Weak Lensing with Sloan Digital Sky Survey Commissioning Data: The Galaxy-Mass Correlation Function to 1 [CLC][ITAL]h[/ITAL][/CLC][TSUP]−1[/TSUP] M[CLC]pc[/CLC]

We directly constrain the non-linear alignment (NLA) model of intrinsic galaxy alignments, analysing the most representative and complete flux-limited sample of spectroscopic galaxies available for cosmic shear surveys. We measure the projected galaxy position-intrinsic shear correlations and the projected galaxy clustering signal using high-resolution imaging from the Kilo Degree Survey (KiDS) overlapping with the GAMA spectroscopic survey, and data from the Sloan Digital Sky Survey. Separating samples by colour, we make no significant detection of blue galaxy alignments, constraining the blue galaxy NLA amplitude AIAB = 0.21−0.36+0.37 to be consistent with zero. We make robust detections (∼9σ) for red galaxies, with AIAR = 3.18−0.46+0.47, corresponding to a net radial alignment with the galaxy density field, and we find no evidence for any scaling of alignments with galaxy luminosity. We provide informative priors for current and future weak lensing surveys, an improvement over de facto wide priors that allow for unrealistic levels of intrinsic alignment contamination. For a colour-split cosmic shear analysis of the final KiDS survey area, we forecast that our priors will improve the constraining power on S8 and the dark energy equation of state w0, by up to 62% and 51%, respectively. Our results indicate, however, that the modelling of red/blue-split galaxy alignments may be insufficient to describe samples with variable central/satellite galaxy fractions.

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Information Content in the Galaxy Angular Power Spectrum from the Sloan Digital Sky Survey and Its Implication on Weak-Lensing Analysis

The Astrophysical Journal ◽

10.1086/592820 ◽

2008 ◽

Vol 686 (1) ◽

pp. L1-L4 ◽

Cited By ~ 31

Author(s):

Jounghun Lee ◽

Ue-Li Pen

Keyword(s):

Power Spectrum ◽

Information Content ◽

Sloan Digital Sky Survey ◽

Weak Lensing ◽

Angular Power Spectrum ◽

Sky Survey ◽

The Galaxy

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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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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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