Search Publications
A cut-off in the TeV gamma-ray spectrum of the SNR Cassiopeia A
Maraschi, L.; Covino, S.; Antonelli, L. A. +140 more
It is widely believed that the bulk of the Galactic cosmic rays is accelerated in supernova remnants (SNRs). However, no observational evidence of the presence of particles of PeV energies in SNRs has yet been found. The young historical SNR Cassiopeia A (Cas A) appears as one of the best candidates to study acceleration processes. Between 2014 De…
Extreme jet ejections from the black hole X-ray binary V404 Cygni
Gurwell, M.; Russell, D. M.; Fender, R. +14 more
We present simultaneous radio through sub-mm observations of the black hole X-ray binary (BHXB) V404 Cygni during the most active phase of its June 2015 outburst. Our 4 h long set of overlapping observations with the Very Large Array, the Sub-millimeter Array and the James Clerk Maxwell Telescope (SCUBA-2) covers eight different frequency bands (i…
Luminosity dependence of the cyclotron line and evidence for the accretion regime transition in V 0332+53
Doroshenko, Victor; Tsygankov, Sergey S.; Mushtukov, Alexander A. +4 more
We report on the analysis of NuSTAR observations of the Be-transient X-ray pulsar V 0332+53 during the giant outburst in 2015 and another minor outburst in 2016. We confirm the cyclotron-line energy-luminosity correlation previously reported in the source and the line energy decrease during the giant outburst. Based on 2016 observations, we find t…
Swift observations of V404 Cyg during the 2015 outburst: X-ray outflows from super-Eddington accretion
Altamirano, D.; Sanna, A.; Knigge, C. +11 more
The black hole (BH) binary V404 Cyg entered the outburst phase in 2015 June after 26 yr of X-ray quiescence, and with its behaviour broke the outburst evolution pattern typical of most BH binaries. We observed the entire outburst with the Swift satellite and performed time-resolved spectroscopy of its most active phase, obtaining over a thousand s…
The black hole binary V404 Cygni: a highly accreting obscured AGN analogue
Motta, S. E.; Sánchez-Fernández, C.; Kuulkers, E. +2 more
Typical black hole binaries in outburst show spectral states and transitions, characterized by a clear connection between the inflow on to the black hole and outflows from its vicinity. The transient stellar mass black hole binary V404 Cyg apparently does not fit in this picture. Its outbursts are characterized by intense flares and intermittent p…
New hard X-ray sources discovered in the ongoing INTEGRAL Galactic plane survey after 14 yr of observations
Sunyaev, Rashid A.; Tsygankov, Sergey S.; Lutovinov, Alexander A. +3 more
The International Gamma-Ray Astrophysics Laboratory (INTEGRAL) continues to successfully work in orbit after its launch in 2002. The mission provides the deepest ever survey of hard X-ray sources throughout the Galaxy at energies above 20 keV. We report on a catalogue of new hard X-ray source candidates based on the latest sky maps comprising 14 y…
Flares, wind and nebulae: the 2015 December mini-outburst of V404 Cygni
Ponti, G.; Dhillon, V. S.; Charles, P. A. +22 more
After more than 26 years in quiescence, the black hole transient V404 Cyg went into a luminous outburst in 2015 June, and additional activity was detected in late December of the same year. Here, we present an optical spectroscopic follow-up of the December mini-outburst, together with X-ray, optical and radio monitoring that spanned more than a m…
Multicolour modelling of SN 2013dx associated with GRB 130702A★
Minaev, P. Yu.; Pozanenko, A. S.; Ehgamberdiev, Sh. A. +13 more
We present optical observations of SN 2013dx, related to the Fermi burst GRB 130702A, which occurred at red shift z = 0.145. It is the second-best sampled gamma-ray burst (GRB)/supernova (SN) after SN 1998bw. The observational light curves contain more than 280 data points in the uBgrRiz filters until 88 d after the burst, and the data were collec…
High-precision optical polarimetry of the accreting black hole V404 Cyg during the 2015 June outburst
Miles-Páez, Paulo A.; Piirola, Vilppu; Tsygankov, Sergey S. +4 more
Our simultaneous three-colour (BVR) polarimetric observations of the low-mass black hole X-ray binary V404 Cyg show a small but statistically significant change of polarization degree (Δp ∼ 1 per cent) between the outburst in 2015 June and the quiescence. The polarization of V404 Cyg in the quiescent state agrees within the errors with that of the…
An atlas of exotic variability in IGR J17091-3624: a comparison with GRS 1915+105
Court, J. M. C.; Altamirano, D.; Belloni, T. +5 more
We performed an analysis of all Rossi X-ray Timing Explorer observations of the low-mass X-ray binary (LMXB) and black hole candidate IGR J17091-3624 during the 2011-2013 outburst of the source. By creating light curves, hardness-intensity diagrams and power density spectra of each observation, we have created a set of nine variability 'classes' t…