ABSTRACT We present photometry of images from the Wide-Field Infrared Survey Explorer (WISE) of over 400 million sources detected by the Sloan Digital Sky Survey (SDSS). We use a "forced photometry" ...technique, using measured SDSS source positions, star-galaxy classification, and galaxy profiles to define the sources whose fluxes are to be measured in the WISE images. We perform photometry with The Tractor image modeling code, working on our "unWISE" coaddds and taking account of the WISE point-spread function and a noise model. The result is a measurement of the flux of each SDSS source in each WISE band. Many sources have little flux in the WISE bands, so often the measurements we report are consistent with zero given our uncertainties. However, for many sources we get 3 or 4 measurements; these sources would not be reported by the "official" WISE pipeline and will not appear in the WISE catalog, yet they can be highly informative for some scientific questions. In addition, these small-signal measurements can be used in stacking analyses at the catalog level. The forced photometry approach has the advantage that we measure a consistent set of sources between SDSS and WISE, taking advantage of the resolution and depth of the SDSS images to interpret the WISE images; objects that are resolved in SDSS but blended together in WISE still have accurate measurements in our photometry. Our results, and the code used to produce them, are publicly available at http://unwise.me.
We present an anisotropic analysis of the baryon acoustic oscillation (BAO) scale in the twelfth and final data release of the Baryon Oscillation Spectroscopic Survey (BOSS). We independently analyse ...the LOWZ and CMASS galaxy samples: the LOWZ sample contains 361 762 galaxies with an effective redshift of z
LOWZ = 0.32; the CMASS sample consists of 777 202 galaxies with an effective redshift of z
CMASS = 0.57. We extract the BAO peak position from the monopole power-spectrum moment, α0, and from the μ2 moment, α2, where μ is the cosine of the angle to the line of sight. The μ2-moment provides equivalent information to that available in the quadrupole but is simpler to analyse. After applying a reconstruction algorithm to reduce the BAO suppression by bulk motions, we measure the BAO peak position in the monopole and μ2-moment, which are related to radial and angular shifts in scale. We report H(z
LOWZ)r
s(z
d) = (11.60 ± 0.60) × 103 km s−1 and D
A(z
LOWZ)/r
s(z
d) = 6.66 ± 0.16 with a cross-correlation coefficient of
$r_{HD_{\rm A}}=0.41$
, for the LOWZ sample; and H(z
CMASS)r
s(z
d) = (14.56 ± 0.37) × 103 km s−1 and D
A(z
CMASS)/r
s(z
d) = 9.42 ± 0.13 with a cross-correlation coefficient of
$r_{HD_{\rm A}}=0.47$
, for the CMASS sample. We demonstrate that our results are not affected by the fiducial cosmology assumed for the analysis. We combine these results with the measurements of the BAO peak position in the monopole and quadrupole correlation function of the same data set (Cuesta et al. 2016, companion paper) and report the consensus values: H(z
LOWZ)r
s(z
d) = (11.63 ± 0.69) × 103 km s−1 and D
A(z
LOWZ)/r
s(z
d) = 6.67 ± 0.15 with
$r_{HD_{\rm A}}=0.35$
for the LOWZ sample; H(z
CMASS)r
s(z
d) = (14.67 ± 0.42) × 103 km s−1 and D
A(z
CMASS)/r
s(z
d) = 9.47 ± 0.12 with
$r_{HD_{\rm A}}=0.52$
for the CMASS sample.
We explore the cosmological implications of the angle-averaged correlation function, ...(s), and the clustering wedges, ...(s) and ...(s), of the LOWZ and CMASS galaxy samples from Data Releases 10 ...and 11 of the Sloan Digital Sky Survey III (SDSS-III) Baryon Oscillation Spectroscopic Survey. Our results show no significant evidence for a deviation from the standard ... cold dark matter model. The combination of the information from our clustering measurements with recent data from the cosmic microwave background is sufficient to constrain the curvature of the Universe to ...k = 0.0010 ± 0.0029, the total neutrino mass to ... < 0.23 eV (95 per cent confidence level), the effective number of relativistic species to Neff = 3.31 ± 0.27 and the dark energy equation of state to wDE = -1.051 ± 0.076. These limits are further improved by adding information from Type Ia supernovae and baryon acoustic oscillations from other samples. In particular, this data set combination is completely consistent with a time-independent dark energy equation of state, in which case we find wDE = -1.024 ± 0.052. We explore the constraints on the growth rate of cosmic structures assuming f(z) = ... and obtain ... = 0.69 ± 0.15, consistent with the predictions of general relativity of ... = 0.55. (ProQuest: ... denotes formulae/symbols omitted.)
