On the use of redshift surveys in observational cosmology

Observational cosmology

10.1093/oso/9780192895646.003.0025 ◽

2021 ◽

pp. 398-416

Author(s):

Andrew M. Steane

Keyword(s):

Deceleration Parameter ◽

Hubble Parameter ◽

Statistical Error ◽

Simple Calculation ◽

Observational Cosmology ◽

Spatial Curvature ◽

Sky Surveys ◽

Redshift Surveys ◽

Accelerating Expansion ◽

Age Estimates

The main strands of observation in cosmology are presented. These are redshift surveys using standard candles; galaxy distributions; age estimates drawing on a number of strands of evidence; and the CMB radiation. The chapter begins with a discussion of systemtic and statistical error in measurements, and explains the terminology of “Lambda CDM” model. Observations are combined with the Friedman equation in order to constrain the density parameters in a LCDM model. Data from supernova surveys are used to obtain the Hubble parameter and the deceleration parameter, and hence evidence of an accelerating expansion. Evidence of the BAO process is deduced from sky surveys, and used to constrain the spatial curvature. The CMB radiation is discussed at length. The Sachs-Wolfe effect is obtained by a simple calculation,. The method to deduce spatial curvature from the position of the acoustic peaks is outlined. Further features such as spectal index and polarization are briefly discussed.

Download Full-text

Redshift Surveys and Cosmology: A Summary of the Dunk Island Conference

Publications of the Astronomical Society of Australia ◽

10.1071/as00037 ◽

2000 ◽

Vol 17 (3) ◽

pp. 215-226 ◽

Cited By ~ 2

Author(s):

Matthew Colless

Keyword(s):

Large Scale ◽

Large Datasets ◽

Observational Cosmology ◽

Redshift Surveys ◽

Coral Sea ◽

Wide Range ◽

The Galaxy ◽

Very Large Datasets ◽

Galaxy Population ◽

New Generation

AbstractRedshift surveys constitute one of the prime tools of observational cosmology. Imaging surveys of the whole sky are now available at a wide range of wavelengths, and provide a basis for the new generation of massive redshift surveys currently in progress. The very large datasets produced by these surveys call for new and sophisticated approaches to the analysis of large-scale structure and the galaxy population. These issues, and some preliminary results from the new redshift surveys, were discussed at the second Coral Sea Cosmology Conference, held at Dunk Island on 24–28 August 1999. This is a summary of the conference; the full conference proceedings are on the WWW at http://www.mso.anu.edu.au/DunkIsland/Proceedings.

Download Full-text

Large High Redshift Spectroscopic Surveys

Proceedings of the International Astronomical Union ◽

10.1017/s1743921311022605 ◽

2010 ◽

Vol 6 (S277) ◽

pp. 121-127

Author(s):

Olivier Le Fèvre

Keyword(s):

Galaxy Evolution ◽

Mass Density ◽

High Redshift ◽

Sample Selection ◽

Global Perspective ◽

Observational Cosmology ◽

Wide Field ◽

Redshift Distribution ◽

Redshift Surveys ◽

Mass Assembly

AbstractDeep spectroscopic redshift surveys have become an important tool for observational cosmology, supported by a new generation of wide field multi-object spectrographs. They bring high redshift accuracy and a wealth of spectral features necessary for precision astrophysics and have led to the outstanding progress in our understanding of the different phases of galaxy evolution. The measurement of the evolution of volume quantities like the luminosity and mass functions or the correlation function, has enabled a deep insight into galaxy evolution since redshifts z ≃ 7. The redshift distribution N(z,m) is a basic property but is still difficult to be reproduced by models. We have now a global perspective on the history of star formation with a peak at z = 1−2 but the decline in SFRD at higher redshifts is still to be confirmed. The evolution of the stellar mass density with a fast growth in red passive galaxies between z = 2 and z = 1 is well established. The contribution to galaxy mass assembly of key physical processes like merging or cold accretion is now well documented. However, the pioneer measurements at the high redshift end z > > 1 remain to be consolidated with robust sample selection and statistical accuracy from large spectroscopic redshift surveys, a challenge for the years to come.

