scholarly journals Galaxy clusters as intrinsic alignment tracers: present and future

2020 ◽  
Vol 500 (4) ◽  
pp. 5561-5569
Author(s):  
C J G Vedder ◽  
N E Chisari
Keyword(s):  
Large Scale ◽  
Signal To Noise Ratio ◽  
Sloan Digital Sky Survey ◽  
Line Of Sight ◽  
Expected Number ◽  
Number Count ◽  
Sky Survey ◽  
Redshift Survey ◽  
Number Counts ◽  
The Universe

ABSTRACT Galaxies and clusters embedded in the large-scale structure of the Universe are observed to align in preferential directions. Galaxy alignment has been established as a potential probe for cosmological information, but the application of cluster alignments for these purposes remains unexplored. Clusters are observed to have a higher alignment amplitude than galaxies, but because galaxies are much more numerous, the trade-off in detectability between the two signals remains unclear. We present forecasts comparing cluster and galaxy alignments for two extragalactic survey set-ups: a currently available low-redshift survey (Sloan Digital Sky Survey, SDSS) and an upcoming higher redshift survey (Legacy Survey of Space and Time, LSST). For SDSS, we rely on the publicly available redmapper catalogue to describe the cluster sample. For LSST, we perform estimations of the expected number counts while we extrapolate the alignment measurements from SDSS. Clusters in SDSS have typically higher alignment signal-to-noise ratio (S/N) than galaxies. For LSST, the cluster alignment signals quickly wash out with redshift due to a relatively low number count and a decreasing alignment amplitude. Nevertheless, a potential strong suit of clusters is in their interplay with weak lensing: intrinsic alignments can be more easily isolated for clusters than for galaxies. The S/N of cluster alignment can in general be improved by isolating close pairs along the line of sight.

scholarly journals Searching for cross-correlation between stochastic gravitational-wave background and galaxy number counts

2020 ◽  
Vol 500 (2) ◽  
pp. 1666-1672
Author(s):  
Kate Z Yang ◽  
Vuk Mandic ◽  
Claudia Scarlata ◽  
Sharan Banagiri
Keyword(s):  
Gravitational Wave ◽  
Cross Correlation ◽  
Sloan Digital Sky Survey ◽  
Number Count ◽  
Frequency Bands ◽  
Galaxy Count ◽  
Harmonic Decomposition ◽  
Number Counts ◽  
Gravitational Wave Background ◽  
The Universe

ABSTRACT Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) and Advanced Virgo have recently published the upper limit measurement of persistent directional stochastic gravitational-wave background (SGWB) based on data from their first and second observing runs. In this paper, we investigate whether a correlation exists between this maximal likelihood SGWB map and the electromagnetic (EM) tracers of matter structure in the Universe, such as galaxy number counts. The method we develop will improve the sensitivity of future searches for anisotropy in the SGWB and expand the use of SGWB anisotropy to probe the formation of structure in the Universe. In order to compute the cross-correlation, we used the spherical harmonic decomposition of SGWB in multiple frequency bands and converted them into pixel-based sky maps in healpix basis. For the EM part, we use the Sloan Digital Sky Survey alaxy catalogue and form healpix sky maps of galaxy number counts at the same angular resolution as the SGWB maps. We compute the pixel-based coherence between these SGWB and galaxy count maps. After evaluating our results in different SGWB frequency bands and in different galaxy redshift bins, we conclude that the coherence between the SGWB and galaxy number count maps is dominated by the null measurement noise in the SGWB maps, and therefore not statistically significant. We expect the results of this analysis to be significantly improved by using the more sensitive upcoming SGWB measurements based on the third observing run of Advanced LIGO and Advanced Virgo.

scholarly journals Large Scale Structure of the Universe

1998 ◽  
Vol 179 ◽  
pp. 317-328 ◽  
Author(s):  
N.A. Bahcall
Keyword(s):  
Large Scale ◽  
Initial Conditions ◽  
Large Scale Structure ◽  
Density Fluctuations ◽  
Scale Structure ◽  
Sloan Digital Sky Survey ◽  
Sky Survey ◽  
Initial Spectrum ◽  
Formation And Evolution ◽  
The Universe

