4U 1728-34, also known as the slow burster. Our aim is to study the connection between the persistent X-ray spectra and the X-ray burst spectra in a br…
Hard X-ray variability of V404 Cygni during the 2015 outburst
Motta, S. E.; Sánchez-Fernández, C.; Kuulkers, E. +1 more
Aims: Hard X-ray spectra of black hole binaries (BHB) are produced by Comptonization of soft seed photons by hot electrons near the black hole. The slope of the resulting energy spectra is governed by two main parameters: the electron temperature (Te) and optical depth (τ) of the emitting plasma. Given the extreme brightness of V40…
First multi-wavelength campaign on the gamma-ray-loud active galaxy IC 310
Maraschi, L.; Covino, S.; Antonelli, L. A. +161 more
Context. The extragalactic very-high-energy gamma-ray sky is rich in blazars. These are jetted active galactic nuclei that are viewed at a small angle to the line-of-sight. Only a handful of objects viewed at a larger angle are so far known to emit above 100 GeV. Multi-wavelength studies of such objects up to the highest energies provide new insig…
INTEGRAL IBIS, SPI, and JEM-X observations of LVT151012
Sunyaev, R.; Hanlon, L.; Mereghetti, S. +18 more
During the first observing run of LIGO, two gravitational wave events and one lower-significance trigger (LVT151012) were reported by the LIGO/Virgo collaboration. At the time of LVT151012, the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) was pointing at a region of the sky coincident with the high localization probability area of th…
Multiwavelength variability study and search for periodicity of PKS 1510-089
Tagliaferri, G.; Ghisellini, G.; Pian, E. +14 more
Context. Blazars are the most luminous and variable active galactic nuclei (AGNs). They are thus excellent probes of accretion and emission processes close to the central engine.
Aims: We concentrate here on PKS 1510-089 (z = 0.36), a blazar belonging to the flat-spectrum radio quasar subclass, an extremely powerful gamma-ray source and one o…
Inversion of the decay of the cyclotron line energy in Hercules X-1
Harrison, F.; Klochkov, D.; Wilms, J. +3 more
Recent observations of Her X-1 with NuSTAR and INTEGRAL in 2016 have provided evidence that the 20-year decay of the cyclotron line energy found between 1996 and 2015 has ended and that an inversion with a new increase, possibly similar to the one observed around 1990-1993, has started. We consider this a strong motivation for further observations…