Search Publications
Comparing Dark Energy Survey and HST-CLASH observations of the galaxy cluster RXC J2248.7-4431: implications for stellar mass versus dark matter
Benoit-Lévy, A.; D'Andrea, C. B.; Abbott, T. M. C. +66 more
We derive the stellar mass fraction in the galaxy cluster RXC J2248.7-4431 observed with the Dark Energy Survey (DES) during the Science Verification period. We compare the stellar mass results from DES (five filters) with those from the Hubble Space Telescope Cluster Lensing And Supernova Survey (CLASH; 17 filters). When the cluster spectroscopic…
Probing dark energy via galaxy cluster outskirts
Sun, Ming; Morandi, Andrea
We present a Bayesian approach to combine Planck data and the X-ray physical properties of the intracluster medium in the virialization region of a sample of 320 galaxy clusters (0.056 < z < 1.24, kT ≳ 3 keV) observed with Chandra. We exploited the high level of similarity of the emission measure in the cluster outskirts as cosmology proxy. …
A deep Chandra observation of the interacting star-forming galaxy Arp 299
Zezas, A.; Ballo, L.; Della Ceca, R. +1 more
We present results from a 90 ks Chandra ACIS-S observation of the X-ray luminous interacting galaxy system Arp 299 (NGC 3690/IC 694). We detect 25 discrete X-ray sources with luminosities above ∼4.0 × 1038 erg s-1 covering the entire Ultra Luminous X-ray source (ULX) regime. Based on the hard X-ray spectra of the non-nuclear …
The supermassive black hole and double nucleus of the core elliptical NGC 5419
Bender, Ralf; Thomas, Jens; Fabricius, Maximilian H. +5 more
We obtained adaptive-optics assisted SINFONI observations of the central regions of the giant elliptical galaxy NGC 5419 with a spatial resolution of 0.2 arcsec (≈55 pc). NGC 5419 has a large depleted stellar core with a radius of 1.58 arcsec (430 pc). HST and SINFONI images show a point source located at the galaxy's photocentre, which is likely …
X-rays beware: the deepest Chandra catalogue of point sources in M31
Barmby, P.; Vulic, N.; Gallagher, S. C.
This study represents the most sensitive Chandra X-ray point source catalogue of M31. Using 133 publicly available Chandra ACIS-I/S observations totalling ∼1 Ms, we detected 795 X-ray sources in the bulge, north-east, and south-west fields of M31, covering an area of ≈0.6 deg2, to a limiting unabsorbed 0.5-8.0 keV luminosity of ∼10…
The distribution of dark and luminous matter in the unique galaxy cluster merger Abell 2146
McNamara, Brian R.; Fabian, Andrew C.; Santana, Rebecca +9 more
Abell 2146 (z = 0.232) consists of two galaxy clusters undergoing a major merger. The system was discovered in previous work, where two large shock fronts were detected using the Chandra X-ray Observatory, consistent with a merger close to the plane of the sky, caught soon after first core passage. A weak gravitational lensing analysis of the tota…
Geometrical beaming of stellar mass ULXs
Middleton, Matthew J.; King, Andrew
The presence or lack of eclipses in the X-ray light curves of ultraluminous X-ray sources (ULXs) can be directly linked to the accreting system geometry. In the case where the compact object is stellar mass and radiates isotropically, we should expect eclipses by a main-sequence to sub-giant secondary star on the recurrence time-scale of hours to …
Evidence for an evolving cyclotron line energy in 4U 1538-522
Hemphill, Paul B.; Rothschild, Richard E.; Fürst, Felix +6 more
We have performed a full time and luminosity-resolved spectral analysis of the high-mass X-ray binary 4U 1538-522 using the available RXTE, INTEGRAL, and Suzaku data, examining both phase-averaged and pulse-phase-constrained data sets and focusing on the behaviour of the cyclotron resonance scattering feature (CRSF). No statistically significant t…
On the covering fraction variability in an EUV mini-BAL outflow from PG 1206+459
Muzahid, S.; Srianand, R.; Charlton, J. +1 more
We report on the first detection of extreme-ultraviolet (EUV) absorption variability in the Ne VIII λλ770, 780 mini-broad absorption line (mini-BAL) in the spectrum of the quasar (QSO) PG 1206+459. The observed equivalent width (EW) of the Ne VIII doublet shows a ∼4σ variation over a time-scale of 2.8 months in the QSO's rest frame. Both members o…
INTEGRAL study of temporal properties of bright flares in Supergiant Fast X-ray Transients
Sidoli, L.; Postnov, K.; Paizis, A.
We have characterized the typical temporal behaviour of the bright X-ray flares detected from the three Supergiant Fast X-ray Transients (SFXTs) showing the most extreme transient behaviour (XTE J1739-302, IGR J17544-2619, SAX J1818.6-1703). We focus here on the cumulative distributions of the waiting-time (time interval between two consecutive X-…