Search Publications
Photometric redshifts with the quasi Newton algorithm (MLPQNA) Results in the PHAT1 contest
Brescia, M.; Cavuoti, S.; Mercurio, A. +1 more
Context. Since the advent of modern multiband digital sky surveys, photometric redshifts (photo-z's) have become relevant if not crucial to many fields of observational cosmology, such as the characterization of cosmic structures and the weak and strong lensing.
Aims: We describe an application to an astrophysical context, namely the evaluati…
A new technique to efficiently select Compton-thick AGN
Caccianiga, A.; Severgnini, P.; Della Ceca, R.
Aims: We present a new efficient diagnostic method, based on mid-infrared and X-ray data, to select local (z < 0.1) Compton-thick AGN with the aim of estimating their surface and space density.
Methods: We define a region in the X-ray-to-mid-IR [F(2-12 keV)/F25ν25] vs. X-ray color (HR) plane associated to Compton…
Spectral monitoring of RX J1856.5-3754 with XMM-Newton. Analysis of EPIC-pn data
Haberl, F.; Tiengo, A.; Mereghetti, S. +3 more
Using a large set of XMM-Newton observations, we searched for the long-term spectral and flux variability of the isolated neutron star RX J1856.5-3754 in the time interval from April 2002 to October 2011. This is the brightest and most extensively observed source of a small group of nearby, thermally emitting isolated neutron stars, of which at le…
Unusual quasars from the Sloan Digital Sky Survey selected by means of Kohonen self-organising maps
Meusinger, H.; Scholz, R. -D.; de Hoon, A. +4 more
Context. Large spectroscopic surveys have discovered very peculiar and hitherto unknown types of active galactic nuclei (AGN). Such rare objects may hold clues to the accretion history of the supermassive black holes at the centres of galaxies.
Aims: We aim to create a sizeable sample of unusual quasars from the unprecedented spectroscopic da…
Fe K emission from active galaxies in the COSMOS field
Sanders, D. B.; Taniguchi, Y.; Salvato, M. +14 more
We present a rest-frame spectral stacking analysis of ~1000 X-ray sources detected in the XMM-COSMOS field to investigate the iron-K line properties of active galaxies beyond redshift z ~ 1. In Type I AGN that have a typical X-ray luminosity of LX ~ 1.5 × 1044 (erg s-1) and z ~ 1.6 the cold Fe K at 6.4 keV is weak …
AKARI near-infrared spectroscopy of the aromatic and aliphatic hydrocarbon emission features in the galactic superwind of M 82
Onaka, T.; Kaneda, H.; Minh, Y. C. +4 more
Aims: We investigate the properties of hydrocarbon grains in the galactic superwind of M 82.
Methods: With AKARI, we performed near-infrared (2.5-4.5 µm) spectroscopic observations of 34 regions in M 82 including its northern and southern halos.
Results: Many of the spectra show strong emission at 3.3 µm caused by polycy…
I Zw 18 as morphological paradigm for rapidly assembling high-z galaxies
Östlin, G.; Papaderos, P.
Context.
"TNOs are Cool": A survey of the trans-Neptunian region. VII. Size and surface characteristics of (90377) Sedna and 2010 EK139
Hartogh, P.; Pál, A.; Lellouch, E. +14 more
We present estimates of the basic physical properties (size and albedo) of (90377) Sedna, a prominent member of the detached trans-Neptunian object population and the recently discovered scattered disk object 2010 EK139, based on the recent observations acquired with the Herschel Space Observatory, within the "TNOs are Cool!" key progra…
Multiwavelength campaign on Mrk 509. X. Lower limit on the distance of the absorber from HST COS and STIS spectroscopy
Kaastra, J. S.; Kriss, G. A.; Arav, N. +15 more
Aims: Active galactic nuclei (AGN) often show evidence of photoionized outflows. A major uncertainty in models for these outflows is the distance (R) to the gas from the central black hole. In this paper we use the HST/COS data from a massive multi-wavelength monitoring campaign on the bright Seyfert I galaxy Mrk 509, in combination with arch…
Warm H2O and OH in the disk around the Herbig star HD 163296
Fedele, D.; Henning, Th.; van Dishoeck, E. F. +5 more
We present observations of far-infrared (50-200 µm) OH and H2O emission of the disk around the Herbig Ae star HD 163296 obtained with Herschel/PACS in the context of the DIGIT key program. In addition to strong [O i] emission, a number of OH doublets and a few weak highly excited lines of H2O are detected. The presence …