The cross-correlation of Mg II absorption and galaxies in BOSS

Ignasi Pérez-Ràfols, Jordi Miralda-Escudé, Britt Lundgren, Jian Ge, Patrick Petitjean, Donald P. Schneider, Donald G. York, Benjamin A. Weaver

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

We present a measurement of the cross-correlation of MgII absorption and massive galaxies, using the Data Release (DR)11 main galaxy sample of the Baryon Oscillation Spectroscopic Survey (BOSS) of Sloan Digital Sky Survey III (SDSS-III; CMASS galaxies), and the DR7 quasar spectra of SDSS-II. The cross-correlation is measured by stacking quasar absorption spectra shifted to the redshift of galaxies that are within a certain impact parameter bin of the quasar, after dividing by a quasar continuum model. This results in an average MgII equivalent width as a function of impact parameter from a galaxy, ranging from 50 kpc to more than 10 Mpc in proper units, which includes all Mg II absorbers. We show that special care needs to be taken to use an unbiased quasar continuum estimator, to avoid systematic errors in the measurement of the mean stacked MgII equivalent width. The measured cross-correlation follows the expected shape of the galaxy correlation function, although measurement errors are large. We use the cross-correlation amplitude to derive the bias factor of MgII absorbers, finding bMg II = 2.33 ± 0.19, where the error accounts only for the statistical uncertainty in measuring the mean equivalent width. This bias factor is larger than that obtained in previous studies and may be affected by modelling uncertainties that we discuss, but if correct it suggests that MgII absorbers at redshift z ≃ 0.5 are spatially distributed on large scales similarly to the CMASS galaxies in BOSS.

Original languageEnglish (US)
Pages (from-to)2784-2802
Number of pages19
JournalMonthly Notices of the Royal Astronomical Society
Volume447
Issue number3
DOIs
StatePublished - Jan 1 2015

Fingerprint

cross correlation
baryons
oscillation
galaxies
quasars
oscillations
absorbers
absorption spectrum
continuums
stacking
estimators
systematic errors
absorption spectra
modeling
parameter

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Pérez-Ràfols, I., Miralda-Escudé, J., Lundgren, B., Ge, J., Petitjean, P., Schneider, D. P., ... Weaver, B. A. (2015). The cross-correlation of Mg II absorption and galaxies in BOSS. Monthly Notices of the Royal Astronomical Society, 447(3), 2784-2802. https://doi.org/10.1093/mnras/stu2645
Pérez-Ràfols, Ignasi ; Miralda-Escudé, Jordi ; Lundgren, Britt ; Ge, Jian ; Petitjean, Patrick ; Schneider, Donald P. ; York, Donald G. ; Weaver, Benjamin A. / The cross-correlation of Mg II absorption and galaxies in BOSS. In: Monthly Notices of the Royal Astronomical Society. 2015 ; Vol. 447, No. 3. pp. 2784-2802.
@article{94fb7eb75e9c483a89aa84fad0431fd1,
title = "The cross-correlation of Mg II absorption and galaxies in BOSS",
abstract = "We present a measurement of the cross-correlation of MgII absorption and massive galaxies, using the Data Release (DR)11 main galaxy sample of the Baryon Oscillation Spectroscopic Survey (BOSS) of Sloan Digital Sky Survey III (SDSS-III; CMASS galaxies), and the DR7 quasar spectra of SDSS-II. The cross-correlation is measured by stacking quasar absorption spectra shifted to the redshift of galaxies that are within a certain impact parameter bin of the quasar, after dividing by a quasar continuum model. This results in an average MgII equivalent width as a function of impact parameter from a galaxy, ranging from 50 kpc to more than 10 Mpc in proper units, which includes all Mg II absorbers. We show that special care needs to be taken to use an unbiased quasar continuum estimator, to avoid systematic errors in the measurement of the mean stacked MgII equivalent width. The measured cross-correlation follows the expected shape of the galaxy correlation function, although measurement errors are large. We use the cross-correlation amplitude to derive the bias factor of MgII absorbers, finding bMg II = 2.33 ± 0.19, where the error accounts only for the statistical uncertainty in measuring the mean equivalent width. This bias factor is larger than that obtained in previous studies and may be affected by modelling uncertainties that we discuss, but if correct it suggests that MgII absorbers at redshift z ≃ 0.5 are spatially distributed on large scales similarly to the CMASS galaxies in BOSS.",
author = "Ignasi P{\'e}rez-R{\`a}fols and Jordi Miralda-Escud{\'e} and Britt Lundgren and Jian Ge and Patrick Petitjean and Schneider, {Donald P.} and York, {Donald G.} and Weaver, {Benjamin A.}",
year = "2015",
month = "1",
day = "1",
doi = "10.1093/mnras/stu2645",
language = "English (US)",
volume = "447",
pages = "2784--2802",
journal = "Monthly Notices of the Royal Astronomical Society",
issn = "0035-8711",
publisher = "Oxford University Press",
number = "3",

