DISCOVERY OF STRONG IRON Kα EMITTING COMPTON THICK QUASARS AT
                    <i>z</i>
                    = 2.5 AND 2.9

Feruglio, C.; Daddi, E.; Fiore, F.; Alexander, D. M.; Piconcelli, E.; Malacaria, C.

doi:10.1088/2041-8205/729/1/l4

Cited by 51 publications

(72 citation statements)

References 50 publications

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“…More quantitatively, the absorbed X-ray selected QSOs exhibit luminosity ratios in the range 0.3 L FIR /L AGN 5 (Stevens et al 2005;Vignali et al 2009;Gilli et al 2011;Feruglio et al 2011), supporting the view that they typically reach their large X-ray luminosity when star formation is still vigorous.…”

Section: Star Formation In High Redshift X-ray Selected Agns and Qsosmentioning

confidence: 60%

The Coevolution of Supermassive Black Holes and Massive Galaxies at High Redshift

Lapi

Raimundo

Aversa

et al. 2014

ApJ

114

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We exploit the recent, wide samples of far-infrared (FIR) selected galaxies followed-up in X rays and of X-ray/optically selected active galactic nuclei (AGNs) followed-up in the FIR band, along with the classic data on AGN and stellar luminosity functions at high redshift z 1.5, to probe different stages in the coevolution of supermassive black holes (BHs) and host galaxies. The results of our analysis indicate the following scenario: (i) the star formation in the host galaxy proceeds within a heavily dust-enshrouded medium at an almost constant rate over a timescale 0.5 − 1 Gyr, and then abruptly declines due to quasar feedback; over the same timescale, (ii) part of the interstellar medium loses angular momentum, reaches the circum-nuclear regions at a rate proportional to the star formation and is temporarily stored into a massive reservoir/proto-torus wherefrom it can be promptly accreted; (iii) the BH grows by accretion in a self-regulated regime with radiative power that can slightly exceed the Eddington limit L/L Edd 4, particularly at the highest redshifts; (iv) for massive BHs the ensuing energy feedback at its maximum exceeds the stellar one and removes the interstellar gas, thus stopping the star formation and the fueling of the reservoir; (v) afterwards, if the latter has retained enough gas, a phase of supply-limited accretion follows exponentially declining with a timescale of about 2 e-folding times. We also discuss how the detailed properties and the specific evolution of the reservoir can be investigated via coordinated, high-resolution observations of starforming, strongly-lensed galaxies in the (sub-)mm band with ALMA and in the X-ray band with Chandra and the next generation X-ray instruments.

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Section: Star Formation In High Redshift X-ray Selected Agns and Qsosmentioning

confidence: 60%

The Coevolution of Supermassive Black Holes and Massive Galaxies at High Redshift

Lapi

Raimundo

Aversa

et al. 2014

ApJ

114

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“…In the low S/N regime, it is hard to determine whether a highly obscured source is Compton-thick or -thin (see also the comparison of Compton-thick AGN identification results from different works by Castelló-Mor et al 2013). We note that some Comptonthick candidates identified by previous spectral analyses are classified as Compton-thin in this work, including sources 375 (Feruglio et al 2011, named BzK8608 therein), 551 (Comastri et al 2011, CXOCDFSJ033229.8-275106), 328 (Norman et al 2002;Comastri et al 2011, CXOCDFSJ033218.3-275055), 419 (Del Moro et al 2016, ID=23), 240 (Georgantopoulos et al 2013, XID=191), and 867 (Georgantopoulos et al 2013, XID=634). According to our spectral analysis, these sources are found to be Compton-thin but still highly obscured, with N H between 5.5 10 23 -1.1 10 24 cm −2 .…”

Section: Distribution Of N H Excluding Compton-thick Sourcesmentioning

confidence: 65%

X-Ray Spectral Analyses of AGNs from the 7Ms Chandra Deep Field-South Survey: The Distribution, Variability, and Evolutions of AGN Obscuration

