The Reddest DR3 SDSS/<i>XMM‐Newton</i>Quasars

Young, M.; Elvis, M.; Risaliti, G.

doi:10.1086/592083

Cited by 21 publications

(26 citation statements)

References 83 publications

(130 reference statements)

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“…Wilkes et al (2002) and Rose et al (2013) suggested that the red J − K colors (J − K > 2) of red quasars come from a moderate viewing angle in the unification model when the photons from the accretion disk and the BLR are blocked by the dust torus and not by the dust in host galaxies. Other studies suggest that some (∼40%; Young et al 2008) red quasars have intrinsically red continuum (Puchnarewicz & Mason 1998;Whiting et al 2001;Young et al 2008;Rose et al 2013;Ruiz et al 2014) or an unusual covering factor of hot dust (Rose 2014). Also a synchrotron emission peak at NIR wavelength from radio jet (Whiting et al 2001) has been proposed as a possible reason for the intrinsically red continuum of red quasars.…”

Section: Introductionmentioning

confidence: 99%

“…However, our knowledge about quasars is still incomplete, especially with a population of quasars called red quasars, which have been identified in recent infrared surveys Full Table A.1 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/610/A31 (Webster et al 1995;Benn et al 1998;Cutri et al 2001;Glikman et al 2007Glikman et al , 2012Glikman et al , 2013Urrutia et al 2009;Banerji et al 2012;Stern et al 2012;Assef et al 2013;Fynbo et al 2013;Lacy et al 2013). Red quasars typically indicate quasars with red continua from UV or optical through NIR (e.g., r − K > 5 mag and J − K > 1.3 mag in Urrutia et al 2009; g − r > 0.5 in Young et al 2008), red mid-infrared (MIR) colors (Lacy et al 2004), or detections in X-rays while being obscured in UV and optical wavelengths (Norman et al 2002;Anderson et al 2003;Risaliti & Elvis 2005;Young et al 2009;Brusa et al 2010).…”

Section: Introductionmentioning

confidence: 99%

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What makes red quasars red?

Kim

2018

A&A

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Red quasars are very red in the optical through near-infrared (NIR) wavelengths, which is possibly due to dust extinction in their host galaxies as expected in a scenario in which red quasars are an intermediate population between merger-driven star-forming galaxies and unobscured type 1 quasars. However, alternative mechanisms also exist to explain their red colors: (i) an intrinsically red continuum; (ii) an unusual high covering factor of the hot dust component, that is, CFHD = LHD∕Lbol, where the LHD is the luminosity from the hot dust component and the Lbol is the bolometric luminosity; and (iii) a moderate viewing angle. In order to investigate why red quasars are red, we studied optical and NIR spectra of 20 red quasars at z ~ 0.3 and 0.7, where the usage of the NIR spectra allowed us to look into red quasar properties in ways that are little affected by dust extinction. The Paschen to Balmer line ratios were derived for 13 red quasars and the values were found to be ~10 times higher than unobscured type 1 quasars, suggesting a heavy dust extinction with AV > 2.5 mag. Furthermore, the Paschen to Balmer line ratios of red quasars are difficult to explain with plausible physical conditions without adopting the concept of the dust extinction. The CFHD of red quasars are similar to, or marginally higher than, those of unobscured type 1 quasars. The Eddington ratios, computed for 19 out of 20 red quasars, are higher than those of unobscured type 1 quasars (by factors of 3−5), and hence the moderate viewing angle scenario is disfavored. Consequently, these results strongly suggest the dust extinction that is connected to an enhanced nuclear activity as the origin of the red color of red quasars, which is consistent with the merger-driven quasar evolution scenario.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

What makes red quasars red?

Kim

2018

A&A

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“…There are a number of possible reasons for the red colours of rQSOs, such as intrinsically cooler accretion discs, host galaxy light, or Doppler-boosted synchrotron emission (e.g. Benn et al 1998;Francis et al 2001;Young, Elvis & Risaliti 2008), but the vast majority of luminous rQSOs are reddened by intervening dust (Richards et al 2003;Glikman et al 2004Glikman et al , 2012Rose et al 2013;Kim & Im 2018;Klindt et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Fundamental differences in the radio properties of red and blue quasars: kiloparsec-scale structures revealed by e-MERLIN

