http://dspace-roma3.caspur.it:80 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Tue, 21 May 2013 07:42:06 GMT 2013-05-21T07:42:06Z http://dspace-roma3.caspur.it/image/logo_roma3.jpg http://dspace-roma3.caspur.it:80 http://hdl.handle.net/2307/273 <Title>A broad-line region origin for the iron Kα line in NGC 7213</Title> <Authors>Bianchi, Stefano; La Franca, Fabio; Matt, Giorgio; Guainazzi, Matteo; Jimenez Bailon, Elena; Longinotti, Anna Lia; Nicastro, Fabrizio; Pentericci, Laura</Authors> <Issue Date>2008-07</Issue Date> <Is part of>Monthly Notices of the Royal Astronomical Society: Letters</Is part of> <Volume>389</Volume> <Pages>52-56</Pages> <Abstract>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.</Abstract> Mon, 30 Jun 2008 22:00:00 GMT http://hdl.handle.net/2307/273 2008-06-30T22:00:00Z http://hdl.handle.net/2307/286 <Title>Suzaku observation of the Phoenix galaxy</Title> <Authors>Matt, Giorgio; Bianchi, Stefano; Awaki, Hisamitsu; Comastri, Andrea; Guainazzi, Matteo; Iwasawa, Kazushi; Jimenez-Bailon, Elena; Nicastro, Fabrizio</Authors> <Issue Date>2009-03</Issue Date> <Is part of>Astronomy & Astrophysics</Is part of> <Volume>496</Volume> <Pages>653-658</Pages> <Abstract>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.</Abstract> Sat, 28 Feb 2009 23:00:00 GMT http://hdl.handle.net/2307/286 2009-02-28T23:00:00Z