Download Full-text

Large-Scale Flows in the Local Universe

Symposium - International Astronomical Union ◽

10.1017/s0074180900110058 ◽

1996 ◽

Vol 168 ◽

pp. 175-182 ◽

Cited By ~ 1

Author(s):

D.S. Mathewson ◽

V.L. Ford

Keyword(s):

Large Scale ◽

Velocity Measurements ◽

Local Universe ◽

Peculiar Velocities ◽

Redshift Surveys ◽

Density Maps ◽

The Universe ◽

Great Wall ◽

Great Attractor ◽

Streaming Flow

Peculiar velocity measurements of 2500 southern spiral galaxies show large-scale flows in the direction of the Hydra-Centaurus clusters which fully participate in the flow themselves. The flow is not uniform over this region and seems to be associated with the denser regions which participate in the flow of amplitude about 400km/s. In the less dense regions the flow is small or non-existent. This makes the flow quite asymmetric and inconsistent with that expected from large-scale, parallel streaming flow that includes all galaxies out to 6000km/s as previously thought. The flow cannot be modelled by a Great Attractor at 4300km/s or the Centaurus clusters at 3500km/s. Indeed, from the density maps derived from the redshift surveys of “optical” and IRAS galaxies, it is difficult to see how the mass concentrations can be responsible particularly as they themselves participate in the flow. These results bring into question the generally accepted reason for the peculiar velocities of galaxies that they arise solely as a consequence of infall into the dense regions of the universe. To the N. of the Great Attractor region, the flow increases and shows no sign of diminishing out to the redshift limit of 8000km/s in this direction. We may have detected flow in the nearest section of the Great Wall.

Download Full-text

Redshift-space effects in voids and their impact on cosmological tests. Part I: the void size function

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3252 ◽

2020 ◽

Vol 500 (1) ◽

pp. 911-925

Author(s):

Carlos M Correa ◽

Dante J Paz ◽

Ariel G Sánchez ◽

Andrés N Ruiz ◽

Nelson D Padilla ◽

...

Keyword(s):

Theoretical Framework ◽

Real Space ◽

Global Dynamics ◽

Void Size ◽

Spherical Void ◽

Cosmological Constraints ◽

Redshift Surveys ◽

Size Function ◽

Expansion Effect ◽

Space Effects

ABSTRACT Voids are promising cosmological probes. Nevertheless, every cosmological test based on voids must necessarily employ methods to identify them in redshift space. Therefore, redshift-space distortions (RSD) and the Alcock–Paczyński effect (AP) have an impact on the void identification process itself generating distortion patterns in observations. Using a spherical void finder, we developed a statistical and theoretical framework to describe physically the connection between the identification in real and redshift space. We found that redshift-space voids above the shot noise level have a unique real-space counterpart spanning the same region of space, they are systematically bigger and their centres are preferentially shifted along the line of sight. The expansion effect is a by-product of RSD induced by tracer dynamics at scales around the void radius, whereas the off-centring effect constitutes a different class of RSD induced at larger scales by the global dynamics of the whole region containing the void. The volume of voids is also altered by the fiducial cosmology assumed to measure distances, this is the AP change of volume. These three systematics have an impact on cosmological statistics. In this work, we focus on the void size function. We developed a theoretical framework to model these effects and tested it with a numerical simulation, recovering the statistical properties of the abundance of voids in real space. This description depends strongly on cosmology. Hence, we lay the foundations for improvements in current models of the abundance of voids in order to obtain unbiased cosmological constraints from redshift surveys.

Download Full-text

Deconstructing the neutrino mass constraint from galaxy redshift surveys

Journal of Cosmology and Astroparticle Physics ◽

10.1088/1475-7516/2018/03/035 ◽

2018 ◽

Vol 2018 (03) ◽

pp. 035-035 ◽

Cited By ~ 27

Author(s):

Aoife Boyle ◽

Eiichiro Komatsu

Keyword(s):

Neutrino Mass ◽

Redshift Surveys ◽

Mass Constraint ◽

Galaxy Redshift

Download Full-text

Astronomy on Ice

Publications of the Astronomical Society of Australia ◽

10.1017/s1323358000018282 ◽

1986 ◽

Vol 6 (4) ◽

pp. 403-415 ◽

Cited By ~ 5

Author(s):

Martin A. Pomerantz

Keyword(s):

Gamma Ray ◽

Far Infrared ◽

The United States ◽

High Energy ◽

Observational Cosmology ◽

Significant Information ◽

Infrared Measurements ◽

Energy Gamma ◽

Low Humidity ◽

Scientific Station

AbstractThe geographic South Pole, where the United States maintains a year-round scientific station, affords a number of unique advantages for certain types of astronomical observations. These include: continuous viewing and constant declination of ail objects in the southern celestial hemisphere, exceedingly low humidity, extended periods of coronal seeing, high altitude, and uniform terrain. The areas of research that have already benefited immensely from thèse extraordinary features are helioseismology and submillimeter astronomy. Unparalleled observations of global solar oscillations have already yielded significant information about the structure and dynamics of the Sun’s interior. Far infrared measurements of various galactic and extra-galactic regions have attained an unprecedented level of sensitivity, limited for the first time only by the noise inherent in the detector. In addition to further helioseismological observations, currently planned future activities include observational cosmology and ultra high energy gamma ray astronomy.

Download Full-text