Search Publications
Discovery of pulsations from NGC 300 ULX1 and its fast period evolution
Haberl, F.; Vasilopoulos, G.; Maitra, C. +1 more
The supernova impostor SN 2010da located in the nearby galaxy NGC 300, later identified as a likely supergiant B[e] high-mass X-ray binary, was simultaneously observed by NuSTAR and XMM-Newton between 2016 December 16 and 20, over a total time span of ∼310 ks. We report the discovery of a strong periodic modulation in the X-ray flux with a pulse p…
Explaining changing-look AGN with state transition triggered by rapid mass accretion rate drop
Done, Chris; Noda, Hirofumi
We model the broad-band (optical/UV and X-ray) continuum spectrum of the `changing-look' active galactic nucleus (AGN) Mrk 1018, as it fades from Seyfert 1 to 1.9 in ∼ 8 years. The brightest spectrum, with Eddington ratio L/LEdd ∼ 0.08 has a typical type 1 AGN continuum, with a strong `soft X-ray excess' spanning between the UV and soft…
A physical model of the broad-band continuum of AGN and its implications for the UV/X relation and optical variability
Done, Chris; Kubota, Aya
We develop a new spectral model for the broad-band spectral energy distribution (SED) of active galactic nuclei (AGN). This includes an outer standard disc, an inner warm Comptonizing region to produce the soft X-ray excess and a hot corona. We tie these together energetically by assuming Novikov-Thorne emissivity, and use this to define a size sc…
Finding counterparts for all-sky X-ray surveys with NWAY: a Bayesian algorithm for cross-matching multiple catalogues
Salvato, M.; Buchner, J.; Nandra, K. +6 more
We release the AllWISE counterparts and Gaia matches to 106 573 and 17 665 X-ray sources detected in the ROSAT 2RXS and XMMSL2 surveys with |b| > 15°. These are the brightest X-ray sources in the sky, but their position uncertainties and the sparse multi-wavelength coverage until now rendered the identification of their counterparts a demanding…
Constraining the mass and radius of neutron stars in globular clusters
Heinke, C. O.; Ho, W. C. G.; Bogdanov, S. +4 more
We analyse observations of eight quiescent low-mass X-ray binaries in globular clusters and combine them to determine the neutron star mass-radius curve and the equation of state of dense matter. We determine the effect that several uncertainties may have on our results, including uncertainties in the distance, the atmosphere composition, the neut…
Systematic study of magnetar outbursts
Esposito, Paolo; Rea, Nanda; Coti Zelati, Francesco +2 more
We present the results of the systematic study of all magnetar outbursts observed to date, through a reanalysis of data acquired in about 1100 X-ray observations. We track the temporal evolution of the outbursts' soft X-ray spectral properties and the luminosities of the single spectral components as well as of the total emission. We model empiric…
BAT AGN Spectroscopic Survey - XII. The relation between coronal properties of active galactic nuclei and the Eddington ratio
Treister, E.; Bauer, F. E.; Paltani, S. +12 more
The bulk of the X-ray emission in active galactic nuclei (AGNs) is produced very close to the accreting supermassive black hole (SMBH), in a corona of hot electrons which up scatters optical and ultraviolet photons from the accretion flow. The cut-off energy (EC) of the primary X-ray continuum emission carries important information on t…
Evidence for a variable Ultrafast Outflow in the newly discovered Ultraluminous Pulsar NGC 300 ULX-1
Fabian, A. C.; Pinto, C.; Bachetti, M. +5 more
Ultraluminous pulsars are a definite proof that persistent super-Eddington accretion occurs in nature. They support the scenario according to which most Ultraluminous X-ray Sources (ULXs) are super-Eddington accretors of stellar mass rather than sub-Eddington intermediate mass black holes. An important prediction of theories of supercritical accre…
The SUrvey for Pulsars and Extragalactic Radio Bursts - I. Survey description and overview
Possenti, A.; Kramer, M.; Burgay, M. +19 more
We describe the Survey for Pulsars and Extragalactic Radio Bursts (SUPERB), an ongoing pulsar and fast transient survey using the Parkes radio telescope. SUPERB involves real-time acceleration searches for pulsars and single-pulse searches for pulsars and fast radio bursts. We report on the observational set-up, data analysis, multiwavelength/mess…
The 1.5 Ms observing campaign on IRAS 13224-3809 - I. X-ray spectral analysis
Harrison, F. A.; Fabian, A. C.; Miller, J. M. +16 more
We present a detailed spectral analysis of the recent 1.5 Ms XMM-Newton observing campaign on the narrow-line Seyfert 1 galaxy IRAS 13224-3809, taken simultaneously with 500 ks of NuSTAR data. The X-ray light curve shows three flux peaks, registering at about 100 times the minimum flux seen during the campaign, and rapid variability with a time-sc…