Search Publications
Simultaneous Millimetre-wave and X-ray monitoring of the Seyfert galaxy NGC 7469
Kaspi, Shai; Laor, Ari; Mehdipour, Missagh +6 more
We report on daily monitoring of the Seyfert galaxy NGC 7469, around 95 and 143 GHz, with the IRAM (Institut de Radioastronomie Millimetrique) 30- m radio telescope, and with the Swift X-ray and UV/optical telescopes, over an overlapping period of 45 d. The source was observed on 36 d with IRAM, and the flux density in both mm bands was on average…
The X-ray emissivity of low-density stellar populations
van den Berg, M.; Heinke, C. O.; Cohn, H. N. +17 more
The dynamical production of low-mass X-ray binaries and brighter cataclysmic variables (CVs) in dense globular clusters is well-established. We investigate how the X-ray emissivity of fainter X-ray binaries (principally CVs and coronally active binaries) varies between different environments. We compile calculations (largely from the literature) o…
Impact of the reflection model on the estimate of the properties of accreting black holes
Tripathi, Ashutosh; Bambi, Cosimo; Liu, Honghui
Relativistic reflection features in the X-ray spectra of black hole binaries and active galactic nuclei originate from illumination of the inner part of the accretion disc by a hot corona. In the presence of high quality data and with the correct astrophysical model, X-ray reflection spectroscopy can be quite a powerful tool to probe the strong gr…
Multiwavelength power-spectrum analysis of NGC 5548
Papadakis, I. E.; Dovčiak, M.; Kammoun, E. S. +1 more
NGC 5548 was recently monitored intensively from NIR to X-rays as part of the STORM campaign. Its disc emission was found to lag behind the observed X-rays, while the measured time lag was increasing with wavelength. These results are consistent with the assumption that short-term variability in AGN emission is driven by the X-ray illumination of …
Long tidal tails in merging galaxies and their implications
Bell, Eric F.; Valls-Gabaud, David; Duc, Pierre-Alain +8 more
We investigate the properties of long tidal tails using the largest to date sample of 461 merging galaxies with $\log (M_\ast /\rm M_\odot)\ge 9.5$ within 0.2 ≤ z ≤ 1 from the COSMOS survey in combination with Hubble Space Telescope imaging data. Long tidal tails can be briefly divided into three shape types: straight (41 per cent), curved (47 per…
Near-infrared variability in dusty white dwarfs: tracing the accretion of planetary material
Xu, Siyi; von Hippel, Ted; Su, Kate Y. L. +4 more
The inwards scattering of planetesimals towards white dwarfs is expected to be a stochastic process with variability on human time-scales. The planetesimals tidally disrupt at the Roche radius, producing dusty debris detectable as excess infrared emission. When sufficiently close to the white dwarf, this debris sublimates and accretes on to the wh…
Properties of giant molecular clouds in the strongly barred galaxy NGC 1300
Ohta, Kouji; Maeda, Fumiya; Fujimoto, Yusuke +1 more
Star formation activity depends on galactic-scale environments. To understand the variations in star formation activity, comparing the properties of giant molecular clouds (GMCs) among environments with different star formation efficiency (SFE) is necessary. We thus focus on a strongly barred galaxy to investigate the impact of the galactic enviro…
The nature of CR7 revealed with MUSE: a young starburst powering extended Ly α emission at z = 6.6
Richard, Johan; Nanayakkara, Themiya; Sobral, David +11 more
CR7 is among the most luminous Ly α emitters (LAEs) known at z = 6.6 and consists of at least three UV components that are surrounded by Ly α emission. Previous studies have suggested that it may host an extreme ionizing source. Here, we present deep integral field spectroscopy of CR7 with VLT/Multi Unit Spectroscopic Explorer (MUSE). We measure e…
NGTS clusters survey - II. White-light flares from the youngest stars in Orion
Jackman, James A. G.; Wheatley, Peter J.; Moyano, Maximiliano +18 more
We present the detection of high-energy white-light flares from pre-main-sequence stars associated with the Orion Complex, observed as part of the Next Generation Transit Survey (NGTS). With energies up to 5.2 × 1035 erg these flares are some of the most energetic white-light flare events seen to date. We have used the NGTS observations…
Constraining Type Iax supernova progenitor systems with stellar population age dating
Foley, Ryan J.; Rest, Armin; Fong, Wen-fai +6 more
Type Iax supernovae (SNe Iax) are the most common class of peculiar SNe. While they are thought to be thermonuclear white-dwarf (WD) SNe, SNe Iax are observationally similar to, but distinct from SNe Ia. Unlike SNe Ia, where roughly 30 per cent occur in early-type galaxies, only one SN Iax has been discovered in an early-type galaxy, suggesting a …