The Chain of Custody

Houck, Max M.; Crispino, Frank; McAdam, Terry

doi:10.1016/b978-0-12-386464-2.00012-4

Cited by 2 publications

(2 citation statements)

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“…These are mostly optically faint, highredshift sources that were observed by several programs targeting (ultra-)luminous infrared galaxies (e.g. Houck et al 2005;Weedman et al 2006;Yan et al 2007;Farrah et al 2008;Dasyra et al 2009;Hernán-Caballero et al 2009;Weedman et al 2009). While these redshifts are spectroscopic in nature, we consider them separately because they are usually based on the visual identification of PAH features or the 9.8µm silicate absorption band, and their uncertainties (∆z/(1+z)∼0.01-0.1) are large compared to both our z IRS measurements and regular optical/radio spectroscopy.…”

Section: Redshifts From Nasa Extragalactic Databasementioning

confidence: 99%

The infrared database of extragalactic observables from Spitzer – I. The redshift catalogue

Hernán-Caballero

Spoon

Lebouteiller

et al. 2015

Monthly Notices of the Royal Astronomical Society

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This is the first of a series of papers on the Infrared Database of Extragalactic Observables from Spitzer (IDEOS). In this work we describe the identification of optical counterparts of the infrared sources detected in Spitzer Infrared Spectrograph (IRS) observations, and the acquisition and validation of redshifts. The IDEOS sample includes all the spectra from the Cornell Atlas of Spitzer/IRS Sources (CASSIS) of galaxies beyond the Local Group. Optical counterparts were identified from correlation of the extraction coordinates with the NASA Extragalactic Database (NED). To confirm the optical association and validate NED redshifts, we measure redshifts with unprecedented accuracy on the IRS spectra (σ(∆z/(1+z))∼0.0011) by using an improved version of the maximum combined pseudo-likelihood method (MCPL). We perform a multi-stage verification of redshifts that considers alternate NED redshifts, the MCPL redshift, and visual inspection of the IRS spectrum. The statistics is as follows: the IDEOS sample contains 3361 galaxies at redshift 0

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Section: Redshifts From Nasa Extragalactic Databasementioning

confidence: 99%

The infrared database of extragalactic observables from Spitzer – I. The redshift catalogue

Hernán-Caballero

Spoon

Lebouteiller

et al. 2015

Monthly Notices of the Royal Astronomical Society

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“…The above methods have been successful in selecting a wide variety of AGN, but nevertheless miss certain populations, such as very heavily obscured AGN and LLAGN (e.g., Bauer et al 2004;Alexander et al 2005;Lehmer et al 2008). While heavily obscured AGN can often be selected in the IR (e.g., Houck et al 2005;Martinez-Sansigre et al 2005;Alexander et al 2008), the spectral energy distributions (SEDs) of LLAGN are likely dominated by the host galaxy in other bands. Even in X-rays, X-ray binaries, ultraluminous X-ray sources, and hot gas will provide significant contributions to the overall power output.…”

Section: Introductionmentioning

confidence: 99%

VARIABILITY-SELECTED LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI IN THE 4 Ms CHANDRA DEEP FIELD-SOUTH

Young

Brandt

Xue

et al. 2012

ApJ

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The 4 Ms Chandra Deep Field-South (CDF-S) and other deep X-ray surveys have been highly effective at selecting active galactic nuclei (AGN). However, cosmologically distant low-luminosity AGN (LLAGN) have remained a challenge to identify due to significant contribution from the host galaxy. We identify long-term X-ray variability (∼month-years, observed frame) in 20 of 92 CDF-S galaxies spanning redshifts z ≈ 0.08 − 1.02 that do not meet other AGN selection criteria. We show that the observed variability cannot be explained by X-ray binary populations or ultraluminous X-ray sources, so the variability is most likely caused by accretion onto a supermassive black hole. The variable galaxies are not heavily obscured in general, with a stacked effective power-law photon index of Γ stack ≈ 1.93 ± 0.13, and are therefore likely LLAGN. The LLAGN tend to lie a factor of ≈6-80 below the extrapolated linear variability-luminosity relation measured for luminous AGN. This may be explained by their lower accretion rates. Variability-independent black-hole mass and accretion-rate estimates for variable galaxies show that they sample a significantly different blackhole mass-accretion rate space, with masses a factor of 2.4 lower and accretion rates a factor of 22.5 lower than variable luminous AGN at the same redshift. We find that an empirical model based on a universal broken power-law PSD function, where the break frequency depends on SMBH mass and accretion rate, roughly reproduces the shape, but not the normalization, of the variability-luminosity trends measured for variable galaxies and more luminous AGN.

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The Chain of Custody

Cited by 2 publications

References 0 publications

The infrared database of extragalactic observables from Spitzer – I. The redshift catalogue

The infrared database of extragalactic observables from Spitzer – I. The redshift catalogue

VARIABILITY-SELECTED LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI IN THE 4 Ms CHANDRA DEEP FIELD-SOUTH

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