ChandraandSpitzerUnveil Heavily Obscured Quasars in theChandra/SWIRE Survey

Polletta, M.; Wilkes, B. J.; Siana, Brian; Lonsdale, C. J.; Kilgard, R. E.; Smith, H. E.; Kim, Dongwoo; Owen, F. N.; Efstathiou, A.; Jarrett, T. H.; Stacey, G. J.; Franceschini, A.; Rowan-Robinson, M.; Babbedge, T.; Berta, S.; Fan, Fang; Farrah, D.; González-Solares, E.; Morrison, G.; Surace, J.; Shupe, D. L.

doi:10.1086/500821

Cited by 226 publications

(353 citation statements)

References 118 publications

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“…In the Chandra deep field Tozzi et al (2006) spectroscopically detected 14/280 candidates at 2−10 keV fluxes greater that ∼1.5 × 10 −15 erg cm −2 s −1 . Polletta et al (2006), detected 5/567 X-ray selected candidates in the Chandra SWIRE survey at 2−10 keV fluxes greater than ∼4.6 × 10 −15 erg cm −2 s −1 . In the XMM-COSMOS survey Hasinger et al (2007) selected in the same way as in this paper 18/600 candidates with fluxes greater than ∼3.3 × 10 −15 erg cm −2 s −1 .…”

Section: Discussionmentioning

confidence: 98%

“…In order to obtain the first measurement of the surface density of Compton thick sources, we multiplied the source fraction estimated above in the 2−10 keV band by the cumulative number density predicted by Gilli et al (2007). The resulting log N − log S is shown in the upper panel of (Tozzi et al 2006), the XMM-COSMOS ) and the Chandra-SWIRE survey (Polletta et al 2006). Lower panel: the fraction of Compton thick source candidates in the Lockmann Hole, the CDFS, the XMM-COSMOS and Chandra-SWIRE, respectively from left to right.…”

Section: Discussionmentioning

confidence: 99%

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XMM-Newtonobservations of the Lockman Hole: X-ray source catalogue and number counts

Brunner¹,

Cappelluti²,

Hasinger³

et al. 2007

A&A

130

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Context. The Lockman Hole field represents the sky area of lowest Galactic line-of-sight column density N H = 5.7 × 10 19 cm −2 . It was observed by the XMM-Newton X-ray observatory in 18 pointings for a total of 1.16 Ms (raw EPIC pn observing time) constituting the deepest XMM-Newton exposure so far. After the removal of time intervals with high particle background, the final effective exposure was 637 ks. Aims. We present a catalogue of the X-ray sources detected in the central 0.196 deg 2 of the field and discuss the derived number counts and X-ray colours. Methods. The analysis was performed using the XMM-SAS data analysis package version 6.0. The detection sensitivity and fraction of spurious detections was calibrated using Monte Carlo simulations. Results. In the 0.5−2.0 keV band, a sensitivity limit (defined as the faintest detectable source) of 1.9 × 10 −16 erg cm −2 s −1 was reached. The 2.0−10.0 keV band and 5.0−10.0 keV band sensitivity limits were 9×10 −16 erg cm −2 s −1 and 1.8×10 −15 erg cm −2 s −1 , respectively. A total of 409 sources above a detection likelihood of 10 (3.9 sigma) were found within a radius of 15 off the field centre, of which 340, 266, and 98 sources were detected in the soft, hard, and very hard bands, respectively. The number counts in each energy band are in close agreement with results from previous surveys and with the synthesis models of the X-ray background. Six percent of the Compton-thick source candidates have been selected from the X-ray colour-colour diagram. This fraction is consistent with the most recent predictions of X-ray background population synthesis models at our flux limits. We also estimated, for the first time, the log N − log S relation for Compton-thick AGN.

