Characterizing the target selection pipeline for the Dark Energy Spectroscopic Instrument Bright Galaxy Survey

ABSTRACT We present the steps taken to produce a reliable and complete input galaxy catalogue for the Dark Energy Spectroscopic Instrument (DESI) Bright Galaxy Survey (BGS) using the photometric Legacy Survey DR8 DECam. We analyse some of the main issues faced in the selection of targets for the DESI BGS, such as star–galaxy separation, contamination by fragmented stars and bright galaxies. Our pipeline utilizes a new way to select BGS galaxies using Gaia photometry and we implement geometrical and photometric masks that reduce the number of spurious objects. The resulting catalogue is cross-matched with the Galaxy And Mass Assembly (GAMA) survey to assess the completeness of the galaxy catalogue and the performance of the target selection. We also validate the clustering of the sources in our BGS catalogue by comparing with mock catalogues and the Sloan Digital Sky Survey (SDSS) data. Finally, the robustness of the BGS selection criteria is assessed by quantifying the dependence of the target galaxy density on imaging and other properties. The largest systematic correlation we find is a 7 per cent suppression of the target density in regions of high stellar density.

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Searching for Mg ii absorbers in and around galaxy clusters

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab637 ◽

2021 ◽

Vol 503 (3) ◽

pp. 4309-4319

Author(s):

Jong Chul Lee ◽

Ho Seong Hwang ◽

Hyunmi Song

Keyword(s):

Galaxy Clusters ◽

Detection Rate ◽

Massive Star ◽

Sloan Digital Sky Survey ◽

Number Density ◽

Cluster Galaxies ◽

Star Forming ◽

Quasar Spectra ◽

Sky Survey ◽

The Galaxy

ABSTRACT To study environmental effects on the circumgalactic medium (CGM), we use the samples of redMaPPer galaxy clusters, background quasars, and cluster galaxies from the Sloan Digital Sky Survey (SDSS). With ∼82 000 quasar spectra, we detect 197 Mg ii absorbers in and around the clusters. The detection rate per quasar is 2.7 ± 0.7 times higher inside the clusters than outside the clusters, indicating that Mg ii absorbers are relatively abundant in clusters. However, when considering the galaxy number density, the absorber-to-galaxy ratio is rather low inside the clusters. If we assume that Mg ii absorbers are mainly contributed by the CGM of massive star-forming galaxies, a typical halo size of cluster galaxies is smaller than that of field galaxies by 30 ± 10 per cent. This finding supports that galaxy haloes can be truncated by interaction with the host cluster.

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Surface Photometry of Spiral Galaxy NGC 5005 and Elliptical Galaxy NGC 4278

Baghdad Science Journal ◽

10.21123/bsj.15.3.314-323 ◽

2018 ◽

Vol 15 (3) ◽

pp. 314-323

Author(s):

Baghdad Science Journal

Keyword(s):

Spiral Galaxy ◽

Surface Brightness ◽

Elliptical Galaxy ◽

Position Angle ◽

Sloan Digital Sky Survey ◽

Surface Photometry ◽

Contour Maps ◽

Sky Survey ◽

Flat Field ◽

The Galaxy

Two galaxies have been chosen, spiral galaxy NGC 5005 and elliptical galaxy NGC 4278 to study their photometric properties by using surface photometric techniques with griz-Filters. Observations are obtained from the Sloan Digital Sky Survey (SDSS). The data reduction of all images have done, like bias and flat field, by SDSS pipeline. The overall structure of the two galaxies (a bulge, a disk), together with isophotal contour maps, surface brightness profiles and a bulge/disk decomposition of the galaxy images were performed, although the disk position angle, ellipticity and inclination of the galaxies have been estimated.

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A study on the statistical significance of mutual information between morphology of a galaxy and its large-scale environment

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2236 ◽

2020 ◽

Vol 497 (4) ◽

pp. 4077-4090 ◽

Cited By ~ 1

Author(s):

Suman Sarkar ◽

Biswajit Pandey

Keyword(s):

Mutual Information ◽

Large Scale ◽

Statistical Significance ◽

Sloan Digital Sky Survey ◽

Data Sets ◽

Information Theoretic ◽

Galaxy Distribution ◽

Sky Survey ◽

The Galaxy ◽

Physical Correlations

ABSTRACT A non-zero mutual information between morphology of a galaxy and its large-scale environment is known to exist in Sloan Digital Sky Survey (SDSS) upto a few tens of Mpc. It is important to test the statistical significance of these mutual information if any. We propose three different methods to test the statistical significance of these non-zero mutual information and apply them to SDSS and Millennium run simulation. We randomize the morphological information of SDSS galaxies without affecting their spatial distribution and compare the mutual information in the original and randomized data sets. We also divide the galaxy distribution into smaller subcubes and randomly shuffle them many times keeping the morphological information of galaxies intact. We compare the mutual information in the original SDSS data and its shuffled realizations for different shuffling lengths. Using a t-test, we find that a small but statistically significant (at $99.9{{\ \rm per\ cent}}$ confidence level) mutual information between morphology and environment exists upto the entire length-scale probed. We also conduct another experiment using mock data sets from a semi-analytic galaxy catalogue where we assign morphology to galaxies in a controlled manner based on the density at their locations. The experiment clearly demonstrates that mutual information can effectively capture the physical correlations between morphology and environment. Our analysis suggests that physical association between morphology and environment may extend to much larger length-scales than currently believed, and the information theoretic framework presented here can serve as a sensitive and useful probe of the assembly bias and large-scale environmental dependence of galaxy properties.