How is the universe organized on large scales? How did this structure evolve from the unknown initial conditions of a rather smooth early universe to the present time? The answers to these questions will shed light on the cosmology we live in, the amount, composition and distribution of matter in the universe, the initial spectrum of density fluctuations that gave rise to this structure, and the formation and evolution of galaxies, lusters of galaxies, and larger scale structures.To address these fundamental questions, large and accurate sky surveys are needed—in various wavelengths and to various depths. In this presentation I review current observational studies of large scale structure, present the constraints these observations place on cosmological models and on the amount of dark matter in the universe, and highlight some of the main unsolved problems in the field of large-scale structure that could be solved over the next decade with the aid of current and future surveys. I briefly discuss some of these surveys, including the Sloan Digital Sky Survey that will provide a complete imaging and spectroscopic survey of the high-latitude northern sky, with redshifts for the brightest ∼ 106 galaxies, 105 quasars, and 103.5 rich clusters of galaxies. The potentialities of the SDSS survey, as well as of cross-wavelength surveys, for resolving some of the unsolved problems in large-scale structure and cosmology are discussed.

scholarly journals Characterising filaments in the SDSS volume from the galaxy distribution

2020 ◽  
Vol 642 ◽  
pp. A19 ◽  
Author(s):  
Nicola Malavasi ◽  
Nabila Aghanim ◽  
Marian Douspis ◽  
Hideki Tanimura ◽  
Victor Bonjean
Keyword(s):  
Large Scale ◽  
Sloan Digital Sky Survey ◽  
Specific Method ◽  
Redshift Surveys ◽  
Galaxy Distribution ◽  
Systematic Uncertainties ◽  
Sky Survey ◽  
The Galaxy ◽  
Free Parameters ◽  
The Universe

Detecting the large-scale structure of the Universe based on the galaxy distribution and characterising its components is of fundamental importance in astrophysics but is also a difficult task to achieve. Wide-area spectroscopic redshift surveys are required to accurately measure galaxy positions in space that also need to cover large areas of the sky. It is also difficult to create algorithms that can extract cosmic web structures (e.g. filaments). Moreover, these detections will be affected by systematic uncertainties that stem from the characteristics of the survey used (e.g. its completeness and coverage) and from the unique properties of the specific method adopted to detect the cosmic web (i.e. the assumptions it relies on and the free parameters it may employ). For these reasons, the creation of new catalogues of cosmic web features on wide sky areas is important, as this allows users to have at their disposal a well-understood sample of structures whose systematic uncertainties have been thoroughly investigated. In this paper we present the filament catalogues created using the discrete persistent structure extractor tool in the Sloan Digital Sky Survey (SDSS), and we fully characterise them in terms of their dependence on the choice of parameters pertaining to the algorithm, and with respect to several systematic issues that may arise in the skeleton as a result of the properties of the galaxy distribution (such as Finger-of-God redshift distortions and defects of the density field that are due to the boundaries of the survey).

scholarly journals Combining friend-of-friend and halo-based algorithms for the identification of galaxy groups

2020 ◽  
Vol 636 ◽  
pp. A61
Author(s):  
Facundo Rodriguez ◽  
Manuel Merchán
Keyword(s):  
Analytical Model ◽  
Large Scale ◽  
Mass Range ◽  
Sloan Digital Sky Survey ◽  
Bright Galaxy ◽  
Galaxy Groups ◽  
Sky Survey ◽  
The Universe ◽  
Bounded System

Context. Galaxy groups provide the means for a great diversity of studies that contribute to a better understanding of the structure of the universe on a large scale and allow the properties of galaxies to be linked to those of the host halos. However, the identification of galaxy systems is a challenging task and therefore it is necessary to improve the techniques involved as much as possible. Aims. In view of the large present and forthcoming galaxy catalogues, we propose, implement, and evaluate an algorithm that combines the two most popular techniques used to identify galaxy systems. The algorithm can be easily applied to any spectroscopic galaxy catalogue, but here we demonstrate its use on the Sloan Digital Sky Survey. Methods. Assuming that a galaxy group is a gravitationally bounded system that has at least one bright galaxy, we begin by identifying groups with a friends-of-friends algorithm adapted to fit this definition. In view of the shortcomings of this method, particularly the lack of ability to identify low-number groups, and consequently the inability to study the occupation of halos throughout the mass range, we improve it by adding a halo-based procedure. To assess the performance, we construct a mock catalogue from a semi-analytical model to compare the groups identified using our method with those obtained from the simulation. Results. The comparison of groups extracted using our method with those of a mock catalogue shows that the proposed algorithm provides excellent results. The modifications introduced to the friends-of-friends algorithm in the first part of the procedure to fit the adopted group definition gave reliable groups. Furthermore, incorporation of the halo-based method reduces the interlopers while more accurately reproducing the number of galaxies per group. As a specific application, we use the algorithm to extract groups from the Sloan Digital Sky Survey.

