Search Publications
The AGN content in luminous infrared galaxies at z∼ 2 from a global SED analysis including Herschel data
Berta, S.; Magnelli, B.; Nordon, R. +16 more
We use Herschel-PACS far-infrared (IR) data, combined with previous multiband information and mid-IR spectra, to properly account for the presence of an active nucleus and constrain its energetic contribution in luminous IR sources at z∼ 2. The sample is composed of 24 sources in the GOODS-South field, with typical IR luminosity of 1012…
Hubble Space Telescope survey of the Perseus cluster - IV. Compact stellar systems in the Perseus cluster core and ultracompact dwarf formation in star-forming filaments
Conselice, Christopher J.; Penny, Samantha J.; Forbes, Duncan A.
We present the results of the first search for ultracompact dwarfs (UCDs) in the Perseus cluster core, including the region of the cluster around the unusual brightest cluster galaxy NGC 1275. Utilizing Hubble Space Telescope Advanced Camera for Surveys imaging, we identify a sample of 84 UCD candidates with half-light radii 10 < re …
Energy-dependent orbital modulation of X-rays and constraints on emission of the jet in Cyg X-3
Maitra, Chandreyee; Zdziarski, Andrzej A.; Misra, Ranjeev +2 more
We study the orbital modulation of X-rays from Cyg X-3, using data from Swift, INTEGRAL and RXTE. Using the wealth of data presently available and an improved averaging method, we obtain energy-dependent folded and averaged light curves with unprecedented accuracy. We find that above ∼5 keV the modulation depth decreases with increasing energy, wh…
Identifying ultra-cool dwarfs at low Galactic latitudes: a southern candidate catalogue
Marocco, F.; Pinfield, D. J.; Jones, H. R. A. +6 more
We present an ultra-cool dwarf (UCD) catalogue compiled from low southern Galactic latitudes and mid-plane, from a cross-correlation of the Two Micron All-Sky Survey (2MASS) and the SuperCOSMOS survey. The catalogue contains 246 members identified from 5042 deg2 within 220° ≤ ℓ ≤ 360° and 0° < ℓ ≤ 30°, for |b| ≤ 15°. Sixteen candidat…
Polar bulges and polar nuclear discs: the case of NGC 4698
Morelli, L.; Beifiori, A.; Dalla Bontà, E. +5 more
The early-type spiral NGC 4698 is known to host a nuclear disc of gas and stars which is rotating perpendicularly with respect to the galaxy main disc. In addition, the bulge and main disc are characterized by a remarkable geometrical decoupling. Indeed, they appear elongated orthogonally to each other. In this work, the complex structure of the g…
The detection of globular clusters in galaxies as a data mining problem
Paolillo, Maurizio; Puzia, Thomas; Brescia, Massimo +2 more
We present an application of self-adaptive supervised learning classifiers derived from the machine learning paradigm to the identification of candidate globular clusters in deep, wide-field, single-band Hubble Space Telescope (HST) images. Several methods provided by the DAta Mining and Exploration (DAME) web application were tested and compared …
Globular cluster systems of early-type galaxies in low-density environments
Blakeslee, J. P.; Sharples, R. M.; Kundu, A. +4 more
Deep images of 10 early-type galaxies in low-density environments have been obtained with the Advanced Camera for Surveys (ACS) aboard the Hubble Space Telescope. The global properties of the globular cluster (GC) systems of the galaxies have been derived in order to investigate the role of the environment in galaxy formation and evolution. Using …
Detectability of low-energy X-ray spectral components in type 1 active galactic nuclei
Mateos, S.; Stewart, G. C.; Scott, A. E.
In this paper we examine the percentage of type 1 active galactic nuclei (AGN) which require the inclusion of a soft excess component and/or significant cold absorption in the modelling of their X-ray spectra obtained by XMM-Newton. We do this by simulating spectra which mimic typical spectral shapes in order to find the maximum detectability expe…
Fast X-ray transients towards the Galactic bulge with the Rossi X-ray Timing Explorer
Negueruela, I.; Swank, J. H.; Markwardt, C. B. +1 more
In X-ray binaries, rapid variability in X-ray flux of greater than an order of magnitude on time-scales of a day or less appears to be a signature of wind accretion from a supergiant companion. When the variability takes the form of rare, brief, bright outbursts with only faint emission between them, the systems are called supergiant fast X-ray tr…
A superburst candidate in EXO 1745-248 as a challenge to thermonuclear ignition models
Altamirano, D.; Degenaar, N.; Wijnands, R. +6 more
We report on Chandra, Rossi X-ray Timing Explorer (RXTE), Swift/Burst Alert Telescope (BAT) and MAXI observations of an X-ray flare of ∼1 d and subsequent outburst of a transient X-ray source observed in 2011 October-November in the globular cluster Terzan 5. We show that the source is the same as the transient that was active in 2000, i.e. the ne…