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Redshift measurement through star formation

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833046 ◽

2019 ◽

Vol 629 ◽

pp. A7

Author(s):

Mikkel O. Lindholmer ◽

Kevin A. Pimbblet

Keyword(s):

Star Formation ◽

Galaxy Clusters ◽

Main Sequence ◽

Formation Rate ◽

Sloan Digital Sky Survey ◽

X Ray ◽

Star Forming ◽

Sky Survey ◽

The Galaxy ◽

Galaxy Population

In this work we use the property that, on average, star formation rate increases with redshift for objects with the same mass – the so called galaxy main sequence – to measure the redshift of galaxy clusters. We use the fact that the general galaxy population forms both a quenched and a star-forming sequence, and we locate these ridges in the SFR–M⋆ plane with galaxies taken from the Sloan Digital Sky Survey in discrete redshift bins. We fitted the evolution of the galaxy main sequence with redshift using a new method and then subsequently apply our method to a suite of X-ray selected galaxy clusters in an attempt to create a new distance measurement to clusters based on their galaxy main sequence. We demonstrate that although it is possible in several galaxy clusters to measure the main sequences, the derived distance and redshift from our galaxy main sequence fitting technique has an accuracy of σz = ±0.017 ⋅ (z + 1) and is only accurate up to z ≈ 0.2.

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Efficient Photometric Selection of Quasars from the Sloan Digital Sky Survey: 100,000 z < 3 Quasars from Data Release One

The Astrophysical Journal Supplement Series ◽

10.1086/425356 ◽

2004 ◽

Vol 155 (2) ◽

pp. 257-269 ◽

Cited By ~ 157

Author(s):

Gordon T. Richards ◽

Robert C. Nichol ◽

Alexander G. Gray ◽

Robert J. Brunner ◽

Robert H. Lupton ◽

...

Keyword(s):

Sloan Digital Sky Survey ◽

Sky Survey ◽

Data Release ◽

Selection Of

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The Ursa Major Cluster Redefined as a ‘Supergroup’

Publications of the Astronomical Society of Australia ◽

10.1017/pasa.2016.31 ◽

2016 ◽

Vol 33 ◽

Cited By ~ 5

Author(s):

K. Wolfinger ◽

V. A. Kilborn ◽

E. V. Ryan-Weber ◽

B. S. Koribalski

Keyword(s):

Real Data ◽

Virgo Cluster ◽

Sloan Digital Sky Survey ◽

Galaxy Groups ◽

The Third ◽

Evolutionary State ◽

Sky Survey ◽

Major Cluster ◽

The Galaxy ◽

Major Region

AbstractWe identify gravitationally bound structures in the Ursa Major region using positions, velocities and photometry from the Sloan Digital Sky Survey (SDSS DR7) and the Third Reference Catalogue of Bright Galaxies (RC3). A friends-of-friends algorithm is extensively tested on mock galaxy lightcones and then implemented on the real data to determine galaxy groups whose members are likely to be physically and dynamically associated with one another. We find several galaxy groups within the region that are likely bound to one another and in the process of merging. We classify 6 galaxy groups as the Ursa Major ‘supergroup’, which are likely to merge and form a poor cluster with a mass of ~ 8 × 1013 M⊙. Furthermore, the Ursa Major supergroup as a whole is likely bound to the Virgo cluster, which will eventually form an even larger system in the context of hierarchical structure formation. We investigate the evolutionary state of the galaxy groups in the Ursa Major region and conclude that these groups are in an early evolutionary state and the properties of their member galaxies are similar to those in the field.

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Finding and characterising WHIM structures using the luminosity density method

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316010188 ◽

2014 ◽

Vol 11 (S308) ◽

pp. 368-371

Author(s):

Jukka Nevalainen ◽

L. J. Liivamägi ◽

E. Tempel ◽

E. Branchini ◽

M. Roncarelli ◽

...

