Photometric Redshifts in the IRAC Shallow Survey

Brodwin, M.; Brown, M. J. I.; Ashby, M. L. N.; Bian, Chao; Brand, Kate; Dey, Arjun; Eisenhardt, Peter; Eisenstein, Daniel J.; Gonzalez, Anthony H.; Huang, Jia-Sheng; Jannuzi, Buell T.; Kochanek, C. S.; McKenzie, Eric; Murray, Stephen S.; Pahre, M. A.; Smith, H. A.; Soifer, B. T.; Stanford, S. A.; Stern, Daniel; Elston, R.

doi:10.1086/507838

Cited by 163 publications

(273 citation statements)

References 55 publications

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“…Today, there are two independent efforts aiming to detect galaxy clusters using IR data: the IRAC Shallow Cluster Survey (ISCS; Eisenhardt et al, 2008) and the Spitzer Adaptation of the Red-Sequence Cluster Survey (SpARCS; Wilson et al, 2006). Both surveys have discovered and spectroscopically confirmed candidate galaxy clusters out to redshift z 1.5 (e.g., Stanford et al, 2005;Brodwin et al, 2006;Eisenhardt et al, 2008;Muzzin et al, 2009;Wilson et al, 2009;Demarco et al, 2010), with some recent detections reaching z 2 Zeimann et al, 2012). Additionally, some of these systems have also been detected in X-rays and/or SZ (Brodwin et al, 2011;Andreon and Moretti, 2011;Brodwin et al, 2012).…”

Section: The Current State Of Playmentioning

confidence: 98%

Observational probes of cosmic acceleration

et al. 2013

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The accelerating expansion of the universe is the most surprising cosmological discovery in many decades, implying that the universe is dominated by some form of "dark energy" with exotic physical properties, or that Einstein's theory of gravity breaks down on cosmological scales. The profound implications of cosmic acceleration have inspired ambitious efforts to understand its origin, with experiments that aim to measure the history of expansion and growth of structure with percent-level precision or higher. We review in detail the four most well established methods for making such measurements: Type Ia supernovae, baryon acoustic oscillations (BAO), weak gravitational lensing, and the abundance of galaxy clusters. We pay particular attention to the systematic uncertainties in these techniques and to strategies for controlling them at the level needed to exploit "Stage IV" dark energy facilities such as BigBOSS, LSST, Euclid, and WFIRST. We briefly review a number of other approaches including redshift-space distortions, the Alcock-Paczynski effect, and direct measurements of the Hubble constant H 0 . We present extensive forecasts for constraints on the dark energy equation of state and parameterized deviations from General Relativity, achievable with Stage III and Stage IV experimental programs that incorporate supernovae, BAO, weak lensing, and cosmic microwave background data. We also show the level of precision required for clusters or other methods to provide constraints competitive with those of these fiducial programs. We emphasize the value of a balanced program that employs several of the most powerful methods in combination, both to cross-check systematic uncertainties and to take advantage of complementary information. Surveys to probe cosmic acceleration produce data sets that support a wide range of scientific investigations, and they continue the longstanding astronomical tradition of mapping the universe in ever greater detail over ever larger scales.

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Section: The Current State Of Playmentioning

confidence: 98%

Observational probes of cosmic acceleration

et al. 2013

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“…Of these, 5 have 5 detections in the IRAC bands, and 4 have IRAC colors inside the S05 selection region. These four sources have photo-z estimates from the Brodwin et al (2006) catalog, although only two are in our IRAGN 2 sample (the other two have no detection in the R band). Of the IRAGN 2s, one has R ¼ 23:8 and (z spec ; z phot ) ¼ (1:95; 2:35) while the other has R ¼ 24:7 and (z spec ; z phot ) ¼ (2:59; 3:96).…”

Section: Comparison Of Spectroscopic and Photometric Redshiftsmentioning

confidence: 99%

A Large Population of Mid‐Infrared–selected, Obscured Active Galaxies in the Bootes Field

