Search Publications
Sgr B2 hard X-ray emission with INTEGRAL after 2009: still detectable?
Krivonos, Roman; Clavel, Maïca; Kuznetsova, Ekaterina +1 more
The molecular cloud Sgr B2 is a natural Compton mirror in the Central Molecular Zone. It is believed that the observed fading of the Sgr B2 X-ray emission in continuum and the Fe Kα 6.4 keV line indicates past X-ray flare activity of the supermassive black hole Sgr A⋆. Sgr B2 was investigated by the INTEGRAL observatory in the hard X-ra…
Characterizing eclipsing white dwarf M dwarf binaries from multiband eclipse photometry
Dhillon, V. S.; Parsons, Steven G.; Breedt, E. +10 more
With the prevalence of wide-field, time-domain photometric sky surveys, the number of eclipsing white dwarf (WD) systems being discovered is increasing dramatically. An efficient method to follow these up will be key to determining any population trends and finding any particularly interesting examples. We demonstrate that multiband eclipse photom…
UVIT view of Centaurus A: a detailed study on positive AGN feedback
Mathew, Blesson; Paul, K. T.; Stalin, C. S. +4 more
Supermassive black holes at the centre of active galactic nuclei (AGNs) produce relativistic jets that can affect the star formation characteristics of the AGN hosts. Observations in the ultraviolet (UV) band can provide an excellent view of the effect of AGN jets on star formation. Here, we present a census of star formation properties in the Nor…
Searching for stellar flares from low-mass stars using ASKAP and TESS
Ramsay, Gavin; Gallagher, Peter T.; Kaplan, David L. +7 more
Solar radio emission at low frequencies (<1 GHz) can provide valuable information on processes driving flares and coronal mass ejections (CMEs). Radio emission has been detected from active M dwarf stars, suggestive of much higher levels of activity than previously thought. Observations of active M dwarfs at low frequencies can provide informat…
Cycle dependence of a quasi-biennial variability in the solar interior
Broomhall, A. -M.; Jain, K.; Tripathy, S. C. +3 more
We investigated the solar cycle dependence on the presence and periodicity of the Quasi-Biennial Oscillation (QBO). Using helioseismic techniques, we used solar oscillation frequencies from the Global Oscillations Network Group (GONG), Michelson Doppler Imager (MDI), and Helioseismic and Magnetic Imager (HMI) in the intermediate-degree range to in…
X-ray intraday variability and power spectral density profiles of the blazar 3C 273 with XMM-Newton during 2000-2021
Gupta, Alok C.; Wiita, Paul J.; Ward, Martin +3 more
We present X-ray intraday variability and power spectral density (PSD) analyses of the longest 23 pointed XMM-Newton observations of the blazar 3C 273 that were taken during 2000-2021. These good time intervals contain between 5 and 24.6 h of data. Variability has been estimated in three energy bands: 0.2-2 keV (soft), 2-10 keV (hard), and 0.2-10 …
ULX pulsar Swift J0243.6+6124 observations with NuSTAR: dominance of reflected emission in the super-Eddington state
Gilfanov, M. R.; Tsygankov, S. S.; Filippova, E. V. +1 more
We report the discovery of the bright reflected emission component in the super-Eddington state of the ultraluminous X-ray pulsar Swift J0243.6+6124, based on the NuSTAR observations of the source during its 2017 outburst. The flux of the reflected emission is weakly variable over the pulsar phase while the direct emission shows significantly larg…
Zodiacal exoplanets in time (ZEIT) XII: a directly imaged planetary-mass companion to a young Taurus M dwarf star
Kuzuhara, M.; Tamura, M.; Kudo, T. +21 more
We report the discovery of a resolved (0.9 arcsec) substellar companion to a member of the 1-5 Myr Taurus star-forming region. The host star (2M0437) is a single mid-M type (Teff ≈ 3100 K) dwarf with a position, space motion, and colour-magnitude that support Taurus membership, and possible affiliation with a ~2.5-Myr-old subgroup. A co…
Unveiling the disc structure in ultraluminous X-ray source NGC 55 ULX-1
Fabian, A. C.; Pinto, C.; Di Salvo, T. +11 more
Ultraluminous X-ray sources (ULXs) are the most extreme among X-ray binaries in which the compact object, a neutron star or a black hole, accretes matter from the companion star, and exceeds a luminosity of $10^{39} \ \rm erg \, s^{-1}$ in the X-ray energy band alone. Despite two decades of studies, it is still not clear whether ULX spectral trans…
A triple star origin for T Pyx and other short-period recurrent novae
Knigge, C.; Toonen, S.; Boekholt, T. C. N.
Recurrent novae are star systems in which a massive white dwarf accretes material at such a high rate that it undergoes thermonuclear runaways every 1-100 yr. They are the only class of novae in which the white dwarf can grow in mass, making some of these systems strong Type Ia supernova progenitor candidates. Almost all known recurrent novae are …