scholarly journals KiDS+GAMA: Intrinsic alignment model constraints for current and future weak lensing cosmology

2019 ◽  
Vol 624 ◽  
pp. A30 ◽  
Author(s):  
Harry Johnston ◽  
Christos Georgiou ◽  
Benjamin Joachimi ◽  
Henk Hoekstra ◽  
Nora Elisa Chisari ◽  
...  
Keyword(s):  
Sloan Digital Sky Survey ◽  
Weak Lensing ◽  
Satellite Galaxy ◽  
Sky Survey ◽  
The Galaxy ◽  
Resolution Imaging ◽  
Cosmic Shear ◽  
Linear Alignment ◽  
Red Galaxies ◽  
Blue Galaxy

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.

scholarly journals How dark are filaments in the cosmic web?

2020 ◽  
Vol 498 (3) ◽  
pp. 3158-3170
Author(s):  
Tianyi Yang ◽  
Michael J Hudson ◽  
Niayesh Afshordi
Keyword(s):  
Dark Matter ◽  
Galaxy Formation ◽  
Cold Dark Matter ◽  
Stellar Mass ◽  
Sloan Digital Sky Survey ◽  
Weak Lensing ◽  
Sky Survey ◽  
Mass Fractions ◽  
The Masses ◽  
Red Galaxies

ABSTRACT The cold dark matter model predicts that dark matter haloes are connected by filaments. Direct measurements of the masses and structure of these filaments are difficult, but recently several studies have detected these dark-matter-dominated filaments using weak lensing. Here we study the efficiency of galaxy formation within the filaments by measuring their total mass-to-light ratios and stellar mass fractions. Specifically, we stack pairs of luminous red galaxies (LRGs) with a typical separation on the sky of 8 h−1 Mpc. We stack background galaxy shapes around pairs to obtain mass maps through weak lensing, and we stack galaxies from the Sloan Digital Sky Survey to obtain maps of light and stellar mass. To isolate the signal from the filament, we construct two matched catalogues of physical and non-physical (projected) LRG pairs, with the same distributions of redshift and separation. We then subtract the two stacked maps. Using LRG pair samples from the Baryon Oscillation Spectroscopic Survey at two different redshifts, we find that the evolution of the mass in filament is consistent with the predictions from perturbation theory. The filaments are not entirely dark: Their mass-to-light ratios (M/L = 351 ± 137 in solar units in the rband) and stellar mass fractions (Mstellar/M = 0.0073 ± 0.0030) are consistent with the cosmic values (and with their redshift evolutions).

scholarly journals The Galaxy-Mass Correlation Function Measured from Weak Lensing in the Sloan Digital Sky Survey

2004 ◽  
Vol 127 (5) ◽  
pp. 2544-2564 ◽  
Author(s):  
Erin S. Sheldon ◽  
David E. Johnston ◽  
Joshua A. Frieman ◽  
Ryan Scranton ◽  
Timothy A. McKay ◽  
...  
Keyword(s):  
Correlation Function ◽  
Sloan Digital Sky Survey ◽  
Weak Lensing ◽  
Sky Survey ◽  
The Galaxy

scholarly journals A gravitational lensing detection of filamentary structures connecting luminous red galaxies

2020 ◽  
Vol 633 ◽  
pp. A89 ◽  
Author(s):  
Qianli Xia ◽  
Naomi Robertson ◽  
Catherine Heymans ◽  
Alexandra Amon ◽  
Marika Asgari ◽  
...  
Keyword(s):  
Gravitational Lensing ◽  
Critical Density ◽  
Average Density ◽  
Sloan Digital Sky Survey ◽  
Weak Lensing ◽  
Luminous Red Galaxies ◽  
Sky Survey ◽  
Combining Data ◽  
Red Galaxies ◽  
Cluster Sequence

