skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: A direct measurement of the high-mass end of the velocity dispersion function at z ~ 0.55 from SDSS-III/BOSS

Abstract

When two galaxies that are distant from one another (and also distant from Earth) happen to lie along a single line of sight in the sky, the resulting phenomenon is known as a “gravitational lens.” The gravity of the more nearby galaxy warps the image of the more distant galaxy into multiple images or complete rings (know as “Einstein rings” since the quantitative description of the gravitational lensing effect relies on Einstein’s theory of gravity.) Strong gravitational lens systems have multiple scientific applications. If the more distant galaxy happens to contain a time-varying quasar (bright emission powered by a supermassive black hole at the galaxy’s center) or supernova explosion, the time delay between multiple images can be used as a probe of the expansion rate of the universe (and other cosmological parameters.) Forecasting the incidence of gravitational lenses in future large-scale sky surveys relies on quantifying the population of potential lens galaxies in the universe in terms of their abundance and their lensing efficiency. The lensing efficiency is most directly correlated with the galaxy’s “velocity dispersion:” the characteristic speed with which stars in the galaxy are orbiting under the influence of the galaxy’s overall gravitational field. This paper uses previousmore » results quantifying the combined demographics of galaxies in brightness and velocity dispersion to compute the demographics of massive “elliptical” galaxies in velocity dispersion alone, thereby providing the essential ingredient for forecasting the expected incidence of strong gravitational lensing by these types of galaxies in future sky surveys such as DESI and LSST. These results are also applicable to the association of massive galaxies with their associated dark-matter “halos,” which is an essential ingredient for the most accurate and informative extraction of cosmological parameters from the data sets produced by large-scale surveys of the universe.« less

Authors:
 [1];  [2];  [3]
  1. The Univ. of Utah, Salt Lake City, UT (United States)
  2. The Univ. of Utah, Salt Lake City, UT (United States); National Optical Astronomy Observatory (NOAO), Tucson, AZ (United States)
  3. Chinese Academy of Sciences (CAS), Beijing (China)
Publication Date:
Research Org.:
Univ. of Utah, Salt Lake City, UT (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
OSTI Identifier:
1419944
Grant/Contract Number:
SC0010331
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Monthly Notices of the Royal Astronomical Society
Additional Journal Information:
Journal Volume: 468; Journal Issue: 1; Journal ID: ISSN 0035-8711
Publisher:
Royal Astronomical Society
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 79 ASTRONOMY AND ASTROPHYSICS; surveys; galaxies: evolution; galaxies: statistics; methods: analytical; methods: statistical

