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

Abstract

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<z<6.42 (mean: 0.48, median: 0.14). We confirm the default NED redshift for 2429 sources and identify 124 with incorrect NED redshifts. We obtain IRS-based redshifts for 568 IDEOS sources without optical spectroscopic redshifts, including 228 with no previous redshift measurements. We provide the entire IDEOS redshift catalog in machine-readable formats. The catalog condenses our compilation and verification effort, and includes our final evaluation on the most likely redshift for each source, its origin, and reliability estimates.

Mid-infrared spectroscopic evidence for AGN heating warm molecular gas

“…We use MIR spectroscopy to evaluate the relationship between AGN and the ISM of their host galaxies. We analyse 2,015 objects low-resolution spectra (Lebouteiller et al 2011) with published spectroscopic redshifts (Hernán-Caballero et al 2016). We correct mismatches between the different spectral orders and check the flux calibration of the spectra using WISE photometry.…”

“…In Table 1 we provide the AORkeys, coordinates, redshift, and other general sample properties. The Infrared Database of Extragalactic Observables (IDEOS) has a redshift catalogue for all the spectra in CASSIS (Hernán-Caballero et al 2016). The IDEOS redshift catalogue was compiled by comparing with the NASA/IPAC Extragalactic Database redshifts and optical counterparts, providing IRS redshifts with accuracy σ z ∼ 0.0011.…”

The near-to-mid infrared spectrum of quasars

“…Database (NED), and validated with the Spitzer/IRS spectrum using cross-correlation with templates (see Hernán-Caballero 2012;Hernán-Caballero et al 2016 …”

“…We stitch the different orders in the Spitzer/IRS spectra following the procedure described in Hernán-Caballero et al (2016). Very briefly, we take the LL2 spectrum as reference and scale the three SL modules to match the SL1 and LL2 spectra in the overlap region.…”

Extinction in the 11.2 micron PAH band and the low L_11.2/L_IR in ULIRGs

“…IDEOS provides homogeneously measured spectroscopic observables for nearly all the galaxies beyond the Local Group that were observed with the Infrared Spectrograph (IRS; Houck et al 2004) onboard Spitzer using the low-resolution R ∼ 60-120 modules. 2 The stitching of the different spectral orders in the Spitzer /IRS spectra, cross-identification with the NASA Extragalactic Database (NED), and determination and validation of redshifts is presented in Hernán-Caballero et al (2016).…”