Search Publications
Star formation in the outskirts of DDO 154: a top-light IMF in a nearly dormant disc
Meurer, Gerhardt R.; Lagos, Claudia D. P.; Kroupa, Pavel +3 more
We present optical photometry of Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS)/Wide Field Camera (WFC) data of the resolved stellar populations in the outer disc of the dwarf irregular galaxy DDO 154. The photometry reveals that young main sequence (MS) stars are almost absent from the outermost H I disc. Instead, most are cluster…
Generation of a circumstellar gas disc by hot Jupiter WASP-12b
Frank, Adam; Dobbs-Dixon, Ian; Fossati, Luca +3 more
Observations of transiting extra-solar planets provide rich sources of data for probing the in-system environment. In the WASP-12 system, a broad depression in the usually bright Mg II h&k lines has been observed, in addition to atmospheric escape from the extremely hot Jupiter WASP-12b. It has been hypothesized that a translucent circumstella…
Formation time-scales for high-mass X-ray binaries in M33
Dolphin, Andrew E.; Williams, Benjamin F.; Gilbert, Karoline M. +4 more
We have identified 55 candidate high-mass X-ray binaries (HMXBs) in M33 using available archival Hubble Space Telescope (HST) and Chandra imaging to find blue stars associated with X-ray positions. We use the HST photometric data to model the colour-magnitude diagrams in the vicinity of each candidate HMXB to measure a resolved recent star formati…
Characterizing the circum-galactic medium of damped Lyman-α absorbing galaxies
Pieri, Matthew; York, Donald G.; Péroux, Céline +8 more
Gas flows in and out of galaxies through their circum-galactic medium (CGM) are poorly constrained and direct observations of this faint, diffuse medium remain challenging. We use a sample of five z ∼ 1-2 galaxy counterparts to damped Lyman-α absorbers (DLAs) to combine data on cold gas, metals and stellar content of the same galaxies. We present …
Multiband counterparts of two eclipsing ultraluminous X-ray sources in M 51
Motch, C.; Miller-Jones, J. C. A.; Soria, R. +5 more
We present the discovery and interpretation of ionized nebulae around two ultraluminous X-ray sources in M 51; both sources share the rare property of showing X-ray eclipses by their companion stars and are therefore prime targets for follow-up studies. Using archival Hubble Space Telescope images, we found an elongated, 100-pc-long emission-line …
Galactic binaries can explain the Fermi Galactic centre excess and 511 keV emission
Calore, F.; Bartels, R.; Storm, E. +1 more
The Fermi-LAT Galactic Centre excess and the 511 keV positron-annihilation signal from the inner Galaxy bear a striking morphological similarity. We propose that both can be explained through a scenario in which millisecond pulsars produce the Galactic Centre excess and their progenitors, low-mass X-ray binaries, the 511 keV signal. As a proof of …
A predicted astrometric microlensing event by a nearby white dwarf
McGill, Peter; Smith, Leigh C.; Belokurov, Vasily +2 more
We used the Tycho-Gaia Astrometric Solution catalogue, part of Gaia Data Release 1, to search for candidate astrometric microlensing events expected to occur within the remaining lifetime of the Gaia satellite. Our search yielded one promising candidate. We predict that the nearby DQ type white dwarf LAWD 37 (WD 1142-645) will lens a background st…
Understanding the strong intervening O VI absorber at zabs ∼ 0.93 towards PG1206+459
Wakker, B. P.; Kacprzak, G. G.; Muzahid, S. +3 more
We have obtained new observations of the partial Lyman limit absorber at zabs=0.93 towards quasar PG 1206+459, and revisit its chemical and physical conditions. The absorber, with N({H I})∼ 10^{17.0} cm-2 and absorption lines spread over ≳1000 km s-1 in velocity, is one of the strongest known O VI absorbers at \log…
X-ray reflection from the inner disc of the AGN Ton S180
Fabian, A. C.; Miller, J. M.; Parker, M. L.
We analyse a long archival XMM-Newton observation of the narrow-line Seyfert 1 galaxy Ton S180, using the latest reflection models to explore the high quality X-ray spectrum. We find that the iron line is relatively narrow and sharp, and the soft excess is extremely smooth. We cannot find an acceptable reflection model that describes both componen…
Summer outbursts in the coma of comet 67P/Churyumov-Gerasimenko as observed by Rosetta-VIRTIS
D'Aversa, E.; Kappel, D.; Erard, S. +20 more
We present an analysis of transient events observed by the Visible InfraRed Thermal Imaging Spectrometer, instrument aboard Rosetta, for the dates of 2015 August 10, September 13 and 14, during the two months surrounding the comet perihelion passage of the Rosetta spacecraft. We detected and characterized events with life-times ranging from 26 min…