Hickox

Jones

Forman

et al. 2007

ApJ

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We identify a population of 640 obscured and 839 unobscured AGNs at redshifts 0:7 < z P 3 using multiwavelength observations of the 9 deg 2 NOAO Deep Wide-Field Survey ( NDWFS) region in Boötes. We select AGNs on the basis of Spitzer IRAC colors obtained by the IRAC Shallow Survey. Redshifts are obtained from optical spectroscopy or photometric redshift estimators. We classify the IR-selected AGNs as IRAGN 1 (unobscured) and IRAGN 2 (obscured) using a simple criterion based on the observed optical to mid-IR color, with a selection boundary of R À ½4:5 ¼ 6:1, where R and [4.5] are the Vega magnitudes in the R and IRAC 4.5 m bands, respectively. We verify this selection using X-ray stacking analyses with data from the Chandra XBoötes survey, as well as optical photometry from NDWFS and spectroscopy from MMT/AGES. We show that (1) these sources are indeed AGNs, and (2) the optical /IR color selection separates obscured sources (with average N H $ 3 ; 10 22 cm À2 obtained from X-ray hardness ratios, and optical colors and morphologies typical of galaxies) and unobscured sources (with no X-ray absorption, and quasar colors and morphologies), with a reliability of k80%. The observed numbers of IRAGNs are comparable to predictions from previous X-ray, optical, and IR luminosity functions, for the given redshifts and IRAC flux limits. We observe a bimodal distribution in R À ½4:5 color, suggesting that luminous IR-selected AGNs have either low or significant dust extinction, which may have implications for models of AGN obscuration.

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“…With respect to existing template libraries derived from empirical SEDs (Coleman et al 1980) or from models ( Bruzual & Charlot 2003;Fioc & Rocca-Volmerange 1997;Silva et al 1998;Devriendt et al 1999), this library has a broader wavelength coverage and variety of spectral types. Examples of application of this library to various types of SWIRE sources can be found in Photometric redshift techniques have been applied to optical or optical and near-IR data sets, providing reliable photometric redshifts (Rowan-Robinson et al 2005;Ilbert et al 2006;Brodwin et al 2006). However, with a limited wavelength coverage, some spectral types can be degenerate, e.g., obscured starbursts and ellipticals.…”

Section: Template Fitting and Photometric Redshift Techniquementioning

confidence: 99%

Spectral Energy Distributions of Hard X‐Ray Selected Active Galactic Nuclei in theXMM‐NewtonMedium Deep Survey

Polletta

Tajer

Maraschi

et al. 2007

ApJ

836

1,088

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We present the SEDs of a hard X-ray selected sample containing 136 sources with F 2Y10 keV > 10 À14 erg cm À2 s À1 ; 132 are AGNs. The sources are detected in a 1 deg 2 area of the XMM-Newton Medium Deep Survey where optical data from the VVDS and CFHTLS and infrared data from the SWIRE survey are available. Based on a SED fitting technique we derive photometric redshifts with (1 þ z) ¼ 0:11 and 6% of outliers and identify AGN signatures in 83% of the objects. This fraction is higher than derived when a spectroscopic classification is available. The remaining 17 þ9 À6 % of AGNs show star-forming galaxy SEDs (SF class). The sources with AGN signatures are divided in two classes, AGN1 (33 þ6 À1 %) and AGN2 (50 þ6 À11 %). The AGN1 and AGN2 classes include sources whose SEDs are fitted by type 1 and type 2 AGN templates, respectively. On average, AGN1s show soft X-ray spectra, consistent with being unabsorbed, while AGN2s and SFs show hard X-ray spectra, consistent with being absorbed. The analysis of the average SEDs as a function of X-ray luminosity shows a reddening of the infrared SEDs, consistent with a decreasing contribution from the host galaxy at higher luminosities. The AGNs in the SF classes are likely obscured in the mid-infrared, as suggested by their low L 3Y20 m /L corr 0:5Y10 keV ratios. We confirm the previously found correlation for AGNs between the radio luminosity and the X-ray and the mid-infrared luminosities. The X-rayYradio correlation can be used to identify heavily absorbed AGNs. However, the estimated radio fluxes for the missing AGN population responsible for the bulk of the background at E > 10 keV are too faint to be detected even in the deepest current radio surveys.

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Photometric Redshifts in the IRAC Shallow Survey

Cited by 163 publications

References 55 publications

Observational probes of cosmic acceleration

Observational probes of cosmic acceleration

A Large Population of Mid‐Infrared–selected, Obscured Active Galaxies in the Bootes Field

Spectral Energy Distributions of Hard X‐Ray Selected Active Galactic Nuclei in theXMM‐NewtonMedium Deep Survey

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