Rosario

Alexander

Moldón

et al. 2021

Monthly Notices of the Royal Astronomical Society

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Red quasi-stellar objects (QSOs) are a subset of the quasar population with colours consistent with reddening due to intervening dust. Recent work has demonstrated that red QSOs show special radio properties that fundamentally distinguish them from normal blue QSOs, specifically a higher incidence of low-power radio emission (1.4 GHz luminosities L1.4≈1025 – 1027 W Hz−1) that is physically compact when imaged by arcsecond-resolution radio surveys such as FIRST. In this work, we present e-MERLIN imaging of a set of intermediate-redshift (1.0 < z < 1.55), luminous (bolometric luminosities Lbol ≈ 1046 – 1047 erg s−1) red and normal QSOs carefully selected to have radio properties that span the range over which red QSOs show the most divergence from the general population. With an angular resolution × 25 better than FIRST, we resolve structures within the host galaxies of these QSOs (>2 kpc). We report a statistically significant difference in the incidence of extended kpc-scale emission in red QSOs. From an analysis of the radio size distributions of the sample, we find that the excess radio emission in red QSOs can be attributed to structures that are confined to galaxy scales (<10 kpc), while we confirm previous results that red and normal QSOs have similar incidences of radio jets and lobes on circumgalactic or larger scales (>10 kpc). Our results indicate that the primary mechanism that generates the enhanced radio emission in red QSOs is not directly connected with the nuclear engine or accretion disc, but is likely to arise from extended components such as AGN-driven jets or winds.

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“…For many of these types of sources, there is an ongoing debate about whether (some of) these red QSOs are obscured by either dust or an intrinsically red continuum (Richards et al 2003;Young et al 2008). Thus, our multiband template fit takes into account the possibility of intrinsic dust obscuration within the source.…”

Section: Extinctionmentioning

confidence: 99%

Quasi-stellar objects in the ALHAMBRA survey

Matute

Márquez

Masegosa

et al. 2012

A&A

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Context. Even the spectroscopic capabilities of today's ground and space-based observatories can not keep up with the enormous flow of detections (>10 5 deg −2 ) unveiled in modern cosmological surveys as: i) would be required enormous telescope time to perform the spectroscopic follow-ups and ii) spectra remain unattainable for the fainter detected population. In the past decade, the typical accuracy of photometric redshift (photo-z) determination has drastically improved. Nowdays, it has become a perfect complement to spectroscopy, closing the gap between photometric surveys and their spectroscopic follow-ups. The photo-z precision for active galactic nuclei (AGN) has always lagged behind that for the galaxy population owing to the lack of proper templates and their intrinsic variability. Aims. Our goal is to characterize the ability of the Advanced Large, Homogeneous Area Medium-Band Redshift Astronomical (ALHAMBRA) survey in assigning accurate photo-z's to broad-line AGN (BLAGN) and quasi-stellar objects (QSOs) based on their ALHAMBRA very-low-resolution optical-near-infrared (NIR) spectroscopy. This will serve as a benchmark for any future compilation of ALHAMBRA selected QSOs and the basis for the statistical analysis required to derive luminosity functions up to z ∼ 5. Methods. We selected a sample of spectroscopically identified BLAGN and QSOs and used a library of templates (including the SEDs of AGN and both normal and starburst galaxies, as well as stars) to fit the 23 photometric data points provided by ALHAMBRA in the optical and NIR (20 medium-band optical filters plus the standard JHKs). Results. We find that the ALHAMBRA photometry is able to provide an accurate photo-z and spectral classification for ∼88% of the 170 spectroscopically identified BLAGN/QSOs over 2.5 deg 2 in different areas of the survey and brighter than m 678 = 23.5 (equivalent to r SLOAN ∼ 24.0). The derived photo-z accuracy is below 1% and is comparable to the most recent results in other cosmological fields that use photometric information over a wider wavelength range. The fraction of outliers (∼12%) is mainly caused by the larger photometric errors for the faintest sources and the intrinsic variability of the BLAGN/QSO population. A small fraction of outliers may have an incorrectly assigned spectroscopic redshift. Conclusions. The definition of the ALHAMBRA survey in terms of the number of filters, filter properties, areal coverage, and depth is able to provide photometric redshifts for BLAGN/QSOs with a precision similar to any previous survey that makes use of mediumband optical photometry. In agreement with previous literature results, our analysis also reveals that, in the 0 < z < 4 redshift interval, very accurate photo-z can be obtained without the use of NIR broadband photometry at the expense of a slight increase in the outliers. The importance of NIR data is expected to increase at higher z (z > 4). These results are relevant for the design of future optical follow-ups of surveys containing a large fractio...

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The Reddest DR3 SDSS/XMM‐NewtonQuasars

Cited by 21 publications

References 83 publications

What makes red quasars red?

What makes red quasars red?

Fundamental differences in the radio properties of red and blue quasars: kiloparsec-scale structures revealed by e-MERLIN

Quasi-stellar objects in the ALHAMBRA survey

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