The Massive Hosts of Radio Galaxies across Cosmic Time

Seymour, N.; Stern, Daniel; Breuck, C. De; Vernet, J.; Rettura, Alessandro; Dickinson, Mark; Dey, Arjun; Eisenhardt, Peter; Fosbury, R. A. E.; Lacy, Mark; McCarthy, P. J.; Miley, G. K.; Rocca‐Volmerange, B.; Röttgering, H. J. A.; Stanford, S. A.; Teplitz, Harry I.; Breugel, Wil van; Zirm, A.

doi:10.1086/517887

Cited by 243 publications

(320 citation statements)

References 126 publications

(158 reference statements)

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“…This suggests that although we are missing a significant fraction of the X-ray luminous AGN, we are indeed selecting the same AGN population as that of low-mass emission-line AGN that have been recognised as AGN which have radiatively efficient accretion ("Quasar mode", Heckman et al 2004;Best et al 2005). This picture is supported by the result (ii) on the infrared properties of X-ray selected AGN: these objects have a hot dust component at wavelength as short as 3.6 μm (observer frame), which is often interpreted as being due to an actively accreting black hole where UV light heats the surrounding dust to temperatures of 500−1000 K (Seymour et al 2007). Result (iii) suggests that these AGN are mainly located in large 450 kpc scale underdensities at levels of ∼−0.5.…”

Section: Summary and Discussionmentioning

confidence: 75%

The dependence of X-ray AGN activity on host galaxy properties and environment

Tasse

Röttgering

Best

2010

A&A

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There is mounting evidence that active galactic nuclei (AGN) selected through optical emission lines or radio luminosities comprise two distinct AGN populations, whose activity is triggered by different processes. In two previous papers, we studied the host galaxies and environment of radio-loud AGN. In this third paper we study the properties of a sample of Type-2 AGN that were selected on the basis of their [2-10] keV X-ray luminosity. We find that the X-ray luminosity function is in good agreement with previous studies and that the fraction of galaxies hosting an X-ray AGN is a strong function of the stellar mass of the host galaxy. The shape of this fraction-mass relation is similar to the fraction of galaxies that are emission-line AGN, while it differs significantly from the relation observed for radio-selected AGN. The AGN in our sample tend to be located in underdense environments where galaxy mergers and interactions are likely to occur. For all host galaxy masses, the Type-2 AGN display a strong infrared excess at short (∼3.5 μm) wavelengths, suggesting the presence of hot dust possibly associated with a hot dusty torus. These results add weight to the belief that the X-ray selection criteria identifies a population of AGN similar to the emission-line selected population but distinct from the radio population at high masses.

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Section: Summary and Discussionmentioning

confidence: 75%

The dependence of X-ray AGN activity on host galaxy properties and environment

Tasse

Röttgering

Best

2010

A&A

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“…In both scenarios, the largest disk radii or merger separation yield dynamical masses that correspond to the upper end of the mass function at high redshift (Seymour et al 2007). Furthermore, they would be even higher if the systems were less inclined (i ≤ 90 • ).…”

Section: Dynamical Massesmentioning

confidence: 97%

Disk, merger, or outflow? Molecular gas kinematics in two powerful obscured QSOs atz ≥ 3.4

Polletta

Nesvadba

Neri

et al. 2011

A&A

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We report on the detection of bright CO(4-3) line emission in two powerful, obscured quasars discovered in the SWIRE survey, SW022513 and SW022550 at z ≥ 3.4. We analyze the line strength and profile to determine the gas mass, dynamical mass, and the gas dynamics for both galaxies. In SW022513 we may have found the first evidence for a molecular, AGN-driven wind in the early Universe. The line profile in SW022513 is broad (FWHM = 1000 km s −1 ) and blueshifted by −200 km s −1 relative to systemic (where the systemic velocity is estimated from the narrow components of ionized gas lines, as is commonly done for AGN at low and high redshifts). SW022550 has a more regular, double-peaked profile, which is marginally spatially resolved in our data, consistent with either a merger or an extended disk. The molecular gas masses, 4×10 10 M , are large and account for <30% of the stellar mass, making these obscured QSOs as gas rich as other powerful CO emitting galaxies at high redshift, i.e., submillimeter galaxies. Our sources exhibit relatively lower star-formation efficiencies compared to other dusty, powerful starburst galaxies at high redshift. We speculate that this could be a consequence of the AGN perturbing the molecular gas.