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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

XMM-Newtonobservations of the Lockman Hole: X-ray source catalogue and number counts

Brunner¹,

Cappelluti²,

Hasinger³

et al. 2007

A&A

130

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“…We initially use six empirical templates from the Spitzer Widearea InfraRed Extragalactic (SWIRE) library of Polletta et al (2006): the SEDs of the starburst galaxies M82 and Arp220, the star-forming QSO Mrk231, and three SEDs derived by combining spectra, models and photometric data which reproduce two type 1 and one type 2 quasars (which therefore also include a contribution in the energy output from star formation). For all 17 sources in our sample, the best SED fit is achieved by using the quasar models, furthermore the FIR photometry does not indicate any excess over the templates.…”

Section: Sed Fitsmentioning

confidence: 99%

“…The only exception is SDSS J233646.20−010732.6, whose IR luminosity is Observed frame optical to sub-mm FeLoBAL SEDs single template best fits. The black line (and also single black points in the near-IR) represents an empirical template from the SWIRE library (Polletta et al 2006). The models are described in Section 3.3.…”

Section: Infrared Luminosities and Star Formation Ratesmentioning

confidence: 99%

A SCUBA-2 survey of FeLoBAL QSOs. Are FeLoBALs in a ‘transition phase’ between ULIRGs and QSOs?

Violino¹,

Coppin²,

Stevens³

et al. 2016

Mon. Not. R. Astron. Soc.

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It is thought that a class of broad absorption line (BAL) QSOs, characterised by Fe absorption features in their UV spectra (called 'FeLoBALs'), could mark a transition stage between the end of an obscured starburst event and a youthful QSO beginning to shed its dust cocoon, where Fe has been injected into the interstellar medium by the starburst. To test this hypothesis we have undertaken deep SCUBA-2 850 µm observations of a sample of 17 FeLoBAL QSOs with 0.89 z 2.78 and -23.31 M B -28.50 to directly detect an excess in the thermal emission of the dust which would probe enhanced star-formation activity. We find that FeLoBALs are not luminous sources in the submillimetre, none of them are individually detected at 850 µm, nor as a population through stacking (F s = 1.14 ± 0.58 mJy). Statistical and survival analyses reveal that FeLoBALs have sub-mm properties consistent with BAL and non-BAL QSOs with matched redshifts and magnitudes. An SED fitting analysis shows that the FIR emission is dominated by AGN activity, and a starburst component is required only in 6/17 sources of our sample; moreover the integrated total luminosity of 16/17 sources is L 10 12 L , high enough to classify FeLoBALs as infrared luminous.In conclusion, we do not find any evidence in support of FeLoBAL QSOs being a transition population between a ULIRG and an unobscured QSO; in particular, FeLoBALs are not characterized by a cold starburst which would support this hypothesis.

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“…Recently Spitzer data have been used to find highly obscured AGNs, both trough mid-infrared color selection (e.g. Stern et al 2005;Polletta et al 2006;Alonso-Herrero et al 2006;Lacy et al 2007) and joint radio-infrared selection (e.g. Donley et al 2005;Weedman et al 2006;Martinez-Sansigre et al 2005.…”

Section: Introductionmentioning

confidence: 99%

AGN counts at 15$\mu{\rm m}$

Franca¹,

Puccetti²,

Sacchi³

et al. 2007

A&A

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Context. The counts of galaxies and AGN in the mid infra-red (MIR) bands are important instruments for studying their cosmological evolution. However, the classic spectral line ratios techniques can become misleading when trying to properly separate AGN from starbursts or even from apparently normal galaxies. Aims. We use X-ray band observations to discriminate AGN activity in previously classified MIR-selected starburst galaxies and to derive updated AGN1 and (Compton thin) AGN2 counts at 15 µm. Methods. XMM observations of the ELAIS-S1 15 µm sample down to flux limits ∼2 × 10 −15 erg cm −2 s −1 (2-10 keV band) were used. We classified as AGN all those MIR sources with a unabsorbed 2-10 keV X-ray luminosity higher that ∼10 42 erg s −1 . Results. We find that at least about 13 ± 6% of the previously classified starburst galaxies harbor an AGN. According to these figures, we provide an updated estimate of the counts of AGN1 and (Compton thin) AGN2 at 15 µm. It turns out that at least 24% of the extragalactic sources brighter than 0.6 my at 15 µm are AGN (∼13% contribution to the extragalactic background produced at fluxes brighter than 0.6 mJy).

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ChandraandSpitzerUnveil Heavily Obscured Quasars in theChandra/SWIRE Survey

Cited by 226 publications

References 118 publications

XMM-Newtonobservations of the Lockman Hole: X-ray source catalogue and number counts

XMM-Newtonobservations of the Lockman Hole: X-ray source catalogue and number counts

A SCUBA-2 survey of FeLoBAL QSOs. Are FeLoBALs in a ‘transition phase’ between ULIRGs and QSOs?

AGN counts at 15$\mu{\rm m}$

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