Search Publications
Long-term monitoring of LS I +61°303 with INTEGRAL
Rea, N.; Torres, D. F.; Zhang, S. +3 more
LS I +61°303 is one of the few high-mass X-ray binaries that has been recently observed at TeV and GeV energies. Here we investigate the hard X-ray spectral and timing properties of this source using the IBIS/ISGRI instrument on-board the INTEGRAL satellite. We carry out a systematic analysis based on all available INTEGRAL data since 2002 Decembe…
Early-type galaxies at large galactocentric radii - I. Stellar kinematics and photometric properties
Forbes, Duncan A.; Couch, Warrick J.; Hau, George K. T. +1 more
We present the results of a combined analysis of the kinematic and photometric properties at large galactocentric radii of a sample of 14 low-luminosity early-type galaxies in the Fornax and Virgo clusters. From Gemini South GMOS long-slit spectroscopic data, we measure radial profiles of the kinematic parameters vrot, σ, h3 …
Correlated optical/X-ray variability in the high-mass X-ray binary SAX J2103.5+4545
Zezas, A.; Reig, P.; Słowikowska, A. +1 more
SAX J2103.5+4545 is the Be/X-ray binary (BeX) with the shortest orbital period. It shows extended bright and faint X-ray states that last for a few hundred days. The main objective of this work is to investigate the relationship between the X-ray and optical variability and to characterize the spectral and timing properties of the bright and faint…
Localization of the X-ray source in the globular cluster G1 with Chandra
Barmby, P.; Heinke, C. O.; Cohn, H. N. +5 more
We report the most accurate X-ray position of the X-ray source in the giant globular cluster G1 in M31 by using the Chandra X-ray Observatory, Hubble Space Telescope (HST) and Canada-France-Hawaii Telescope (CFHT). G1 is clearly detected with Chandra and by cross-registering with HST and CFHT images, we derive a 1σ error radius of 0.15arcsec, sign…
The longest observation of a low-intensity state from a supergiant fast X-ray transient: Suzaku observes IGRJ08408-4503
Sidoli, L.; Esposito, P.; Ducci, L.
We report here on the longest deep X-ray observation of a supergiant fast X-ray transient (SFXT) outside outburst, with an average luminosity level of 1033 erg s-1 (assuming 3 kpc distance). This observation was performed with Suzaku in 2009 December and was targeted on IGRJ08408-4503, with a net exposure with the X-ray Imagi…
A blue tilt in the globular cluster system of the Milky Way-like galaxy NGC 5170
Bailin, Jeremy; Spitler, Lee R.; Forbes, Duncan A. +4 more
Here, we present Hubble Space Telescope/Advanced Camera for Surveys (ACS) imaging, in the B and I bands, of the edge-on Sb/Sc galaxy NGC 5170. Excluding the central disc region, we detect 142 objects with colours and sizes typical of globular clusters (GCs). Our main result is the discovery of a `blue tilt' (a mass-metallicity relation), at the 3σ…
Galaxies at a redshift of ~0.5 around three closely spaced quasar sightlines
Bechtold, Jill; Morris, Simon L.; Jannuzi, Buell T. +4 more
We examine the relationship between galaxies and the intergalactic medium at z < 1 using a group of three closely spaced background quasi-stellar objects (QSOs) with zem ~ 1 observed with the Hubble Space Telescope. Using a new grouping algorithm, we identify groups of galaxies and absorbers across the three QSO sightlines that may b…
The nuclear outflow in NGC 2110
Wilson, A. S.; Rosario, D. J.; Nelson, C. H. +1 more
We present a spectroscopic and optical/radio imaging study of the Seyfert NGC 2110 using the Hubble Space Telescope (HST)/Space Telescope Imaging Spectrograph (STIS), aiming to measure the dynamics and understand the nature of the nuclear outflow in the galaxy. Previous HST studies have revealed the presence of a linear structure in the narrow-lin…
The enigmatic young brown dwarf binary FUTau: accretion and activity
Scholz, A.; Micela, G.; Stelzer, B. +1 more
FUTau belongs to a rare class of young, wide brown dwarf binaries. We have resolved the system in a Chandra X-ray observation and detected only the primary, FUTauA. Hard X-ray emission, presumably from a corona, is present but, unexpectedly, we also detect a strong and unusually soft component from FUTauA. Its X-ray properties, so far unique among…
The spectral energy distribution of D-type symbiotic stars: the role of dust shells
Ciroi, S.; Rafanelli, P.; Angeloni, R. +1 more
We have collected continuum data of a sample of D-type symbiotic stars. By modelling their spectral energy distribution in a colliding-wind theoretical scenario we have found characteristics common to all the systems: (1) at least two dust shells are clearly present, one at ~1000K and the other at ~400K they dominate the emission in the infrared; …