ArcAdiA

A broad-line region origin for the iron Kα line in NGC 7213

2011-12-22T13:35:28Z

A broad-line region origin for the iron Kα line in NGC 7213 Bianchi, Stefano; La Franca, Fabio; Matt, Giorgio; Guainazzi, Matteo; Jimenez Bailon, Elena; Longinotti, Anna Lia; Nicastro, Fabrizio; Pentericci, Laura 2008-07 Monthly Notices of the Royal Astronomical Society: Letters 389 52-56 The X-ray spectrum of NGC 7213 is known to present no evidence for Compton reflection, a unique result among bright Seyfert 1s. The observed neutral iron Kα line, therefore, cannot be associated with a Compton-thick material, like the disc or the torus, but is due to Compton-thin gas, with the broad-line region (BLR) as the most likely candidate. To check this hypothesis, a long Chandra High-Energy Transmission Grating observation, together with a quasi-simultaneous optical spectroscopic observation at the ESO NTT EMMI were performed. We found that the iron line is resolved with a full width at half-maximum (FWHM) = 2400+1100-600kms-1, in perfect agreement with the value measured for the broad component of the Hα, 2640+110-90kms-1. Therefore, NGC 7213 is the only Seyfert 1 galaxy whose iron Kα line is unambiguously produced in the BLR. We also confirmed the presence of two ionized iron lines and studied them in greater detail than before. The resonant line is the dominant component in the Fe XXV triplet, therefore suggesting an origin in collisionally ionized gas. If this is the case, the blueshift of around 1000kms-1 of the two ionized iron lines could be the first measure of the velocity of a starburst wind from its X-ray emission.

The XMM-Newton long look of NGC 1365: uncovering of the obscured X-raysource

2011-12-22T13:34:34Z

The XMM-Newton long look of NGC 1365: uncovering of the obscured X-raysource Risaliti, Guido; Salvati, Marco; Elvis, Martin; Fabbiano, Giuseppina; Baldi, Alessandro; Bianchi, Stefano; Braito, Valentina; Guainazzi, Matteo; Matt, Giorgio; Miniutti, Giovanni; Reeves, James; Soria, Roberto; Zezas, Andreas 2009 Monthly notices of the royal astronomical society 393 L1 We present an analysis of the extreme obscuration variability observedduring an XMM-Newton 5-d continuous monitoring of the active galacticnuclei (AGN) in NGC 1365. The source was in a reflection-dominatedstate in the first similar to 1.5 d, then a strong increase in the 7-10keV emission was observed in similar to 10 h, followed by a symmetricdecrease. The spectral analysis of the different states clearly showsthat this variation is due to an uncovering of the X-ray source. Fromthis observation, we estimate a size of the X-ray source D-S < 10(13)cm, a distance of the obscuring clouds R similar to 10(16) cm and adensity n similar to 10(11) cm(-3). These values suggest that the X-rayabsorption/reflection originates from the broad-line region clouds.This is also supported by the resolved width of the iron narrow K alphaemission line, consistent with the width of the broad H beta line.

CAIXA: a catalogue of AGN in the XMM-Newton archive II. Multiwavelength correlations

