Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant Universe

We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and. high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median z similar to 0.03). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between z similar to 0.6 and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs. and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the. Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July.

NEAR-ULTRAVIOLET SPECTROSCOPY OF STAR-FORMING GALAXIES FROM eBOSS: SIGNATURES OF UBIQUITOUS GALACTIC-SCALE OUTFLOWS

Johan Comparat, Timothée Guy Olivier Delubac, Jean-Paul Richard Kneib, Jeffrey Newman, Anand Stéphane Raichoor

We present rest-frame near-ultraviolet (NUV) spectroscopy of star-forming galaxies (SFGs) at 0.6 < z < 1.2 from the Extended Baryon Oscillation Spectroscopic Survey (eBOSS) in SDSS-IV. One of the eBOSS programs is to obtain 2 ''. (about 15 kpc) fiber spectra of about 200,000 emission-line galaxies (ELGs) at redshift z greater than or similar to 0.6. We use the data from the pilot observations of this program, including 8620 spectra of SFGs at 0.6 < z < 1.2. The median composite spectra of these SFGs at 2200 angstrom < lambda < 4000 angstrom feature asymmetric, preferentially blueshifted non-resonant emission, Fe II*, and blueshifted resonant absorption, e.g., Fe II and Mg II, indicating ubiquitous outflows driven by star formation at these redshifts. For the absorption lines, we find a variety of velocity profiles with different degrees of blueshift. Comparing our new observations with the literature, we do not observe the non-resonant emission in the small-aperture (< 40 pc) spectra of local star-forming regions with the Hubble Space Telescope, and find the observed line ratios in the SFG spectra to be different from those in the spectra of local star-forming regions, as well as those of quasar absorption-line systems in the same redshift range. We introduce an outflow model that can simultaneously explain the multiple observed properties and suggest that the variety of absorption velocity profiles and the line ratio differences are caused by scattered fluorescent emission filling in on top of the absorption in the large-aperture eBOSS spectra. We develop an observation-driven, model-independent method to correct the emission infill to reveal the true absorption profiles. Finally, we show that the strengths of both the non-resonant emission and the emission-corrected resonant absorption increase with [O II] lambda lambda 3727, 3730 rest equivalent width and luminosity, with a slightly larger dependence on the former. Our results show that the eBOSS and future dark-energy surveys (e.g., Dark Energy Spectroscopic Instrument survey and Prime Focus Spectrograph survey) will provide rich data sets of rest-frame NUV spectroscopy for astrophysical applications.

Iop Publishing Ltd2015

VICS82: The VISTA-CFHT Stripe 82 Near-infrared Survey

Johan Comparat, Jean-Paul Richard Kneib

We present the VISTA-CFHT Stripe 82 (VICS82) survey: a near-infrared (J+K-s) 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 K-s = 21.4 AB mag (80% completeness limits; 5s point-source depths are approximately 0.5 mag brighter). VICS82 contributes to the growing legacy of multiwavelength 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 d log(M-star) approximate to 0.3 dex for galaxies withM 109 M-star > 10(9) at z approximate to 0.5, and offers improvement compared to optical-only estimates out to z similar to 1, with stellar masses constrained within a factor of approximately 2.5. When combined with other multiwavelength 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 similar to 1; (b) detecting intermediate-redshift quasars at 2 less than or similar to z less than or similar to 3.5; (c) measuring the stellar mass function and baryon census of clusters of galaxies, and (d) performing cross-correlation experiments of cosmic microwave background lensing in the. optical/near-infrared that. link. 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 catalog as well as the calibrated pixel data themselves.

Iop Publishing Ltd2017

The 13th Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-IV Survey Mapping Nearby Galaxies at Apache Point Observatory

Guillaume Blanc, Yuguang Chen, Johan Comparat, Timothée Guy Olivier Delubac, Ginevra Favole, Yang Gao, Amy Jones, Jean-Paul Richard Kneib, Pierre Laurent, Chen Li, Cheng Li, Yu Liang, Chao Liu, Anand Stéphane Raichoor, David Schlegel, Michael James Henry Smith, Yuting Wang, John Wilson, Meng Yang, Kai Zhang, Cheng Zhao, Zheng Zheng

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) began observations in 2014 July. It pursues three core programs: the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2), Mapping Nearby Galaxies at APO (MaNGA), and the Extended Baryon Oscillation Spectroscopic Survey (eBOSS). As well as its core program, eBOSS contains two major subprograms: the Time Domain Spectroscopic Survey (TDSS) and the SPectroscopic IDentification of ERosita Sources (SPIDERS). This paper describes the first data release from SDSS-IV, Data Release 13 (DR13). DR13 makes publicly available the first 1390 spatially resolved integral field unit observations of nearby galaxies from MaNGA. It includes new observations from eBOSS, completing the Sloan Extended QUasar, Emission-line galaxy, Luminous red galaxy Survey (SEQUELS), which also targeted variability-selected objects and X-ray-selected objects. DR13 includes new reductions of the SDSS-III BOSS data, improving the spectrophotometric calibration and redshift classification, and new reductions of the SDSS-III APOGEE-1 data, improving stellar parameters for dwarf stars and cooler stars. DR13 provides more robust and precise photometric calibrations. Value-added target catalogs relevant for eBOSS, TDSS, and SPIDERS and an updated red-clump catalog for APOGEE are also available. This paper describes the location and format of the data and provides references to important technical papers. The SDSS web site, http://www.sdss.org, provides links to the data, tutorials, examples of data access, and extensive documentation of the reduction and analysis procedures. DR13 is the first of a scheduled set that will contain new data and analyses from the planned similar to 6 yr operations of SDSS-IV.

Iop Publishing Ltd2017

NEAR-ULTRAVIOLET SPECTROSCOPY OF STAR-FORMING GALAXIES FROM eBOSS: SIGNATURES OF UBIQUITOUS GALACTIC-SCALE OUTFLOWS

Johan Comparat, Timothée Guy Olivier Delubac, Jean-Paul Richard Kneib, Jeffrey Newman, Anand Stéphane Raichoor

Iop Publishing Ltd2015

The 13th Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-IV Survey Mapping Nearby Galaxies at Apache Point Observatory

Iop Publishing Ltd2017