Search Publications
IGR J18249-3243: a new GeV-emitting FR II and the emerging population of high-energy radio galaxies
Ricci, R.; Wieringa, M. H.; Giroletti, M. +10 more
The advent of new all-sky radio surveys such as the VLA Sky Survey and the Rapid ASKAP Continuum Survey, performed with the latest generation radio telescopes, is opening new possibilities on the classification and study of extragalactic γ-ray sources, specially the underrepresented ones like radio galaxies. In particular, the enhanced sensitivity…
Transient two-pole accretion in the polar V496 UMa
Garnavich, P. M.; Kennedy, M. R.; Littlefield, C.
We report XMM-Newton and TESS observations of V496 UMa, an AM Herculis-type cataclysmic variable. The XMM-Newton observation reveals that at times, two poles on the white dwarf accrete simultaneously, but accretion on to the secondary magnetic pole is erratic and can nearly cease in less than one binary orbit (1.5 h). Modelling of the X-ray spectr…
Impacts of zonal winds on planetary oscillations and Saturn ring seismology
Fuller, Jim; Dewberry, Janosz W.; Mankovich, Christopher R.
The excitation of density and bending waves in Saturn's C ring by planetary oscillation modes presents a unique opportunity to learn about gas giant interiors and rotation. However, theoretical complications related to Saturn's rapid and differential rotation pose a barrier to the full utilization of ring wave detections. We calculate oscillation …
Fundamental effective temperature measurements for eclipsing binary stars - II. The detached F-type eclipsing binary CPD-54 810
Maxted, P. F. L.; Southworth, J.; Tan, T. G. +2 more
CPD-54 810 is a double-lined detached eclipsing binary containing two mid-F type dwarfs on an eccentric 26-d orbit. We perform a combined analysis of the extensive photometry obtained by the TESS space mission along with previously published observations to obtain a full orbital and physical solution for the system. We measure the following model-…
The XXL Survey - XLVIII. X-ray follow-up of distant XXL clusters: masses, scaling relations, and AGN contamination
Valtchanov, I.; Pierre, M.; Gastaldello, F. +11 more
We use deep follow-up XMM-Newton observations of six clusters discovered in the XXL Survey at z > 1 to gain robust measurements of their X-ray properties and to investigate the extent to which scaling relations at low redshift are valid at z > 1. This sample is unique as it has been investigated for active galactic nucleus (AGN) contaminatio…
The relation between X-ray and ultraviolet variability of quasars
Xie, Zhang-Liang; Cai, Zhen-Yi; Wang, Jun-Xian +2 more
The relation between X-ray and UV/optical variability in AGNs has been explored in many individual sources, however a large sample study is yet absent. Through matching the XMM-Newton serendipitous X-ray and UV source catalogs with SDSS quasars, we build a sample of 802 epoch-pairs of 525 quasars showing clear variability in logFX - log…
Spectroscopy of an extreme [O III] emitting active galactic nucleus at z = 3.212: implications for the reionization era
Feltre, Anna; Charlot, Stéphane; Shapley, Alice E. +4 more
Reionization-era galaxies often display intense nebular emission lines, both in rest-frame optical ([O III] + H β) and ultraviolet (UV; C III], C IV). How such strong nebular emission is powered remains unclear, with both active galactic nuclei (AGNs) and hot stars considered equally viable. The UV continuum slopes of these early systems tend to b…
The origin of the high-mass X-ray binary 4U 2206+54/BD+532790
Neuhäuser, R.; Mugrauer, M.; Stoyanov, K. A. +7 more
Based on the Gaia EDR3 astrometric parameters and our new systemic radial velocity of the high-mass X-ray binary 4U 2206+54/BD+532790, we studied the trace back motion of the system and propose that it originated in the subgroup of the Cepheus OB1 association (Age ~4-10 Myr) with its brightest star, BD+532820 (B0V; ${\cal L}$~104.7${\ca…
Spectroscopic and imaging observations of transient hot and cool loops by IRIS and SDO
Gupta, Girjesh R.; Nayak, Sushree S.
Coronal loops are the basic building blocks of the solar atmosphere and are observed on various length scales. However, their formation mechanism is still unclear. In this paper, we present spectroscopic and imaging observations of small-scale transients and the subsequent formation of transient loops. For this purpose, we have utilized the multiw…
MeerKAT radio observations of the neutron star low-mass X-ray binary Cen X-4 at low accretion rates
Fender, R.; Miller-Jones, J. C. A.; van den Eijnden, J. +4 more
Centaurus X-4 (Cen X-4) is a relatively nearby neutron star low-mass X-ray binary that showed outbursts in 1969 and 1979, but has not shown a full outburst since. Due to its proximity and sustained period of quiescence, it is a prime target to study the coupling between accretion and jet ejection in quiescent neutron star low-mass X-ray binaries. …