Definition

Our team (Accretion History of AGN collaboration) surveyed 15.6 deg2 of the Sloan Digital Sky Survey (SDSS) field Stripe 82 with XMM-Newton in AO10 and AO13. This area is also covered by Herschel observations with the SPIRE instrument. In this survey, we have 2905 X-ray sources with optical and near-IR counterparts. Of this parent population, 805 are X-ray and optical unobscured quasars. 21 of these unobscured quasars are detected in the far-IR. We refer to these 21 galaxies as the ``Cold Quasars''. As shown in Kirkpatrick et al. (2020), Cold Quasars are rare type-1 quasars that live in starbursting galaxies. They are not well-explained by simplistic models of quasar fueling and evolution. This page contains information on the original sample, although the number of confirmed Cold Quasars has grown since then.

Optical Images

In this gallery, we show the Legacy Survey (legacysurvey.org) image (left) and Sloan Digital Sky Survey (www.sdss.org) image (right) for the original Cold Quasar sample. The Legacy Survey images are 20'x20'. They are composites from the g-band (blue), r-band (green), and z-band (red) photometric filters on the Dark Energy Camera (DECam). DECam is mounted on the Blanco 4m telescope at Cerro Tololo Inter-American Observatory. The Cerro Tololo Inter-American Observatory and the National Optical Astronomy Observatory are operated by the Association of Universities for Research in Astronomy (AURA) under cooperative agreement with the National Science Foundation. The SDSS images are composites from the g-band (blue), r-band (green), and i-band (red) photometric filters.

475
RA=01:19:48.4
Dec=+00:43:54.28
z=1.754

507
RA=01:59:37.8
Dec=+00:26:39.91
z=1.606

2435
RA=00:57:43.7
Dec=-00:11:57.92
z=1.067

2480
RA=00:58:28.9
Dec=+00:13:45.25
z=1.239

2551
RA=00:59:46.6
Dec=-00:02:54.61
z=0.682

2651
RA=01:01:13.3
Dec=-00:29:45.20
z=1.337

3122
RA=01:09:01.0
Dec=+00:01:37.44
z=2.955

3716
RA=01:19:00.4
Dec=-00:01:57.68
z=2.750

3819
RA=01:21:10.0
Dec=-00:29:10.36
z=1.719

3871
RA=01:22:49.7
Dec=-00:07:07.13
z=1.631

4077
RA=01:30:34.0
Dec=-00:21:06.61
z=3.234

4252
RA=01:35:54.4
Dec=-00:22:31.91
z=2.249

4285
RA=01:37:26.4
Dec=+00:11:52.45
z=1.103

4324
RA=01:38:14.7
Dec=+00:00:05.78
z=2.144

4336
RA=01:38:25.3
Dec=-00:05:34.39
z=1.341

4472
RA=01:40:33.8
Dec=+00:02:30.05
z=1.921

4668
RA=01:43:01.9
Dec=-00:26:56.54
z=2.786

4979
RA=01:08:21.1
Dec=-00:02:28.51
z=0.930

5074
RA=01:49:40.2
Dec=+00:17:17.76
z=1.464

5097
RA=01:49:58.3
Dec=-00:30:25.00
z=2.111

5122
RA=01:50:34.5
Dec=-00:02:00.46
z=1.740

    • Optical Spectra

    In this gallery, we show spectroscopy from the Sloan Digital Sky Survey (www.sdss.org). SDSS spectroscopy spans an observed frame wavelength range of 3800-9200 Angstroms. We shift every spectrum to the rest frame of the source, and we have labeled a few key broadlines.

    Far-IR Images

    In this gallery, we show the 250µm, 350µm, and 500µm images from the Herschel Stripe82 Survey (HerS); see Viero et al. 2014 for survey details. HerS reaches a depth of 30 mJy at 250µm. The images below are 5 arcmin on each side. The black cross marks the location of the X-ray source.

    475
    S250=49±10 mJy
    S350=40±10 mJy
    S500=29±11 mJy
    z=1.754

    507
    S250=63±11 mJy
    S350=61±10 mJy
    S500=49±11 mJy
    z=1.606

    2435
    S250=94±10 mJy
    S350=62±10 mJy
    S500=27±11 mJy
    z=1.067

    2480
    S250=37±10 mJy
    S350=17±10 mJy
    S500=2±11 mJy
    z=1.239

    2551
    S250=61±10 mJy
    S350=33±10 mJy
    S500=25±11 mJy
    z=0.682

    2651
    S250=33±10 mJy
    S350=25±11 mJy
    S500=17±12 mJy
    z=1.337

    3122
    S250=60±11 mJy
    S350=40±10 mJy
    S500=9±11 mJy
    z=2.955

    3716
    S250=35±10 mJy
    S350=41±10 mJy
    S500=27±11 mJy
    z=2.750

    3819
    S250=30±10 mJy
    S350=22±10 mJy
    S500=6±10 mJy
    z=1.719

    3871
    S250=30±10 mJy
    S350=22±10 mJy
    S500=6±10 mJy
    z=1.631

    4077
    S250=41±10 mJy
    S350=22±10 mJy
    S500=21±11 mJy
    z=3.234

    4252
    S250=38±11 mJy
    S350=34±11 mJy
    S500=48±13 mJy
    z=2.249

    4285
    S250=49±11 mJy
    S350=17±11 mJy
    S500=10±12 mJy
    z=1.103

    4324
    S250=65±11 mJy
    S350=57±11 mJy
    S500=30±12 mJy
    z=2.144

    4336
    S250=43±10 mJy
    S350=30±10 mJy
    S500=13±11 mJy
    z=1.341

    4472
    S250=57±11 mJy
    S350=53±11 mJy
    S500=18±12 mJy
    z=1.921

    4668
    S250=44±11 mJy
    S350=28±11 mJy
    S500=15±12 mJy
    z=2.786

    4979
    S250=38±11 mJy
    S350=16±11 mJy
    S500=17±12 mJy
    z=0.930

    5074
    S250=37±10 mJy
    S350=23±10 mJy
    S500=23±11 mJy
    z=1.464

    5097
    S250=49±10 mJy
    S350=42±10 mJy
    S500=37±11 mJy
    z=2.111

    5122
    S250=61±11 mJy
    S350=42±11 mJy
    S500=15±12 mJy
    z=1.740

    Spectral Decomposition

    In this gallery, we show the SED3FIT (Berta et al. 2013) decomposition of each quasar. SED3FIT is a modification of MAGPHYS (da Cunha et al. 2008) with AGN torus models. It fits a combination of stellar, dust, and AGN emission to the UV/optical/IR using an energy balance model. We also used the CIGALE decomposition code (Boquien et al. 2019) to fit the cold quasars, with similar results. Both decomposition codes fail to accurately reproduce the optical/far-IR emission of all cold quasars. In some cases, the optical emission is modeled as stellar + obscured AGN, where the spectroscopy from SDSS indicate it should be an unobscured AGN. In other cases, the far-IR emission is under-predicted. In general, we find that these sources are not well represented by current SED decomposition codes. In Kirkpatrick et al. 2020, we instead measured star formation rates using a bespoke IR decomposition that included substantial far-IR AGN heating.