Citation Formats

Montero-Dorta, Antonio D., Bolton, Adam S., and Shu, Yiping. A direct measurement of the high-mass end of the velocity dispersion function at z ~ 0.55 from SDSS-III/BOSS. United States: N. p., 2017. Web. doi:10.1093/mnras/stx321.
Montero-Dorta, Antonio D., Bolton, Adam S., & Shu, Yiping. A direct measurement of the high-mass end of the velocity dispersion function at z ~ 0.55 from SDSS-III/BOSS. United States. doi:10.1093/mnras/stx321.
Montero-Dorta, Antonio D., Bolton, Adam S., and Shu, Yiping. Fri . "A direct measurement of the high-mass end of the velocity dispersion function at z ~ 0.55 from SDSS-III/BOSS". United States. doi:10.1093/mnras/stx321. https://www.osti.gov/servlets/purl/1419944.
@article{osti_1419944,
title = {A direct measurement of the high-mass end of the velocity dispersion function at z ~ 0.55 from SDSS-III/BOSS},
author = {Montero-Dorta, Antonio D. and Bolton, Adam S. and Shu, Yiping},
abstractNote = {When two galaxies that are distant from one another (and also distant from Earth) happen to lie along a single line of sight in the sky, the resulting phenomenon is known as a “gravitational lens.” The gravity of the more nearby galaxy warps the image of the more distant galaxy into multiple images or complete rings (know as “Einstein rings” since the quantitative description of the gravitational lensing effect relies on Einstein’s theory of gravity.) Strong gravitational lens systems have multiple scientific applications. If the more distant galaxy happens to contain a time-varying quasar (bright emission powered by a supermassive black hole at the galaxy’s center) or supernova explosion, the time delay between multiple images can be used as a probe of the expansion rate of the universe (and other cosmological parameters.) Forecasting the incidence of gravitational lenses in future large-scale sky surveys relies on quantifying the population of potential lens galaxies in the universe in terms of their abundance and their lensing efficiency. The lensing efficiency is most directly correlated with the galaxy’s “velocity dispersion:” the characteristic speed with which stars in the galaxy are orbiting under the influence of the galaxy’s overall gravitational field. This paper uses previous results quantifying the combined demographics of galaxies in brightness and velocity dispersion to compute the demographics of massive “elliptical” galaxies in velocity dispersion alone, thereby providing the essential ingredient for forecasting the expected incidence of strong gravitational lensing by these types of galaxies in future sky surveys such as DESI and LSST. These results are also applicable to the association of massive galaxies with their associated dark-matter “halos,” which is an essential ingredient for the most accurate and informative extraction of cosmological parameters from the data sets produced by large-scale surveys of the universe.},
doi = {10.1093/mnras/stx321},
journal = {Monthly Notices of the Royal Astronomical Society},
number = 1,
volume = 468,
place = {United States},
year = {Fri Feb 24 00:00:00 EST 2017},
month = {Fri Feb 24 00:00:00 EST 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 1work
Citation information provided by
Web of Science