scholarly journals Identification of Extremely Large Scale Structures in SDSS-III

2014 ◽  
Vol 11 (S308) ◽  
pp. 299-300
Author(s):  
Shishir Sankhyayan ◽  
J. Bagchi ◽  
P. Sarkar ◽  
V. Sahni ◽  
J. Jacob
Keyword(s):  
Large Scale ◽  
Sloan Digital Sky Survey ◽  
Limited Sample ◽  
Large Scale Structures ◽  
Large Structures ◽  
Density Peaks ◽  
Redshift Surveys ◽  
Sky Survey ◽  
Scale Structures ◽  
The Universe

AbstractWe have initiated the search and detailed study of large scale structures present in the universe using galaxy redshift surveys. In this process, we take the volume-limited sample of galaxies from Sloan Digital Sky Survey III and find very large structures even beyond the redshift of 0.2. One of the structures is even greater than 600 Mpc which raises a question on the homogeneity scale of the universe. The shapes of voids-structures (adjacent to each other) seem to be correlated, which supports the physical existence of the observed structures. The other observational supports include galaxy clusters' and QSO distribution's correlation with the density peaks of the volume limited sample of galaxies.

scholarly journals Detecting multi-scale filaments in galaxy distribution

2014 ◽  
Vol 10 (S306) ◽  
pp. 45-47
Author(s):  
Elmo Tempel
Keyword(s):  
Point Process ◽  
Large Scale ◽  
Three Dimensional ◽  
Sloan Digital Sky Survey ◽  
Point Distribution ◽  
Multi Scale ◽  
Galaxy Distribution ◽  
Sky Survey ◽  
The Galaxy ◽  
Redshift Survey

AbstractThe main feature of the spatial large-scale galaxy distribution is its intricate network of galaxy filaments. This network is spanned by the galaxy locations that can be interpreted as a three-dimensional point distribution. The global properties of the point process can be measured by different statistical methods, which, however, do not describe directly the structure elements. The morphology of the large-scale structure, on the other hand, is an important property of the galaxy distribution. Here, we apply an object point process with interactions (the Bisous model) to trace and extract the filamentary network in the presently largest galaxy redshift survey, the Sloan Digital Sky Survey (SDSS data release 10). We search for multi-scale filaments in the galaxy distribution that have a radius of about 0.5, 1.0, 2.0, and 4.0h−1Mpc. We extract the spines of the filamentary network and divide the detected network into single filaments.

Spatial Variations of Galaxy Number Counts in the Sloan Digital Sky Survey. I. Extinction, Large-Scale Structure, and Photometric Homogeneity

2004 ◽  
Vol 127 (6) ◽  
pp. 3155-3160 ◽  
Author(s):  
Masataka Fukugita ◽  
Naoki Yasuda ◽  
Jon Brinkmann ◽  
James E. Gunn ◽  
Željko Ivezić ◽  
...  
Keyword(s):  
Large Scale ◽  
Large Scale Structure ◽  
Spatial Variations ◽  
Scale Structure ◽  
Sloan Digital Sky Survey ◽  
Sky Survey ◽  
Number Counts

scholarly journals X-Ray and Radio Emissions of AWM and MKW Clusters

2012 ◽  
Author(s):  
Michael Ramuta
Keyword(s):  
Large Scale ◽  
Life Cycles ◽  
Sloan Digital Sky Survey ◽  
X Ray ◽  
Large Scale Structures ◽  
Sky Survey ◽  
Scale Structures ◽  
Using Data ◽  
And Behavior ◽  
The Universe

A grasp of the life-cycles of large-scale structures is critical to understanding the Universe. This can be accomplished through the study of poor clusters-- that is, younger clusters that are likely evolving to another state. The selected clusters are significant in that they are poor but also possess a type-cD galaxy. This brighter central galaxy suggests that these clusters may be dynamically evolved and are potential candidates for fossil groups. In order to more fully understand the structure and behavior of poor galaxy clusters, 12 clusters were selected and analyzed. Using data from the Sloan Digital Sky Survey, Chandra X-Ray Archive, and the VLA FIRST Survey, we present x-ray profiles and radio observations of these 12 galaxy clusters. 

