English
Related papers

Related papers: 2.5-12 micron spectrophotometry and imaging of the…

200 papers

We present 2.5-11 micron spectrophotometric & imaging ISO observations of 28 Sf1, 29 Sf2 & 1 normal galaxy. The Sf1 & Sf2 MIR spectra are statistically different: Sf1 have a strong power-law continuum of index -0.84+/-0.24 & weak PAH…

Astrophysics · Physics 2007-05-23 J. Clavel , B. Schulz , B. Altieri , P. Barr , P. Claes , A. Heras , K. Leech , L. Metcalfe , A. Salama

We present an analysis of the X-ray properties of sources detected in the 13H XMM-Newton deep (200ks) field. In order to constrain the absorbed AGN population, we use extensive Monte Carlo simulations to directly compare the X-ray colours…

Astrophysics · Physics 2009-11-11 T. Dwelly , M. J. Page , N. S. Loaring , K. O. Mason , I. McHardy , K. Gunn , T. Sasseen

In this paper, results of optical identification of ASCA surveys are summarized. To understand luminous AGNs in the z<1 universe, the ASCA AGN sample is still better than samples of AGNs from deep Chandra or XMM-Newton surveys. Combining…

Astrophysics · Physics 2007-05-23 Masayuki Akiyama

Aims. We present a 0.2--200 keV broad-band study of absorbed AGN observed with INTEGRAL, XMM-Newton, Chandra and ASCA to investigate the continuum shape and the absorbing/reflecting medium properties. Methods. The sources are selected in…

Astrophysics · Physics 2009-11-13 A. De Rosa , L. Bassani , P. Ubertini , F. Panessa , A. Malizia , A. J. Dean , R. Walter

We use mid-infrared spectral decomposition to separate the 6micron mid-infrared AGN continuum from the host emission in the ISO low resolution spectra of 71 active galaxies and compare the results to observed and intrinsic 2-10keV hard…

Astrophysics · Physics 2009-11-10 D. Lutz , R. Maiolino , H. W. W. Spoon , A. F. M. Moorwood

We present new photometry of 16 local Seyferts including 6 Compton-thick sources in N-band filters around 12-microns, obtained with the VISIR instrument on the 8-m Very Large Telescope. The near-diffraction-limited imaging provides the…

Astrophysics of Galaxies · Physics 2015-05-13 P. Gandhi , H. Horst , A. Smette , S. Hoenig , A. Comastri , R. Gilli , C. Vignali , W. Duschl

We present a multi-waveband analysis of a 126 galaxy sub-sample of the 12 micron galaxy sample (12MGS), for which we have carried out a detailed X-ray spectral analysis of in a previous paper. We present optical activity classes and we…

High Energy Astrophysical Phenomena · Physics 2015-05-27 Murray Brightman , Kirpal Nandra

We present an X-ray spectral analysis of 126 galaxies of the 12 micron galaxy sample. We pay particular attention to Compton thick AGN with the help of new spectral fitting models that we have produced, which are based on Monte-Carlo…

High Energy Astrophysical Phenomena · Physics 2015-05-20 Murray Brightman , Kirpal Nandra

Several authors have claimed that the less luminous active galactic nuclei (AGN) are not capable of sustaining the dusty torus structure. Thus, a gradual re-sizing of the torus is expected when the AGN luminosity decreases. Our aim is to…

We present an atlas of mid-infrared (mid-IR) ~7.5-13micron spectra of 45 local active galactic nuclei (AGN) obtained with CanariCam on the 10.4m Gran Telescopio CANARIAS (GTC) as part of an ESO/GTC large program. The sample includes…

Aims. High angular resolution N-band imaging is used to discern the torus of active galactic nuclei (AGN) from its environment in order to allow a comparison of its mid-infrared properties to the expectations of the unified scenario for…

Astrophysics of Galaxies · Physics 2009-11-13 Hannes Horst , Wolfgang J. Duschl , Poshak Gandhi , Alain Smette

We present the distributions of geometrical covering factors of active galactic nuclei (AGNs) dusty tori (f2) using an X-ray selected complete sample of 227 AGN drawn from the Bright Ultra-hard XMM-Newton Survey. The AGN have z from 0.05 to…

The presence of an obscuring torus at pc-scale distances from the central black hole is the main ingredient for the Unified Model of Active Galactic Nuclei (AGN), as obscured sources are thought to be seen through this structure. However,…

Composite spectra derived from HST observations of moderate redshift (z~1) quasars show that the peak of the spectral energy distribution is at ~1000 A, and that the ionizing continuum falls off smoothly to shorter wavelengths as $f_\nu…

Astrophysics · Physics 2007-05-23 Gerard A. Kriss

We present the analysis of a sample of 35 candidate Compton thick (CT-) active galactic nuclei (AGNs) selected in the nearby Universe (average redshift <z>~0.03) with the Swift-BAT 100-month survey. All sources have available NuSTAR data,…

Context: We investigate mid-infrared and X-ray properties of the dusty torus in unification scenarios for active galactic nuclei. Aims: We use the relation between mid IR and hard X-ray luminosities to constrain AGN unification scenarios.…

Astrophysics · Physics 2009-11-11 Hannes Horst , Alain Smette , Poshak Gandhi , Wolfgang J. Duschl

We study the detectability of the emission associated with the AGN dusty structure at sub-mm wavelengths using ALMA, in a theoretical and observational way. Theoretically, we use the Clumpy models from Nenkova et al. together with the…

We present results of optical identification of the X-ray sources detected in the ASCA Large Sky Survey. Optical spectroscopic observations were done for 34 X-ray sources which were detected with the SIS in the 2-7 keV band above 3.5 sigma.…

According to the unified model, the differences observed in different classes of AGN are due to anisotropic obscuration. This implies that in the hard X-rays, at energies where the radiation can pierce the obscuring material, the average…

Cosmology and Nongalactic Astrophysics · Physics 2011-03-31 C. Ricci , R. Walter , T. J. -L. Courvoisier

We summarize the attempts by our group and others to derive constraints on variations of fundamental constants over cosmic time using quasar absorption lines. Most upper limits reside in the range 0.5-1.5x10-5 at the 3sigma level over a…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Patrick Petitjean , Raghunathan Srianand , Hum Chand , Alexander Ivanchik , Pasquier Noterdaeme , Neeraj Gupta
‹ Prev 1 2 3 10 Next ›