Save / Share:
  • The history of the expanding universe is encoded in the large-scale distribution of galaxies throughout space. By mapping out the three-dimensional locations of millions of galaxies with powerful telescopes, we can directly measure this expansion history. When interpreted using Einstein's theory of gravity, this expansion history lets us infer the contents of the universe, including the amount and nature of "dark energy", an as-yet unexplained energy density associated with the empty vacuum of space. However, to make these measurements and inferences accurately, we must understand and control for a large number of experimental effects. This paper develops a novel methodmore » for large cosmological galaxy surveys, and applies it to data from the "BOSS" experiment of the Third Sloan Digital Sky Survey. This method enables an accurate statistical characterization of the "completeness" of the BOSS experiment: the probability that a given galaxy at a given place in the universe is actually detected and successfully measured. It also enables the accurate determination of the underlying demographics of the galaxy population being studied by the experiment. These two ingredients can then be used to make a more accurate comparison between the results of the experiment and the theoretical models that predict the observable effects of dark energy.« less
  • We present a statistical study of the luminosity functions of galaxies surrounding luminous red galaxies (LRGs) at average redshifts (z) = 0.34 and (z) = 0.65. The luminosity functions are derived by extracting source photometry around more than 40,000 LRGs and subtracting foreground and background contamination using randomly selected control fields. We show that at both studied redshifts the average luminosity functions of the LRGs and their satellite galaxies are poorly fitted by a Schechter function due to a luminosity gap between the centrals and their most luminous satellites. We utilize a two-component fit of a Schechter function plus amore » log-normal distribution to demonstrate that LRGs are typically brighter than their most luminous satellite by roughly 1.3 mag. This luminosity gap implies that interactions within LRG environments are typically restricted to minor mergers with mass ratios of 1:4 or lower. The luminosity functions further imply that roughly 35% of the mass in the environment is locked in the LRG itself, supporting the idea that mass growth through major mergers within the environment is unlikely. Lastly, we show that the luminosity gap may be at least partially explained by the selection of LRGs as the gap can be reproduced by sparsely sampling a Schechter function. In that case LRGs may represent only a small fraction of central galaxies in similar mass halos.« less
  • The Lyα forest transmission probability distribution function (PDF) is an established probe of the intergalactic medium (IGM) astrophysics, especially the temperature-density relationship of the IGM. We measure the transmission PDF from 3393 Baryon Oscillations Spectroscopic Survey (BOSS) quasars from Sloan Digital Sky Survey Data Release 9, and compare with mock spectra that include careful modeling of the noise, continuum, and astrophysical uncertainties. The BOSS transmission PDFs, measured at (z) = [2.3, 2.6, 3.0], are compared with PDFs created from mock spectra drawn from a suite of hydrodynamical simulations that sample the IGM temperature-density relationship, γ, and temperature at mean density,more » T {sub 0}, where T(Δ) = T {sub 0}Δ{sup γ} {sup –} {sup 1}. We find that a significant population of partial Lyman-limit systems (LLSs) with a column-density distribution slope of β{sub pLLS} ∼ – 2 are required to explain the data at the low-transmission end of transmission PDF, while uncertainties in the mean Lyα forest transmission affect the high-transmission end. After modeling the LLSs and marginalizing over mean transmission uncertainties, we find that γ = 1.6 best describes the data over our entire redshift range, although constraints on T {sub 0} are affected by systematic uncertainties. Within our model framework, isothermal or inverted temperature-density relationships (γ ≤ 1) are disfavored at a significance of over 4σ, although this could be somewhat weakened by cosmological and astrophysical uncertainties that we did not model.« less
  • Here, we present an anisotropic analysis of the baryon acoustic oscillation (BAO) scale in the twelfth and final data release of the Baryon Oscillation Spectroscopic Survey (BOSS). We independently analyse the LOWZ and CMASS galaxy samples: the LOWZ sample contains 361 762 galaxies with an effective redshift of zLOWZ = 0.32; the CMASS sample consists of 777 202 galaxies with an effective redshift of zCMASS = 0.57. We extract the BAO peak position from the monopole power-spectrum moment, α0, and from the μ 2 moment, α2, where μ is the cosine of the angle to the line of sight. Themore » μ 2-moment provides equivalent information to that available in the quadrupole but is simpler to analyse. After applying a reconstruction algorithm to reduce the BAO suppression by bulk motions, we measure the BAO peak position in the monopole and μ 2-moment, which are related to radial and angular shifts in scale. We report H(zLOWZ)r s(zd) = (11.60 ± 0.60) × 10 3 km s -1 and D A(zLOWZ)/r s(zd) = 6.66 ± 0.16 with a cross-correlation coefficient of rHD A = 0.41, for the LOWZ sample; and H(zCMASS)r s(zd) = (14.56 ± 0.37) × 10 3 km s -1 and D A(zCMASS)/r s(z d) = 9.42 ± 0.13 with a cross-correlation coefficient of rHD A = 0.47, for the CMASS sample.« less
  • We measure the intrinsic relation between velocity dispersion (σ) and luminosity (L) for massive, luminous red galaxies at redshift z ~ 0.55. Here, we achieve unprecedented precision by using a sample of 600 000 galaxies with spectra from the Baryon Oscillation Spectroscopic Survey of the third Sloan Digital Sky Survey (SDSS-III), covering a range of stellar masses M* ≳ 10 11M . We deconvolve the effects of photometric errors, limited spectroscopic signal-to-noise ratio, and red–blue galaxy confusion using a novel hierarchical Bayesian formalism that is generally applicable to any combination of photometric and spectroscopic observables. For an L–σ relation ofmore » the form L ∝ σ β, we find β = 7.8 ± 1.1 for σ corrected to the effective radius, and a very small intrinsic scatter of s = 0.047 ± 0.004 in log10σ at fixed L. No significant redshift evolution is found for these parameters. The evolution of the zero-point within the redshift range considered is consistent with the passive evolution of a galaxy population that formed at redshift z = 2–3, assuming single stellar populations. An analysis of previously reported results seems to indicate that the passively evolved high-mass L–σ relation at z ~ 0.55 is consistent with the one measured at z = 0.1. Finally, our results, in combination with those presented in the LF work of Montero-Dorta et al., provide a detailed description of the high-mass end of the red sequence (RS) at z ~ 0.55. This characterization, in the light of previous literature, suggest that the high-mass RS distribution corresponds to the ‘core’ elliptical population.« less