scholarly journals Like a spider in its web: a study of the large-scale structure around the Coma cluster

2020 ◽  
Vol 634 ◽  
pp. A30 ◽  
Author(s):  
Nicola Malavasi ◽  
Nabila Aghanim ◽  
Hideki Tanimura ◽  
Victor Bonjean ◽  
Marian Douspis
Keyword(s):  
Large Scale ◽  
Sloan Digital Sky Survey ◽  
Direct Result ◽  
Central Position ◽  
Clusters Of Galaxies ◽  
Coma Cluster ◽  
Sky Survey ◽  
Galaxy Sample ◽  
Occupy Central ◽  
The Universe

The Cosmic Web is a complex network of filaments, walls, and voids that represent the largest structures in the Universe. In this network, which is the direct result of structure formation, galaxy clusters occupy central positions that form the nodes and these are connected by filaments. In this work, we investigate the position in the Cosmic Web of one of the most well-known and best-studied clusters of galaxies, the Coma cluster. We make use of the Sloan Digital Sky Survey Data Release 7 Main Galaxy Sample and of the Discrete Persistent Structure Extractor to detect large-scale filaments around the Coma cluster and analyse the properties of the Cosmic Web. We study the network of filaments around Coma in a region of 75 Mpc in radius. We find that the Coma cluster has a median connectivity of 2.5, in agreement with measurements from clusters of similar mass in the literature as well as with what is expected from numerical simulations. Coma is indeed connected to three secure filaments which connect it to Abell 1367 and to several other clusters in the field. The location of these filaments in the vicinity of Coma is consistent with features detected in the X-ray, as well as the likely direction of infall of galaxies, such as for example NGC 4839. The overall picture that emerges of the Coma cluster is that of a highly connected structure occupying a central position as a dense node of the Cosmic Web. We also find a tentative detection, at 2.1σ significance, of the filaments in the SZ signal.

scholarly journals Clustering and Halo Occupation Distribution of Active Galactic Nuclei

2013 ◽  
Vol 9 (S304) ◽  
pp. 243-243
Author(s):  
Takamitsu Miyaji ◽  
M. Krumpe ◽  
A. Coil ◽  
H. Aceves ◽  
B. Husemann
Keyword(s):  
Cross Correlation ◽  
Dynamic Range ◽  
Signal To Noise Ratio ◽  
Sloan Digital Sky Survey ◽  
Dark Matter Halo ◽  
Bias Parameter ◽  
X Ray ◽  
Sky Survey ◽  
Galaxy Population ◽  
Halo Occupation Distribution

AbstractWe present the results of our series of studies on correlation function and halo occupation distribution of AGNs utilizing data the ROSAT All-Sky Survey (RASS) and the Sloan Digital Sky Survey (SDSS) in the redshift range of 0.07<z<0.36. In order to improve the signal-to-noise ratio, we take cross-correlation approach, where cross-correlation functions (CCF) between AGNs and much more numerous AGNs are analyzed. The calculated CCFs are analyzed using the Halo Occupation Distribution (HOD) model, where the CCFs are divided into the term contributed by the AGN-galaxy pairs that reside in one dark matter halo (DMH), (the 1-halo term) and those from two different DMHs (the 2-halo term). The 2-halo term is the indicator of the bias parameter, which is a function of the typical mass of the DMHs in which AGNs reside. The combination of the 1-halo and 2-halo terms gives, not only the typical DMH mass, but also how the AGNs are distributed among the DMHs as a function of mass separately for those at the center of the DMHs and satellites. The main results are as follows: (1) the range of typical mass of the DMHs in various sub-samples of AGNs log (MDMH/h−1MΘ) ~ 12.4–13.4, (2) we found a dependence of the AGN bias parameter on the X-ray luminosity of AGNs, while the optical luminosity dependence is not significant probably due to smaller dynamic range in luminosity for the optically-selected sample, and (3) the growth of the number of AGNs per DMH (N (MDMH)) with MDMH is shallow, or even may be flat, contrary to that of the galaxy population in general, which grows with MDMH proportionally, suggesting a suppression of AGN triggering in denser environment. In order to investigate the origin of the X-ray luminosity dependence, we are also investigating the dependence of clustering on the black hole mass and the Eddington ratio, we also present the results of this investigation.

Sign in / Sign up

Export Citation Format

Share Document