Search Publications
Thermal luminosities of cooling neutron stars
Zyuzin, D. A.; Shibanov, Yu A.; Potekhin, A. Y. +2 more
Ages and thermal luminosities of neutron stars, inferred from observations, can be interpreted with the aid of the neutron star cooling theory to gain information on the properties of superdense matter in neutron-star interiors. We present a survey of estimated ages, surface temperatures, and thermal luminosities of middle-aged neutron stars with …
X-ray detected AGN in SDSS dwarf galaxies
Birchall, Keir L.; Watson, M. G.; Aird, J.
In this work we present a robust quantification of X-ray selected AGN in local (z ≤ 0.25) dwarf galaxies (M_* ≤ 3 × 10^9 M_⊙ ). We define a parent sample of 4331 dwarf galaxies found within the footprint of both the MPA-JHU galaxy catalogue (based on SDSS DR8) and 3XMM DR7, performed a careful review of the data to remove misidentifications and pr…
Ram pressure stripping candidates in the coma cluster: evidence for enhanced star formation
Parker, Laura C.; Roberts, Ian D.
The Coma cluster is the nearest massive (M ≳ 1015 M⊙) galaxy cluster, making it an excellent laboratory to probe the influence of the cluster environment on galaxy star formation. Here, we present a sample of 41 galaxies with disturbed morphologies consistent with ram pressure stripping. These galaxies are identified visually using high…
To TDE or not to TDE: the luminous transient ASASSN-18jd with TDE-like and AGN-like qualities
Gromadzki, M.; Kochanek, C. S.; Foley, R. J. +26 more
We present the discovery of ASASSN-18jd (AT 2018bcb), a luminous optical/ultraviolet(UV)/X-ray transient located in the nucleus of the galaxy 2MASX J22434289-1659083 at z = 0.1192. Over the year after discovery, Swift UltraViolet and Optical Telescope (UVOT) photometry shows the UV spectral energy distribution of the transient to be well modelled …
The LX-Luv-Lradio relation and corona-disc-jet connection in optically selected radio-loud quasars
Brandt, W. N.; Xue, Y. Q.; Luo, B. +3 more
Radio-loud quasars (RLQs) are more X-ray luminous than predicted by the X-ray-optical/UV relation (i.e. $L_\mathrm{x}\propto L_\mathrm{uv}^\gamma$) for radio-quiet quasars (RQQs). The excess X-ray emission depends on the radio-loudness parameter (R) and radio spectral slope (αr). We construct a uniform sample of 729 optically selected R…
The unusual broad-band X-ray spectral variability of NGC 1313 X-1 seen with XMM-Newton, Chandra, and NuSTAR
Harrison, F. A.; Stern, D.; Fabian, A. C. +19 more
We present results from the major coordinated X-ray observing programme on the ULX NGC 1313 X-1 performed in 2017, combining XMM-Newton, Chandra, and NuSTAR, focusing on the evolution of the broad-band (∼0.3-30.0 keV) continuum emission. Clear and unusual spectral variability is observed, but this is markedly suppressed above ∼10-15 keV, qualitati…
Searching for ultra-fast outflows in AGN using variability spectra
Schartel, N.; Santos-Lleó, M.; Buisson, D. J. K. +9 more
We present a qualitative search for ultra-fast outflows (UFOs) in excess variance spectra of radio-quiet active galactic nuclei (AGNs). We analyse 42 sources from the spectroscopic UFO detection sample, and an additional 22 different sources from the variability sample. A total of 58 sources have sufficient observational data from XMM-Newton EPIC-…
The soft X-ray excess: NLS1s versus BLS1s
Gliozzi, Mario; Williams, James K.
The soft X-ray excess - the excess of X-rays below 2 keV with respect to the extrapolation of the hard X-ray spectral continuum model - is a very common feature among type 1 active galactic nuclei (AGNs); yet the nature of the soft X-ray excess is still poorly understood and hotly debated. To shed some light on this issue, we have measured in a mo…
The 2020 April-June super-outburst of OJ 287 and its long-term multiwavelength light curve with Swift: binary supermassive black hole and jet activity
Komossa, S.; Grupe, D.; Parker, M. L. +4 more
We report detection of a very bright X-ray-UV-optical outburst of OJ 287 in 2020 April-June, the second brightest since the beginning of our Swift multiyear monitoring in late 2015. It is shown that the outburst is predominantly powered by jet emission. Optical-UV-X-rays are closely correlated, and the low-energy part of the XMM-Newton spectrum di…
XMM-Newton campaign on ultraluminous X-ray source NGC 1313 X-1: wind versus state variability
Guainazzi, M.; Fabian, A. C.; Pinto, C. +12 more
Most ultraluminous X-ray sources (ULXs) are thought to be powered by neutron stars and black holes accreting beyond the Eddington limit. If the compact object is a black hole or a neutron star with a magnetic field ≲1012 G, the accretion disc is expected to thicken and launch powerful winds driven by radiation pressure. Evidence of such…