Liu

Tozzi²,

Wang

et al. 2017

ApJS

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We present a detailed spectral analysis of the brightest active galactic nuclei (AGNs) identified in the 7Ms Chandra Deep Field-South (CDF-S) survey over a time span of 16 years. Using a model of an intrinsically absorbed power-law plus reflection, with possible soft excess and narrow Fe Kα line, we perform a systematic X-ray spectral analysis, both on the total 7Ms exposure and in four different periods with lengths of 2–21 months. With this approach, we not only present the power-law slopes, column densities , observed fluxes, and absorption-corrected 2–10 keV luminosities L X for our sample of AGNs, but also identify significant spectral variabilities among them on timescales of years. We find that the variabilities can be ascribed to two different types of mechanisms, either flux-driven or flux-independent. We also find that the correlation between the narrow Fe line EW and can be well explained by the continuum suppression with increasing . Accounting for the sample incompleteness and bias, we measure the intrinsic distribution of for the CDF-S AGN population and present reselected subsamples that are complete with respect to . The -complete subsamples enable us to decouple the dependences of on L X and on redshift. Combining our data with those from C-COSMOS, we confirm the anticorrelation between the average and L X of AGN, and find a significant increase of the AGN-obscured fraction with redshift at any luminosity. The obscured fraction can be described as .

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“…There are various reports in the literature on Compton thick AGN candidates in the CDFS using whole or part of the Chandra 4 Ms data (e.g., Norman et al 2002;Mainieri et al 2005;Tozzi et al 2006;Fiore et al 2008;Gilli et al 2011;Feruglio et al 2011;Luo et al 2011;Brightman & Ueda 2012;Fiore et al 2012). Some of them lie in the redshift range of our sample, although they are expectedly faint and just a few of them entered in our sample of relatively bright sources.…”

Section: X-ray Selection Of Heavily Obscured Agnmentioning

confidence: 90%

The XMM deep survey in the CDF-S

Iwasawa

Gilli

Vignali

et al. 2012

A&A

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We present results on a search of heavily obscured active galaxies z > 1.7 using the rest-frame 9−20 keV excess for X-ray sources detected in the deep XMM-CDFS survey. Out of 176 sources selected with the conservative detection criteria (>8σ) in the first source catalogue of Ranalli et al. (in prep.), 46 objects lie in the redshift range of interest with the median redshiftz 2.5. Their typical rest-frame 10−20 keV luminosity is 10 44 erg s −1 , as observed. Among optically faint objects that lack spectroscopic redshift, four were found to be strongly absorbed X-ray sources, and the enhanced Fe K emission or absorption features in their X-ray spectra were used to obtain X-ray spectroscopic redshifts. Using the X-ray colour-colour diagram based on the rest-frame 3−5 keV, 5−9 keV, and 9−20 keV bands, seven objects were selected for their 9−20 keV excess and were found to be strongly absorbed X-ray sources with column density of N H ≥ 0.6 × 10 24 cm −2 , including two possible Compton thick sources. While they are emitting at quasar luminosity, ∼3/4 of the sample objects are found to be absorbed by N H > 10 22 cm −2 . A comparison with local AGN at the matched luminosity suggests an increasing trend of the absorbed source fraction for high-luminosity AGN towards high redshifts.

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DISCOVERY OF STRONG IRON Kα EMITTING COMPTON THICK QUASARS AT z = 2.5 AND 2.9

Cited by 51 publications

References 50 publications

The Coevolution of Supermassive Black Holes and Massive Galaxies at High Redshift

The Coevolution of Supermassive Black Holes and Massive Galaxies at High Redshift

X-Ray Spectral Analyses of AGNs from the 7Ms Chandra Deep Field-South Survey: The Distribution, Variability, and Evolutions of AGN Obscuration

The XMM deep survey in the CDF-S

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