ABSTRACT Mapping Nearby Galaxies at Apache Point Observatory (MaNGA), one of three core programs in the Sloan Digital Sky Survey-IV, is an integral-field spectroscopic survey of roughly 10,000 nearby ...galaxies. It employs dithered observations using 17 hexagonal bundles of 2″ fibers to obtain resolved spectroscopy over a wide wavelength range of 3600-10300 . To map the internal variations within each galaxy, we need to perform accurate spectral surface photometry, which is to calibrate the specific intensity at every spatial location sampled by each individual aperture element of the integral field unit. The calibration must correct only for the flux loss due to atmospheric throughput and the instrument response, but not for losses due to the finite geometry of the fiber aperture. This requires the use of standard star measurements to strictly separate these two flux loss factors (throughput versus geometry), a difficult challenge with standard single-fiber spectroscopy techniques due to various practical limitations. Therefore, we developed a technique for spectral surface photometry using multiple small fiber-bundles targeting standard stars simultaneously with galaxy observations. We discuss the principles of our approach and how they compare to previous efforts, and we demonstrate the precision and accuracy achieved. MaNGA's relative calibration between the wavelengths of H and Hβ has an rms of 1.7%, while that between N ii λ6583 and O ii λ3727 has an rms of 4.7%. Using extinction-corrected star formation rates and gas-phase metallicities as an illustration, this level of precision guarantees that flux calibration errors will be sub-dominant when estimating these quantities. The absolute calibration is better than 5% for more than 89% of MaNGA's wavelength range.
ABSTRACT The Near Earth Object Wide-field Infrared Survey Explorer (NEOWISE) Reactivation mission released data from its first full year of observations in 2015. This data set includes ∼2.5 million ...exposures in each of W1 and W2, effectively doubling the amount of WISE imaging available at 3.4 m and 4.6 m relative to the AllWISE release. We have created the first ever full-sky set of coadds combining all publicly available W1 and W2 exposures from both the AllWISE and NEOWISE-Reactivation (NEOWISER) mission phases. We employ an adaptation of the unWISE image coaddition framework, which preserves the native WISE angular resolution and is optimized for forced photometry. By incorporating two additional scans of the entire sky, we not only improve the W1/W2 depths, but also largely eliminate time-dependent artifacts such as off-axis scattered moonlight. We anticipate that our new coadds will have a broad range of applications, including target selection for upcoming spectroscopic cosmology surveys, identification of distant/massive galaxy clusters, and discovery of high-redshift quasars. In particular, our full-depth AllWISE+NEOWISER coadds will be an important input for the Dark Energy Spectroscopic Instrument selection of luminous red galaxy and quasar targets. Our full-depth W1/W2 coadds are already in use within the DECam Legacy Survey (DECaLS) and Mayall z-band Legacy Survey (MzLS) reduction pipelines. Much more work still remains in order to fully leverage NEOWISER imaging for astrophysical applications beyond the solar system.
The CatWISE2020 Catalog Marocco, Federico; Eisenhardt, Peter R. M.; Fowler, John W. ...
The Astrophysical journal. Supplement series,
03/2021, Letnik:
253, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Abstract
The CatWISE2020 Catalog consists of 1,890,715,640 sources over the entire sky selected from Wide-field Infrared Survey Explorer (WISE) and NEOWISE survey data at 3.4 and 4.6
μ
m (W1 and W2) ...collected from 2010 January 7 to 2018 December 13. This data set adds two years to that used for the CatWISE Preliminary Catalog, bringing the total to six times as many exposures spanning over 16 times as large a time baseline as the AllWISE catalog. The other major change from the CatWISE Preliminary Catalog is that the detection list for the CatWISE2020 Catalog was generated using
crowdsource
from Schlafly et al., while the CatWISE Preliminary Catalog used the detection software used for AllWISE. These two factors result in roughly twice as many sources in the CatWISE2020 Catalog. The scatter with respect to Spitzer photometry at faint magnitudes in the COSMOS field, which is out of the Galactic Plane and at low ecliptic latitude (corresponding to lower WISE coverage depth) is similar to that for the CatWISE Preliminary Catalog. The 90% completeness depth for the CatWISE2020 Catalog is at W1 = 17.7 mag and W2 = 17.5 mag, 1.7 mag deeper than in the CatWISE Preliminary Catalog. In comparison to Gaia, CatWISE2020 motions are accurate at the 20 mas yr
−1
level for W1∼15 mag sources and at the ∼100 mas yr
−1
level for W1∼17 mag sources. This level of accuracy represents a 12× improvement over AllWISE. The CatWISE catalogs are available in the WISE/NEOWISE Enhanced and Contributed Products area of the NASA/IPAC Infrared Science Archive.
We examine the relationship between environment and the luminosities, surface brightnesses, colors, and profile shapes of luminous galaxies in the Sloan Digital Sky Survey (SDSS). For the SDSS ...sample, galaxy color is the galaxy property most predictive of the local environment. Galaxy color and luminosity--measures of the star formation history--jointly comprise the most predictive pair of properties. At fixed luminosity and color, density is not closely related to surface brightness or to Sersic index--measures of galaxy structure. In the text, we discuss what measurable residual relationships exist, generally finding that at red colors and fixed luminosity, the mean density decreases at the highest surface brightnesses and Sersic indices. In general, these results suggest that the structural properties of galaxies are less closely related to galaxy environment than are their masses and star formation histories.
