The size of the X-ray emitting region in SWIFT J2127.4+5654 via a broad line region cloud X-ray eclipse

Abstract

We present results obtained from the time-resolved X-ray spectral analysis of the Narrow-Line-Seyfert 1 galaxy SWIFT J2127.4+5654 during a ∼ 130 ks XMM-Newton observation. We reveal large spectral variations, especially during the first ∼ 90 ks of the XMM-Newton exposure. The spectral variability can be attributed to a partial eclipse of the X-ray source by an intervening low-ionization/cold absorbing structure (cloud) with column density N H = 2.0 +0.2 −0.3 ×10 22 cm −2 which gradually covers and then uncovers the X-ray emitting region with covering fraction ranging from zero to ∼ 43 per cent. Our analysis enables us to constrain the size, number density, and location of the absorbing cloud with good accuracy. We infer a cloud size (diameter) of D c 1.5 × 10 13 cm, corresponding to a density of n c 1.5 × 10 9 cm −3 at a distance of R c 4.3 × 10 16 cm from the central black hole. All of the inferred quantities concur to identify the absorbing structure with one single cloud associated with the broad line region of SWIFT J2127.4+5654. We are also able to constrain the X-ray emitting region size (diameter) to be D s 2.3 × 10 13 cm which, assuming the black hole mass estimated from single-epoch optical spectroscopy (1.5 × 10 7 M ⊙ ), translates into D s 10.5 gravitational radii (r g ) with larger sizes (in r g ) being associated with smaller black hole masses, and viceversa. We also confirm the presence of a relativistically distorted reflection component off the inner accretion disc giving rise to a broad relatvistic Fe K emission line and small soft excess (small because of the high Galactic column density), supporting the measurement of an intermediate black hole spin in SWIFT J2127.4+5654 that was obtained from a previous Suzaku observation.

Properties of AGN coronae in theNuSTARera

“…Together, the evidence points to the corona being compact (Fabian 2012;Reis & Miller 2013). Further evidence of a small physical size of the corona emerges from observations of the emissivity profile of the broad iron line (Wilkins & Fabian 2011) and from varying obscuration of the corona by clouds (Risaliti et al 2011;Sanfrutos et al 2013).…”

Anatomy of the AGN in NGC 5548

“…Despite being recorded here for the first time in this source, this kind of "obscuration event" may not be unique to NGC 5548. Albeit with less quality data, other fast and variable obscuration events have been recorded in the past in a number of intermediate-type or type 1 sources, such as NGC 3227 (Lamer et al 2003), NGC 1365 (Risaliti et al 2005), NGC 4388 (Elvis et al 2004), NGC 4151 (Puccetti et al 2007), PG1535+547 (Ballo et al 2008), NGC 7582 ), H0557-385 (Longinotti et al 2009;Coffey et al 2014), Mrk 766 (Risaliti et al 2011), SwiftJ2127.4+5654 (Sanfrutos et al 2013), Mrk 335 (Longinotti et al 2013), NGC 5506 (Markowitz et al 2014), NGC 985 (Ebrero et al 2016a,b), Fairall 51 (Svoboda et al 2015), and ESO 323-G77 (Sanfrutos et al 2016), not to mention the systematic surveys by Malizia et al (1997), Markowitz et al (2014), andTorricelli-Ciamponi et al (2015). Based on various arguments, such as the ones above, and including the spectral properties and variability timescales of the absorbers, most authors have associated the origin of the absorbing clouds as either broad line region (BLR) clouds, a clumpy torus, or the inner boundary of a dusty torus.…”

An X-ray variable absorber within the broad line region in Fairall 51

“…However, the absorption variability was later found on a time scale of days in several sources: NGC 4388 (Elvis et al 2004), NGC 1365 (Risaliti et al 2005), NGC 4151 (Puccetti et al 2007), NGC 7582 (Bianchi et al 2009b), PG 1535+547 (Ballo et al 2008), Mrk 766 (Risaliti et al 2011), NGC 5506 , NGC 3227 (Lamer et al 2003;Beuchert et al, in prep. ), or Swift J2127.4+5654 (Sanfrutos et al 2013). The origin of such variability must be significantly closer to the central region.…”