2011-12-22T13:34:34Z

CAIXA: a catalogue of AGN in the XMM-Newton archive II. Multiwavelength correlations Bianchi, Stefano; Bonilla, N. Fonseca; Guainazzi, Matteo; Matt, Giorgio; Ponti, Gabriele 2009 Astronomy & Astrophysics 501 915-924 Aims. The availability of large amounts of multiwavelength data allows us to perform an extensive statistical analysis to look for correlations between different parameters of AGN. The physical implications of these correlations, when considered within the framework of current AGN models, can be enlightening in the resolution of the problems and the open issues which still characterise this class of sources. Methods. We presented CAIXA, a Catalogue of AGN in the XMM-Newton Archive, in a companion paper. It consists of radio-quiet X-ray unobscured sources, which cover a range in X-ray luminosities between L2-10keV = 2.0 x 10(41) and 3.9 x 10(46) erg s(-1), and in redshift from z = 0.002 to z = 4.520. Here, a systematic search for correlations between the X-ray spectral properties and the multiwavelength data was performed for the sources in CAIXA. All the significant (>99.9%confidence level) correlations are discussed along with their physical implications for current models of AGN. Results. Two main correlations are discussed in this paper: a) a very strong anti-correlation between the FWHM of the H beta optical line and the ratio between the soft and the hard X-ray luminosity. Although similar anti-correlations between optical line width and X-ray spectral steepness have already been discussed in the literature, we consider the formulation we present in this paper as more fundamental, as it links model-independent quantities. Coupled with a strong anti-correlation between the V to hard X-ray flux ratio and the H betaFHWM, it supports scenarios for the origin of the soft excess in AGN, which require strong suppression of the hard X-ray emission; b) a strong (and expected) correlation between the X-ray luminosity and the black hole mass. Its slope, flatter than 1, is consistent with Eddington ratio-dependent bolometric corrections. Moreover, we critically review through various statistical tests the role that distance biases play in the strong radio to X-ray luminosity correlation found in CAIXA and elsewhere; we conclude that only complete, unbiased samples should be used to draw observational constraints on the origin of radio emission in radio-quiet AGN.

CAIXA: a catalogue of AGN in the XMM-Newton archive I. Spectral analysis

2011-12-22T13:35:28Z

CAIXA: a catalogue of AGN in the XMM-Newton archive I. Spectral analysis Bianchi, Stefano; Guainazzi, Matteo; Matt, Giorgio; Bonilla, N. Fonseca; Ponti, Gabriele 2009-02 Astronomy & Astrophysics 495 421-430 Aims. We present CAIXA, a Catalogue of AGN In the XMM-Newton Archive.It consists of all the radio-quiet X-ray unobscured (N-H < 2 x 10(22)cm(-2)) active galactic nuclei (AGN) observed by XMM-Newton in targetedobservations, whose data are public as of March 2007. With its 156sources, this is the largest catalogue of high signal-to-noise X-rayspectra of AGN.Methods. All the EPIC pn spectra of the sources in CAIXA were extractedhomogeneously, and a baseline model was applied in order to derivetheir basic X-ray properties. These data are complemented bymultiwavelength data found in the literature: black hole masses, fullwidth half maximum (FWHM) of H beta, radio and optical fluxes.Results. Here we describe our homogeneous spectral analysis of theX-ray data in CAIXA and present all the results on the parametersadopted in our best-fit models.

Suzaku observation of the Phoenix galaxy

2011-12-22T13:35:28Z

Suzaku observation of the Phoenix galaxy Matt, Giorgio; Bianchi, Stefano; Awaki, Hisamitsu; Comastri, Andrea; Guainazzi, Matteo; Iwasawa, Kazushi; Jimenez-Bailon, Elena; Nicastro, Fabrizio 2009-03 Astronomy & Astrophysics 496 653-658 Context. In recent years, several Seyfert 2 galaxies have beendiscovered that change state when observed in X-rays a few years apart,switching from Compton-thin to reflection-dominated or viceversa.Aims. We observed a member of this class of "Changing-look" sources,the Phoenix galaxy, with Suzaku, with the aim of better understandingthe nature of the variations.Methods. The Suzaku spectrum was analyzed, and the results comparedwith previous ASCA and XMM-Newton observations.Results. The source was caught in a Compton-thin state, as inXMM-Newton, but differently from ASCA. Comparing the Suzaku andXMM-Newton observations, a variation in the column density of theabsorber on a time scale of years is discovered. A similar change, buton much shorter time scales (i.e. ks) may also explain the count-ratevariations during the Suzaku observations. A soft excess is alsopresent, likely due to continuum and line emission from photoionizedcircumnuclear matter.