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Register a new userAssessing the photometric redshift precision of the S-PLUS survey: the Stripe-82 as a test-case
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In this paper we present a thorough discussion about the photometric redshift (photo-z) performance of the Southern Photometric Local Universe Survey (S-PLUS). This survey combines a 7 narrow + 5 broad passband filter system, with a typical photometric-depth of r$sim$21 AB. For this exercise, we utilize the Data Release 1 (DR1), corresponding to 336 deg$^{2}$ from the Stripe-82 region. We rely on the texttt{BPZ2} code to compute our estimates, using a new library of SED models, which includes additional templates for quiescent galaxies. When compared to a spectroscopic redshift control sample of $sim$100k galaxies, we find a precision of $sigma_{z}<$0.8%, $<$2.0% or $<$3.0% for galaxies with magnitudes r$<$17, $<$19 and $<$21, respectively. A precision of 0.6% is attained for galaxies with the highest texttt{Odds} values. These estimates have a negligible bias and a fraction of catastrophic outliers inferior to 1%. We identify a redshift window (i.e., 0.26$<z<$0.32) where our estimates double their precision, due to the simultaneous detection of two emission-lines in two distinct narrow-bands; representing a window opportunity to conduct statistical studies such as luminosity functions. We forecast a total of $sim$2M, $sim$16M and $sim$32M galaxies in the S-PLUS survey with a photo-z precision of $sigma_{z}<$1.0%, $<$2.0% and $<$2.5% after observing 8000 $deg^{2}$. We also derive redshift Probability Density Functions, proving their reliability encoding redshift uncertainties and their potential recovering the $n(z)$ of galaxies at $z<0.4$, with an unprecedented precision for a photometric survey in the southern hemisphere.
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This work is a Brazilian-Indian collaboration. It aims at investigating the structuralproperties of Lenticular galaxies in the Stripe 82 using a combination of S-PLUS (Southern Photometric Local Universe Survey) and SDSS data. S-PLUS is a noveloptical multi-wavelength survey which will cover nearly 8000 square degrees of the Southern hemisphere in the next years and the first data release covers the Stripe 82 area. The morphological classification and study of the galaxies stellar population will be performed combining the Bayesian Spectral type (from BPZ) and Morfometryka (MFMTK) parameters. BPZ and MFMTK are two complementary techniques, since the first one determines the most likely stellar population of a galaxy, in order to obtain its photometric redshift (phot-z), and the second one recovers non-parametric morphological quantities, such as asymmetries and concentration. The combination ofthe two methods allows us to explore the correlation between galaxies shapes (smooth, with spiral arms, etc.) and their stellar contents (old or young population). The preliminary results, presented in this work, show how this new data set opens a new window on our understanding of the nearby universe.
We report photometric estimates of effective temperature, $T_{rm eff}$, metallicity, [Fe/H], carbonicity, [C/Fe], and absolute carbon abundances, $A{rm (C)}$, for over 700,000 stars from the Southern Photometric Local Universe Survey (S-PLUS) Data Release 2, covering a substantial fraction of the equatorial Sloan Digital Sky Survey Stripe 82. We present an analysis for two stellar populations: 1) halo main-sequence turnoff stars and 2) K-dwarf stars of mass $0.58 < M/M_{odot} <0.75$ in the Solar Neighborhood. Application of the Stellar Photometric Index Network Explorer (SPHINX) to the mixed-bandwidth (narrow- plus wide-band) filter photometry from S-PLUS produces robust estimates of the metallicities and carbon abundances in stellar atmospheres over a wide range of temperature, $4250 < T_{rm eff} textrm{(K)} < 7000$. The use of multiple narrow-band S-PLUS filters enables SPHINX to achieve substantially lower levels of catastrophic failures (large offsets in metallicity estimates relative to spectroscopic determinations) than previous efforts using a single metallicity-sensitive narrow-band filter. We constrain the exponential slope of the Milky Ways K-dwarf halo metallicity distribution function (MDF), $lambda_{10, textrm{[Fe/H]}} = 0.85 pm 0.21$, over the metallicity range $-2.5 < textrm{[Fe/H]} < -1.0$; the MDF of our local-volume K-dwarf sample is well-represented by a gamma distribution with parameters $alpha=2.8$ and $beta=4.2$. S-PLUS photometry obtains absolute carbon abundances with a precision of $sim 0.35$dex for stars with $T_{rm eff} < 6500$K. We identify 364 candidate carbon-enhanced metal-poor stars, obtain assignments of these stars into the Yoon-Beers morphological groups in the $A$(C)-[Fe/H] space, and derive the CEMP frequencies.