We present a weak lensing detection of filamentary structures in the cosmic web, combining data from the Kilo-Degree Survey, the Red Cluster Sequence Lensing Survey, and the Canada-France-Hawaii Telescope Lensing Survey. The line connecting luminous red galaxies with a separation of 3 − 5 h−1 Mpc was chosen as a proxy for the location of filaments. We measured the average weak lensing shear around ∼11 000 candidate filaments selected in this way from the Sloan Digital Sky Survey. After nulling the shear induced by the dark matter haloes around each galaxy, we reported a 3.4σ detection of an anisotropic shear signal from the matter that connects them. Adopting a filament density profile, motivated from N-body simulations, the average density at the centre of these filamentary structures was found to be 15 ± 4 times the critical density.

scholarly journals Exploring galaxy colour in different environments of the cosmic web with SDSS

2020 ◽  
Vol 498 (4) ◽  
pp. 6069-6082
Author(s):  
Biswajit Pandey ◽  
Suman Sarkar
Keyword(s):  
Local Density ◽  
Stellar Mass ◽  
Sloan Digital Sky Survey ◽  
Local Dimension ◽  
Sky Survey ◽  
The Galaxy ◽  
Colour Distribution ◽  
The Mean ◽  
Red Galaxies

ABSTRACT We analyse a set of volume-limited samples from the Sloan Digital Sky Survey (SDSS) to study the dependence of galaxy colour on different environments of the cosmic web. We measure the local dimension of galaxies to determine the geometry of their embedding environments and find that filaments host a higher fraction of red galaxies than sheets at each luminosity. We repeat the analysis at a fixed density and recover the same trend, which shows that galaxy colours depend on geometry of environments besides local density. At a fixed luminosity, the fraction of red galaxies in filaments and sheets increases with the extent of these environments. This suggests that the bigger structures have a larger baryon reservoir favouring higher accretion and larger stellar mass. We find that the mean colour of the red and blue populations are systematically higher in the environments with smaller local dimension and increases monotonically in all the environments with luminosity. We observe that the bimodal nature of the galaxy colour distribution persists in all environments and all luminosities, which suggests that the transformation from blue to red galaxy can occur in all environments.

scholarly journals 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]

2000 ◽  
Vol 120 (3) ◽  
pp. 1198-1208 ◽  
Author(s):  
Philippe Fischer ◽  
Timothy A. McKay ◽  
Erin Sheldon ◽  
Andrew Connolly ◽  
Albert Stebbins ◽  
...  
Keyword(s):  
Correlation Function ◽  
Sloan Digital Sky Survey ◽  
Weak Lensing ◽  
Sky Survey ◽  
The Galaxy

scholarly journals HOLISMOKES

2020 ◽  
Vol 644 ◽  
pp. A163 ◽  
Author(s):  
R. Cañameras ◽  
S. Schuldt ◽  
S. H. Suyu ◽  
S. Taubenberger ◽  
T. Meinhardt ◽  
...  
Keyword(s):  
Neural Network ◽  
Network Architecture ◽  
High Redshift ◽  
Sloan Digital Sky Survey ◽  
Spatially Resolved ◽  
Sky Survey ◽  
Central Regions ◽  
Long Time ◽  
Resolution Imaging ◽  
Red Galaxies

