Search Publications
Superflare on a rapidly-rotating solar-type star captured in X-rays
Sunyaev, Rashid; Gilfanov, Marat; Bikmaev, Ilfan +5 more
In this work, we studied X-ray source SRGe J021932.4‑040154 (SRGe J021932), which we associated with a single X-ray active star of spectral class G2V-G4V and the rotational period
Evidence for 3XMM J185246.6+003317 as a massive magnetar with a low magnetic field
Rodrigues, Claudia V.; de Lima, Rafael C. R.; Pereira, Jonas P. +10 more
3XMM J185246.6+003317 is a transient magnetar located in the vicinity of the supernova remnant Kes79. So far, observations have only set upper limits to its surface magnetic field and spindown, and there is no estimate for its mass and radius. Using ray-tracing modelling and Bayesian inference for the analysis of several light curves spanning a pe…
A multiwavelength study of the most distant gamma-ray detected BL Lacertae object 4FGL J1219.0+3653 (z = 3.59)
Domínguez, A.; Gallego, J.; Cardiel, N. +3 more
BL Lac objects are a class of jetted active galactic nuclei that do not exhibit or have weak emission lines in their optical spectra. Recently, the first γ-ray emitting BL Lac beyond
The challenge of identifying INTEGRAL sources on the Galactic plane
Ubertini, Pietro; Bazzano, Angela; Fiocchi, Mariateresa +6 more
The International Gamma-ray Astrophysics Laboratory (INTEGRAL) has been surveying the sky above 20 keV since its launch in 2002 providing new insights into the nature of the sources that populate our Universe at soft γ-ray energies. The latest IBIS/ISGRI survey lists 929 hard X-ray sources, of which 113 are reported as unidentified, i.e. lacking a…
Response of the Fe Kα line emission to the X-ray continuum variability in the changing-look active galactic nucleus NGC 1566
Shu, X. W.; Wang, J. X.; Jiang, N. +5 more
NGC 1566 is a changing look AGN known to exhibit recurrent X-ray outbursts with each lasting for several years. The most recent X-ray outburst is observed on 2018, with a substantial increase of 2-10 keV flux by a factor of ∼24 than the historical minimum. We re-analyze the XMM-Newton and NuSTAR observations covering the pre-outburst, outburst and…
Redshift evolution of X-ray spectral index of quasars observed by XMM-NEWTON/SDSS
Misra, R.; Hayman, Z. M.; Shehata, SH. M. +2 more
We study the X-ray spectral evolution of quasars with red-shift using a sample of 1280 quasars constructed by cross-referencing the XMM-Newton 3 XMM - DR 7 and the optical SDSS-DR14 catalogues. The sources were selected to have a minimum detected X-ray counts >600 and which were not affected by high background. The sample redshift distribution …
In-flight calibration of the Insight-Hard X-ray Modulation Telescope
Zhang, Shu; Li, Xiaobo; Tuo, Youli +19 more
We present the calibration of the Insight-Hard X-ray Modulation Telescope (Insight-HXMT) X-ray satellite, which can be used to perform timing and spectral studies of bright X-ray sources. Insight-HXMT carries three main payloads onboard: the High Energy X-ray telescope (HE), the Medium Energy X-ray telescope (ME) and the low Energy X-ray telescope…
Multi-wavelength observations of the BL Lac object Fermi J1544-0649: One year after its awakening
Kong, A. K. H.; Tam, P. H. T.; Mao, J. +15 more
We report observations of a transient source Fermi J1544-0649 from radio to γ-rays. Fermi J1544-0649 was discovered by the Fermi-LAT in May 2017. Follow-up Swift-XRT observations revealed three flaring episodes through March 2018, and the peak X-ray flux is about 103 higher than the ROSAT all-sky survey (RASS) flux upper limit. Optical …
Interstellar gas and X-rays toward the Young supernova remnant RCW 86; pursuit of the origin of the thermal and non-thermal X-ray
Fukui, Y.; Mitsuishi, I.; Reynoso, E. M. +13 more
We have analyzed the atomic and molecular gas using the 21 cm HI and 2.6/1.3 mm CO emissions toward the young supernova remnant (SNR) RCW 86 in order to identify the interstellar medium with which the shock waves of the SNR interact. We have found an HI intensity depression in the velocity range between -46 and - 28 kms-1 toward the SNR…
Swift discoveries of new populations of extremely long duration high energy transient
Levan, A. J.
Recent observations with Swift have begun to uncover γ-ray transients whose total energies are comparable to those of gamma-ray bursts (GRB), but have a duration an order of magnitude or more longer than the bulk of the GRB population. Some are suggested to form a new population of ultra-long GRBs, with a mean duration around 104 s, whi…