J-PLUS is an ongoing 12-band photometric optical survey, observing thousands of square degrees of the Northern hemisphere from the dedicated JAST/T80 telescope at the Observatorio Astrofisico de Javalambre. T80Cam is a 2 sq.deg field-of-view camera mounted on this 83cm-diameter telescope, and is equipped with a unique system of filters spanning the entire optical range. This filter system is a combination of broad, medium and narrow-band filters, optimally designed to extract the rest-frame spectral features (the 3700-4000AA Balmer break region, H$delta$, Ca H+K, the G-band, the Mgb and Ca triplets) that are key to both characterize stellar types and to deliver a low-resolution photo-spectrum for each pixel of the sky observed. With a typical depth of AB $sim 21.25$ mag per band, this filter set thus allows for an indiscriminate and accurate characterization of the stellar population in our Galaxy, it provides an unprecedented 2D photo-spectral information for all resolved galaxies in the local universe, as well as accurate photo-z estimates ($Delta,zsim 0.01-0.03$) for moderately bright (up to $rsim 20$ mag) extragalactic sources. While some narrow band filters are designed for the study of particular emission features ([OII]/$lambda$3727, H$alpha$/$lambda$6563) up to $z < 0.015$, they also provide well-defined windows for the analysis of other emission lines at higher redshifts. As a result, J-PLUS has the potential to contribute to a wide range of fields in Astrophysics, both in the nearby universe (Milky Way, 2D IFU-like studies, stellar populations of nearby and moderate redshift galaxies, clusters of galaxies) and at high redshifts (ELGs at $zapprox 0.77, 2.2$ and $4.4$, QSOs, etc). With this paper, we release $sim 36$ sq.deg of J-PLUS data, containing about $1.5times 10^5$ stars and $10^5$ galaxies at $r<21$ mag.
MiniJPAS is a ~1 deg^2 imaging survey of the AEGIS field in 60 bands, performed to demonstrate the scientific potential of the upcoming JPAS survey. Full coverage of the 3800-9100 AA range with 54 narrow and 6 broad optical filters allow for extremely accurate photo-z, which applied over 1000s of deg^2 will enable new applications of the photo-z technique such as measurement of baryonic acoustic oscillations. In this paper we describe the method used to obtain the photo-z included in the publicly available miniJPAS catalogue, and characterise the photo-z performance. We build 100 AA resolution photo-spectra from the PSF-corrected forced-aperture photometry. Systematic offsets in the photometry are corrected by applying magnitude shifts obtained through iterative fitting with stellar population synthesis models. We compute photo-z with a customised version of LePhare, using a set of templates optimised for the J-PAS filter-set. We analyse the accuracy of miniJPAS photo-z and their dependence on multiple quantities using a subsample of 5,266 galaxies with spectroscopic redshifts from SDSS and DEEP, that we find to be representative of the whole r<23 miniJPAS sample. Formal uncertainties for the photo-z that are calculated with the deltachi^2 method underestimate the actual redshift errors. The odds parameter has the stronger correlation with |Dz|, and accurately reproduces the probability of a redshift outlier (|Dz|>0.03) irrespective of the magnitude, redshift, or spectral type of the sources. We show that the two main summary statistics characterising the photo-z accuracy for a population of galaxies (snmad and eta) can be predicted by the distribution of odds in such population, and use this to estimate them for the whole miniJPAS sample. At r<23 there are 17,500 galaxies/deg^2 with valid photo-z estimates, of which 4,200 are expected to have |Dz|<0.003 (abridged).
We present the VISTA-CFHT Stripe 82 (VICS82) survey: a near-infrared (J+Ks) survey covering 150 square degrees of the Sloan Digital Sky Survey (SDSS) equatorial Stripe 82 to an average depth of J=21.9 AB mag and Ks=21.4 AB mag (80% completeness limits; 5-sigma point source depths are approximately 0.5 mag brighter). VICS82 contributes to the growing legacy of multi-wavelength data in the Stripe 82 footprint. The addition of near-infrared photometry to the existing SDSS Stripe 82 coadd ugriz photometry reduces the scatter in stellar mass estimates to delta log(M_stellar)~0.3 dex for galaxies with M_stellar>10^9M_sun at z~0.5, and offers improvement compared to optical-only estimates out to z~1, with stellar masses constrained within a factor of approximately 2.5. When combined with other multi-wavelength imaging of the Stripe, including moderate-to-deep ultraviolet (GALEX), optical and mid-infrared (Spitzer IRAC) coverage, as well as tens of thousands of spectroscopic redshifts, VICS82 gives access to approximately 0.5 Gpc^3 of comoving volume. Some of the main science drivers of VICS82 include (a) measuring the stellar mass function of L^star galaxies out to z~1; (b) detecting intermediate redshift quasars at 2<z<3.5; (c) measuring the stellar mass function and baryon census of clusters of galaxies, and (d) performing optical/near-infrared-cosmic microwave background lensing cross-correlation experiments linking stellar mass to large-scale dark matter structure. Here we define and describe the survey, highlight some early science results and present the first public data release, which includes an SDSS-matched catalogue as well as the calibrated pixel data itself.
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