We present a systematic search for wide-separation (with Einstein radius θE ≳ 1.5″), galaxy-scale strong lenses in the 30 000 deg2 of the Pan-STARRS 3π survey on the Northern sky. With long time delays of a few days to weeks, these types of systems are particularly well-suited for catching strongly lensed supernovae with spatially-resolved multiple images and offer new insights on early-phase supernova spectroscopy and cosmography. We produced a set of realistic simulations by painting lensed COSMOS sources on Pan-STARRS image cutouts of lens luminous red galaxies (LRGs) with redshift and velocity dispersion known from the sloan digital sky survey (SDSS). First, we computed the photometry of mock lenses in gri bands and applied a simple catalog-level neural network to identify a sample of 1 050 207 galaxies with similar colors and magnitudes as the mocks. Second, we trained a convolutional neural network (CNN) on Pan-STARRS gri image cutouts to classify this sample and obtain sets of 105 760 and 12 382 lens candidates with scores of pCNN > 0.5 and > 0.9, respectively. Extensive tests showed that CNN performances rely heavily on the design of lens simulations and the choice of negative examples for training, but little on the network architecture. The CNN correctly classified 14 out of 16 test lenses, which are previously confirmed lens systems above the detection limit of Pan-STARRS. Finally, we visually inspected all galaxies with pCNN > 0.9 to assemble a final set of 330 high-quality newly-discovered lens candidates while recovering 23 published systems. For a subset, SDSS spectroscopy on the lens central regions proves that our method correctly identifies lens LRGs at z ∼ 0.1–0.7. Five spectra also show robust signatures of high-redshift background sources, and Pan-STARRS imaging confirms one of them as a quadruply-imaged red source at zs = 1.185, which is likely a recently quenched galaxy strongly lensed by a foreground LRG at zd = 0.3155. In the future, high-resolution imaging and spectroscopic follow-up will be required to validate Pan-STARRS lens candidates and derive strong lensing models. We also expect that the efficient and automated two-step classification method presented in this paper will be applicable to the ∼4 mag deeper gri stacks from the Rubin Observatory Legacy Survey of Space and Time (LSST) with minor adjustments.

scholarly journals Characterizing the abundance, properties, and kinematics of the cool circumgalactic medium of galaxies in absorption with SDSS DR16

2021 ◽  
Vol 504 (1) ◽  
pp. 65-88
Author(s):  
Abhijeet Anand ◽  
Dylan Nelson ◽  
Guinevere Kauffmann
Keyword(s):  
Formation Rate ◽  
Sloan Digital Sky Survey ◽  
Gas Absorption ◽  
Dark Matter Halo ◽  
Star Forming ◽  
Sky Survey ◽  
Optical Continuum ◽  
Circumgalactic Medium ◽  
Emission Line Galaxies ◽  
Red Galaxies

ABSTRACT In order to study the circumgalactic medium (CGM) of galaxies we develop an automated pipeline to estimate the optical continuum of quasars and detect intervening metal absorption line systems with a matched kernel convolution technique and adaptive S/N criteria. We process ∼ one million quasars in the latest Data Release 16 (DR16) of the Sloan Digital Sky Survey (SDSS) and compile a large sample of ∼ 160 000 Mg ii absorbers, together with ∼ 70 000 Fe ii systems, in the redshift range 0.35 < zabs < 2.3. Combining these with the SDSS DR16 spectroscopy of ∼1.1 million luminous red galaxies (LRGs) and ∼200 000 emission line galaxies (ELGs), we investigate the nature of cold gas absorption at 0.5 < z < 1. These large samples allow us to characterize the scale dependence of Mg ii with greater accuracy than in previous work. We find that there is a strong enhancement of Mg ii absorption within ∼50 kpc of ELGs, and the covering fraction within 0.5rvir of ELGs is 2–5 times higher than for LRGs. Beyond 50 kpc, there is a sharp decline in Mg ii for both kinds of galaxies, indicating a transition to the regime where the CGM is tightly linked with the dark matter halo. The Mg ii-covering fraction correlates strongly with stellar mass for LRGs, but weakly for ELGs, where covering fractions increase with star formation rate. Our analysis implies that cool circumgalactic gas has a different physical origin for star-forming versus quiescent galaxies.

scholarly journals Searching for Mg ii absorbers in and around galaxy clusters

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.

scholarly journals Red Misfits in the Sloan Digital Sky Survey: properties of star-forming red galaxies

2018 ◽  
Vol 476 (4) ◽  
pp. 5284-5302 ◽  
Author(s):  
Fraser A Evans ◽  
Laura C Parker ◽  
Ian D Roberts
Keyword(s):  
Sloan Digital Sky Survey ◽  
Star Forming ◽  
Sky Survey ◽  
Red Galaxies
Sign in / Sign up

Export Citation Format

Share Document