We measure and analyse the clustering of the Baryon Oscillation Spectroscopic Survey (BOSS) relative to the line of sight (LOS), for LOWZ and CMASS galaxy samples drawn from the final Data Release ...12. The LOWZ sample contains 361 762 galaxies with an effective redshift of z
lowz = 0.32, and the CMASS sample 777 202 galaxies with an effective redshift of z
cmass = 0.57. From the power spectrum monopole and quadrupole moments around the LOS, we measure the growth of structure parameter f times the amplitude of dark matter density fluctuations σ8 by modelling the redshift-space distortion signal. When the geometrical Alcock–Paczynski effect is also constrained from the same data, we find joint constraints on fσ8, the product of the Hubble constant and the comoving sound horizon at the baryon-drag epoch H(z)r
s(z
d), and the angular distance parameter divided by the sound horizon D
A(z)/r
s(z
d). We find f(z
lowz)σ8(z
lowz) = 0.394 ± 0.062, D
A(z
lowz)/r
s(z
d) = 6.35 ± 0.19, H(z
lowz)r
s(z
d) = (11.41 ± 0.56) 103 km s− 1 for the LOWZ sample, and f(z
cmass)σ8(z
cmass) = 0.444 ± 0.038, D
A(z
cmass)/r
s(z
d) = 9.42 ± 0.15, H(z
cmass)r
s(z
d) = (13.92 ± 0.44) 103 km s− 1 for the CMASS sample. We find general agreement with previous BOSS DR11 measurements. Assuming the Hubble parameter and angular distance parameter are fixed at fiducial Λcold dark matter values, we find f(z
lowz)σ8(z
lowz) = 0.485 ± 0.044 and f(z
cmass)σ8(z
cmass) = 0.436 ± 0.022 for the LOWZ and CMASS samples, respectively.
We utilize Sloan Digital Sky Survey imaging and spectroscopy of 653,000 star-forming galaxies at z60.1 to study the relation between stellar mass and gas-phase metallicity. We derive gas-phase oxygen ...abundances and stellar masses using new techniques that make use of the latest stellar evolutionary synthesis and photoionization models. We find a tight (c0.1 dex) correlation between stellar mass and metallicity spanning over 3 orders of magnitude in stellar mass and a factor of 10 in metallicity. The relation is relatively steep from 10 super(8.5) to 10 super(10.5) M sub( )h70 super(-2), in good accord with known trends between luminosity and metallicity, but flattens above 10 super(10.5) M sub( ). We use indirect estimates of the gas mass based on the Ha luminosity to compare our data to predictions from simple closed box chemical evolution models. We show that metal loss is strongly anticorrelated with baryonic mass, with low-mass dwarf galaxies being 5 times more metal depleted than L* galaxies at z60.1. Evidence for metal depletion is not confined to dwarf galaxies but is found in galaxies with masses as high as 10 super(10) M sub( ). We interpret this as strong evidence of both the ubiquity of galactic winds and their effectiveness in removing metals from galaxy potential wells.
ABSTRACT As part of the Sloan Digital Sky Survey (SDSS) IV the extended Baryon Oscillation Spectroscopic Survey (eBOSS) will improve measurements of the cosmological distance scale by applying the ...Baryon Acoustic Oscillation (BAO) method to quasar samples. eBOSS will adopt two approaches to target quasars over 7500 deg2. First, a "CORE" quasar sample will combine the optical selection in ugriz using a likelihood-based routine called XDQSOz, with a mid-IR-optical color cut. eBOSS CORE selection (to g < 22 or r < 22) should return ∼70 deg−2 quasars at redshifts 0.9 < z < 2.2 and ∼7 deg−2z > 2.1 quasars. Second, a selection based on variability in multi-epoch imaging from the Palomar Transient Factory should recover an additional ∼3-4 deg−2z > 2.1 quasars to g < 22.5. A linear model of how imaging systematics affect target density recovers the angular distribution of eBOSS CORE quasars over 96.7% (76.7%) of the SDSS north (south) Galactic Cap area. The eBOSS CORE quasar sample should thus be sufficiently dense and homogeneous over 0.9 < z < 2.2 to yield the first few-percent-level BAO constraint near eBOSS quasars at z > 2.1 will be used to improve BAO measurements in the Ly Forest. Beyond its key cosmological goals, eBOSS should be the next-generation quasar survey, comprising >500,000 new quasars and >500,000 uniformly selected spectroscopically confirmed 0.9 < z < 2.2 quasars. At the conclusion of eBOSS, the SDSS will have provided unique spectra for more than 800,000 quasars.
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