Optical – near-infrared catalog for the AKARI north ecliptic pole Deep field

Abstract

Aims. We present an 8-band (u * , g , r , i , z , Y, J, K s ) optical to near-infrared deep photometric catalog based on the observations made with MegaCam and WIRCam at the CFHT, and compute photometric redshifts, z p in the north ecliptic pole (NEP) region. AKARI infrared satellite carried out a deep survey in the NEP region at near-to mid-infrared wavelengths. Our optical to nearinfrared catalog allows us to identify the counterparts and z p for the AKARI sources. Methods. We obtained seven-band (g , r , i , z , Y, J, K s ) imaging data, and we crossmatched them with existing u * -band data (limiting magnitude = 24.6 mag [5σ; AB]) to design the band-merged catalog. We included all z -band sources with counterparts in at least one of the other bands in the catalog. We used a template-fitting methods to compute z p for all the cataloged sources. Results. The estimated 4σ detection limits within a 1 arcsec aperture radius are 26.7, 25.9, 25.1, and 24.1 mag [AB] for the optical g , r , i , and z -bands and 23.4, 23.0, and 22.7 mag for the near-infrared Y, J, and K s -bands, respectively. There are a total of 85 797 sources in the band-merged catalog. An astrometric accuracy of this catalog determined by examining coordinate offsets with regard to 2MASS is 0.013 arcsec with a root mean square offset of 0.32 arcsec. We distinguish 5441 secure stars from extended sources using the u * − J versus g − K s colours, combined with the SExtractor stellarity index of the images. Comparing with galaxy spectroscopic redshifts, we find a photometric redshift dispersion, σ Δz/(1+z) , of 0.032 and catastrophic failure rate, Δz 1+z > 0.15, of 5.8% at z < 1, while a dispersion of 0.117 and a catastrophic failure rate of 16.6% at z > 1. We extend the estimate of the z p uncertainty over the full magnitude/redshift space with a redshift probability distribution function and find that our redshifts are highly accurate with z < 22 at z p < 2.5 and for fainter sources with z < 24 at z p < 1. From the investigation of photometric properties of AKARI infrared sources (23 354 sources) using the g z K s diagram, < 5% of AKARI sources with optical counterparts are classified as high-z (1.4 < z < 2.5) star-forming galaxies. Among the high-z star-forming galaxies, AKARI mid-infrared detected sources seem to be affected by stronger dust extinction compared with sources with non-detections in the AKARI mid-infrared bands.

Hyper Suprime-Camera Survey of the Akari Nep Wide Field

“…Our experience in the central Suprimecam field predicts photo-z accuracy of ∆z 1+z ∼0.036 is achievable from 5-broad band photometry (Oi et al, 2014). …”

“…We are studying the multi-band data of these mid-IR galaxies as shown in Table 1 (Takagi et al, 2010;Goto et al, 2010b). However, because very dusty objects cannot be detected in the relatively shallow CFHT imaging data (r <25.9ABmag; Hwang et al, 2007;Jeon et al, 2010;Oi et al, 2014), there remain 11,000 AKARI sources undetected in the optical. As a result, we lack an understanding of the redshift and IR luminosity of these sources, i.e., they have been excluded from the past cosmic star formation history (CSFH) analysis.…”

The Radio-Far Infrared Correlation in the Nep Deep Field

“…We have cross-correlated for positional matches using an optical catalogue as a reference, and matched these with photometric redshift catalogues (Oi et al, 2014) to study the relationship between the radio and FIR luminosities. Since there is evidence for the FIR-radio correlation in other data sets (Ivison et al, 2010), we have checked this correlation for each AKARI and Herschel band.…”

Akari-Nep : Effects of Agn Presence on SFR Estimates of Galaxies

“…For this reason we use the multi-wavelength AKARI catalogue assembled by Murata et al (2013) in the deep survey area, which covers only the central region of the area observed with Herschel, together with the shal- lower collection by Kim et al (2012) which covers a larger area than the deep one (see Oi et al 2014 for the coverage map). These catalogues contain photometry from the optical to the AKARI L24 filter.…”

“…These catalogues contain photometry from the optical to the AKARI L24 filter. Oi et al (2014) also provide the photometric redshifts for all the sources in the deep catalogue. We then add the catalogue of spectroscopic redshifts by Shim et al (2013) and the UV GALEX photometry by Mazyed et al, in preparation.…”