Search Publications
Multifractal analysis of the interstellar medium: first application to Hi-GAL observations
Hennebelle, Patrick; Elia, Davide; Molinari, Sergio +6 more
The multifractal geometry remains an underexploited approach to describe and quantify the large-scale structure of interstellar clouds. In this paper, the typical tools of multifractal analysis are applied to Herschel far-infrared (70-500µ m) dust continuum maps, which represent an ideal case of study. This dust component is a relatively opt…
Mystery solved: discovery of extended radio emission in the merging galaxy cluster Abell 2146
Fabian, A. C.; Hlavacek-Larrondo, J.; van Weeren, R. J. +11 more
Abell 2146 (z = 0.232) is a massive galaxy cluster currently undergoing a spectacular merger in the plane of the sky with a bullet-like morphology. It was the first system in which both the bow and upstream shock fronts were detected at X-ray wavelengths (Mach ∼2), yet deep Giant MetreWave Telescope 325 MHz observations failed to detect extended r…
A new ultraluminous X-ray source in the galaxy NGC 5907
Salvaterra, R.; Tiengo, A.; Israel, G. +14 more
We report on the serendipitous discovery of a new transient in NGC 5907, at a peak luminosity of 6.4 × 1039 erg s-1. The source was undetected in previous 2012 Chandra observations with a 3σ upper limit on the luminosity of 1.5 × 1038 erg s-1, implying a flux increase of a factor of >35. We analysed t…
The 155-day X-ray cycle of the very massive Wolf-Rayet star Melnick 34 in the Large Magellanic Cloud
Crowther, P. A.; Pollock, A. M. T.; Townsley, Leisa K. +2 more
The Wolf-Rayet star Mk 34 was observed more than 50 times as part of the deep T-ReX Chandra ACIS-I X-ray imaging survey of the Tarantula Nebula in the Large Magellanic Cloud conducted between 2014 May and 2016 January. Its brightness showed one bright maximum and repeated faint minima which help define an X-ray recurrence time of 155.1 ± 0.1 d tha…
A high-velocity component to the complex absorption in IRAS 13349+2438
Guainazzi, M.; Schartel, N.; Santos-Lleó, M. +4 more
We present an analysis of XMM-Newton spectra of the low-redshift quasar IRAS 13349+2438. The Reflection Grating Spectrometer spectrum shows a large number of absorption lines from two zones of warm absorption, with velocities of ∼-600 km s-1, as noted by previous authors. Additionally, we find robust evidence from multiple Lyα absorptio…
Extending Gaia DR2 with HST narrow-field astrometry: the WISE J154151.65-225024.9 test case
Bedin, L. R.; Fontanive, C.
One field containing WISE J154151.65- 225024.9 was observed by Hubble Space Telescope at three different epochs taken in ∼5 yr. We measured positions of sources in all images and successfully linked these positions to the Gaia DR2 absolute system to derive the astrometric parameters for this faint close-by Y1 brown dwarf. The developed procedure a…
NuSTAR observations of Mrk 766: distinguishing reflection from absorption
Harrison, F. A.; Stern, D.; Zhang, W. W. +15 more
We present two new NuSTAR observations of the narrow-line Seyfert 1 (NLS1) galaxy Mrk 766 and give constraints on the two scenarios previously proposed to explain its spectrum and that of other NLS1s: relativistic reflection and partial covering. The NuSTAR spectra show a strong hard (>15 keV) X-ray excess, while simultaneous soft X-ray coverag…
On the identification of wide binaries in the Kepler field
Godoy-Rivera, Diego; Chanamé, Julio
We perform a search for wide binaries in the Kepler field with the prospect of providing new constraints for gyrochronology. First, we construct our base catalogue by compiling astrometry for the stars observed by Kepler, and supplement it with parallaxes, radial velocities (RVs), and metallicities. We then mine our base catalogue for wide binary …
CCD photometry, Roche modelling and period analysis of the W UMa eclipsing binary star system AR CrB
Nelson, Robert H.; Alton, Kevin B.
AR CrB (GSC 2040-1361) is a W UMa-type binary system (P = 0.397351 d) which has been poorly studied since first detected over 17 yr ago; only a single unfiltered light curve (LC) has been published. Photometric data collected in three bandpasses (B, V, and Rc) at UnderOak Observatory produced four new times-of-minimum for AR CrB. These …
STREAMFINDER II: A possible fanning structure parallel to the GD-1 stream in Pan-STARRS1
Goldman, Bertrand; Magnier, Eugene; Malhan, Khyati +3 more
STREAMFINDER is a new algorithm that we have built to detect stellar streams in an automated and systematic way in astrophysical datasets that possess any combination of positional and kinematic information. In Paper I, we introduced the methodology and the workings of our algorithm and showed that it is capable of detecting ultra-faint and distan…