Keyword(s):

Large Scale ◽

Real Data ◽

Sloan Digital Sky Survey ◽

Physical Parameters ◽

X Ray ◽

Galaxy Surveys ◽

Sky Survey ◽

The Galaxy ◽

Hydrodynamical Simulations ◽

X Ray Absorption

AbstractWe have developed a new method to approach the missing baryons problem. We assume that the missing baryons reside in a form of Warm Hot Intergalactic Medium, i.e. the WHIM. Our method consists of (a) detecting the coherent large scale structure in the spatial distribution of galaxies that traces the Cosmic Web and that in hydrodynamical simulations is associated to the WHIM, (b) mapping its luminosity into a galaxy luminosity density field, (c) using numerical simulations to relate the luminosity density to the density of the WHIM, (d) applying this relation to real data to trace the WHIM using the observed galaxy luminosities in the Sloan Digital Sky Survey and 2dF redshift surveys. In our application we find evidence for the WHIM along the line of sight to the Sculptor Wall, at redshifts consistent with the recently reported X-ray absorption line detections. Our indirect WHIM detection technique complements the standard method based on the detection of characteristic X-ray absorption lines, showing that the galaxy luminosity density is a reliable signpost for the WHIM. For this reason, our method could be applied to current galaxy surveys to optimise the observational strategies for detecting and studying the WHIM and its properties. Our estimates of the WHIM hydrogen column density NH in Sculptor agree with those obtained via the X-ray analysis. Due to the additional NH estimate, our method has potential for improving the constrains of the physical parameters of the WHIM as derived with X-ray absorption, and thus for improving the understanding of the missing baryons problem.

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Candidate Periodically Variable Quasars from the Dark Energy Survey and the Sloan Digital Sky Survey

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2957 ◽

2020 ◽

Author(s):

Yu-Ching Chen ◽

Xin Liu ◽

Wei-Ting Liao ◽

A Miguel Holgado ◽

Hengxiao Guo ◽

...

Keyword(s):

Black Holes ◽

Dark Energy ◽

Detection Rate ◽

Sloan Digital Sky Survey ◽

Light Curves ◽

Close Binary ◽

Single Frequency ◽

Dark Energy Survey ◽

Sky Survey ◽

Energy Survey

Abstract Periodically variable quasars have been suggested as close binary supermassive black holes. We present a systematic search for periodic light curves in 625 spectroscopically confirmed quasars with a median redshift of 1.8 in a 4.6 deg2 overlapping region of the Dark Energy Survey Supernova (DES-SN) fields and the Sloan Digital Sky Survey Stripe 82 (SDSS-S82). Our sample has a unique 20-year long multi-color (griz) light curve enabled by combining DES-SN Y6 observations with archival SDSS-S82 data. The deep imaging allows us to search for periodic light curves in less luminous quasars (down to r ∼23.5 mag) powered by less massive black holes (with masses ≳ 108.5M⊙) at high redshift for the first time. We find five candidates with significant (at >99.74% single-frequency significance in at least two bands with a global p-value of ∼7 × 10−4–3× 10−3 accounting for the look-elsewhere effect) periodicity with observed periods of ∼3–5 years (i.e., 1–2 years in rest frame) having ∼4–6 cycles spanned by the observations. If all five candidates are periodically variable quasars, this translates into a detection rate of ${\sim }0.8^{+0.5}_{-0.3}$% or ${\sim }1.1^{+0.7}_{-0.5}$ quasar per deg2. Our detection rate is 4–80 times larger than those found by previous searches using shallower surveys over larger areas. This discrepancy is likely caused by differences in the quasar populations probed and the survey data qualities. We discuss implications on the future direct detection of low-frequency gravitational waves. Continued photometric monitoring will further assess the robustness and characteristics of these candidate periodic quasars to determine their physical origins.

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Revealing galactic scale bars with the help of Galaxy Zoo

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314005882 ◽

2012 ◽

Vol 10 (H16) ◽

pp. 324-324

Author(s):

Karen L. Masters ◽

Keyword(s):

Stellar Mass ◽

Sloan Digital Sky Survey ◽

Gas Content ◽

Barred Galaxies ◽

Sky Survey ◽

The Galaxy ◽

Galaxy Sample ◽

External Sources ◽

Disc Galaxies ◽

Environmental Dependence

AbstractWe use visual classifications of the brightest 250,000 galaxies in the Sloan Digital Sky Survey Main Galaxy Sample provided by citizen scientists via the Galaxy Zoo project (www.galaxyzoo.org, Lintott et al. 2008) to identify a sample of local disc galaxies with reliable bar identifications.These data, combined with information on the atomic gas content from the ALFALFA survey (Haynes et al. 2011) show that disc galaxies with higher gas content have lower bar fractions.We use a gas deficiency parameter to show that disc galaxies with more/less gas than expected for their stellar mass are less/more likely to host bars. Furthermore, we see that at a fixed gas content there is no residual correlation between bar fraction and stellar mass. We argue that this suggests previously observed correlations between galaxy colour/stellar mass and (strong) bar fraction (e.g. from the sample in Masters et al. 2011, and also see Nair & Abraham 2010) could be driven by the interaction between bars and the gas content of the disc, since more massive, optically redder disc galaxies are observed to have lower gas contents.Furthermore we see evidence that at a fixed gas content the global colours of barred galaxies are redder than those of unbarred galaxies. We suggest that this could be due to the exchange of angular momentum beyond co-rotation which might stop a replenishment of gas from external sources, and act as a source of feedback to temporarily halt or reduce the star formation in the outer parts of barred discs.These results (published as Masters et al. 2012) combined with those of Skibba et al. (2012), who use the same sample to show a clear (but subtle and complicated) environmental dependence of the bar fraction in disc galaxies, suggest that bars are intimately linked to the evolution of disc galaxies.

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