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“…The stellar bump luminosity at 1.6 μm (ν L ν (1.6 μm), reported in Table 5, gives an estimate of the stellar mass (M ) of our sources (see, e.g., F09; Seymour et al 2007;Lonsdale et al 2009). Applying the same mass-to-light ratio as F09 (M /ν L ν (1.6 μm) = 0.7 M /L ), M derived from ν L ν (1.6 μm) ranges from 1.1 to 3.0 × 10 11 M (average = 1.6 × 10 11 M , median = 1.4 × 10 11 M ).…”

Section: Pah Emission and Stellar Massmentioning

confidence: 99%

Mid-infrared spectroscopy ofSpitzer-selected ultra-luminous starbursts atz ~ 2

Fiolet

Omont

Lagache

et al. 2010

A&A

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Context. Spitzer's wide-field surveys and followup capabilities have allowed a new breakthrough in mid-IR spectroscopy up to redshifts ≥2, especially for 24 μm detected sources. Aims. We want to study the mid-infrared properties and the starburst and AGN contributions, of 24 μm sources at z ∼ 2, through analysis of mid-infrared spectra combined with millimeter, radio, and infrared photometry. Mid-infrared spectroscopy allows us to recover accurate redshifts. Methods. A complete sample of 16 Spitzer-selected sources (ULIRGs) believed to be starbursts at z ∼ 2 ("5.8 μm-peakers") was selected in the (0.5 deg 2 ) J1064+56 SWIRE Lockman Hole field ("Lockman-North"). These sources have S 24 μm > 0.5 mJy, a stellar emission peak redshifted to 5.8 μm, and r Vega > 23. The entire sample was observed with the low resolution units of the Spitzer/IRS infrared spectrograph. These sources have 1.2 mm observations with IRAM 30 m/MAMBO and very deep 20 cm observations from the VLA. Nine of our sources also benefit from 350 μm observation and detection from CSO/SHARC-II. All these data were jointly analyzed.Results. The entire sample shows good quality IRS spectra dominated by strong PAH features. The main PAH features at 6.2, 7.7, 8.6, and 11.3 μm have high S /N average luminosities of 2.90 ± 0.31, 10.38 ± 1.09, 3.62 ± 0.27, and 2.29 ± 0.26 × 10 10 L , respectively. Thanks to their PAH spectra, we derived accurate redshifts spanning from 1.750 to 2.284. The average of these redshifts is 2.017 ± 0.038. This result confirms that the selection criteria of "5.8 μm-peakers" associated with a strong detection at 24 μm are reliable to select sources at z ∼ 2. We have analyzed the different correlations between PAH emission and infrared, millimeter, and radio emissions. Practically all our sources are strongly dominated by starburst emission, with only one source showing an important AGN contribution. We have also defined two subsamples based on the equivalent width at 7.7 μm to investigate AGN contributions. Conclusions. Our sample contains strong starbursts and represents a particularly 24 μm-bright class of SMGs. The very good correlation between PAH and far-IR luminosities is now confirmed in high-z starburst ULIRGs. These sources show a small AGN contribution to the mid-IR, around ∼20% or less in most cases.

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The Massive Hosts of Radio Galaxies across Cosmic Time

Cited by 243 publications

References 126 publications

The dependence of X-ray AGN activity on host galaxy properties and environment

The dependence of X-ray AGN activity on host galaxy properties and environment

Disk, merger, or outflow? Molecular gas kinematics in two powerful obscured QSOs atz ≥ 3.4

Mid-infrared spectroscopy ofSpitzer-selected ultra-luminous starbursts atz ~ 2

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