}

Pérez-Ràfols, I, Miralda-Escudé, J, Lundgren, B, Ge, J, Petitjean, P, Schneider, DP, York, DG & Weaver, BA 2015, 'The cross-correlation of Mg II absorption and galaxies in BOSS', Monthly Notices of the Royal Astronomical Society, vol. 447, no. 3, pp. 2784-2802. https://doi.org/10.1093/mnras/stu2645

The cross-correlation of Mg II absorption and galaxies in BOSS. / Pérez-Ràfols, Ignasi; Miralda-Escudé, Jordi; Lundgren, Britt; Ge, Jian; Petitjean, Patrick; Schneider, Donald P.; York, Donald G.; Weaver, Benjamin A.

In: Monthly Notices of the Royal Astronomical Society, Vol. 447, No. 3, 01.01.2015, p. 2784-2802.

Research output: Contribution to journalArticle

TY - JOUR

T1 - The cross-correlation of Mg II absorption and galaxies in BOSS

AU - Pérez-Ràfols, Ignasi

AU - Miralda-Escudé, Jordi

AU - Lundgren, Britt

AU - Ge, Jian

AU - Petitjean, Patrick

AU - Schneider, Donald P.

AU - York, Donald G.

AU - Weaver, Benjamin A.

PY - 2015/1/1

Y1 - 2015/1/1

N2 - We present a measurement of the cross-correlation of MgII absorption and massive galaxies, using the Data Release (DR)11 main galaxy sample of the Baryon Oscillation Spectroscopic Survey (BOSS) of Sloan Digital Sky Survey III (SDSS-III; CMASS galaxies), and the DR7 quasar spectra of SDSS-II. The cross-correlation is measured by stacking quasar absorption spectra shifted to the redshift of galaxies that are within a certain impact parameter bin of the quasar, after dividing by a quasar continuum model. This results in an average MgII equivalent width as a function of impact parameter from a galaxy, ranging from 50 kpc to more than 10 Mpc in proper units, which includes all Mg II absorbers. We show that special care needs to be taken to use an unbiased quasar continuum estimator, to avoid systematic errors in the measurement of the mean stacked MgII equivalent width. The measured cross-correlation follows the expected shape of the galaxy correlation function, although measurement errors are large. We use the cross-correlation amplitude to derive the bias factor of MgII absorbers, finding bMg II = 2.33 ± 0.19, where the error accounts only for the statistical uncertainty in measuring the mean equivalent width. This bias factor is larger than that obtained in previous studies and may be affected by modelling uncertainties that we discuss, but if correct it suggests that MgII absorbers at redshift z ≃ 0.5 are spatially distributed on large scales similarly to the CMASS galaxies in BOSS.

AB - We present a measurement of the cross-correlation of MgII absorption and massive galaxies, using the Data Release (DR)11 main galaxy sample of the Baryon Oscillation Spectroscopic Survey (BOSS) of Sloan Digital Sky Survey III (SDSS-III; CMASS galaxies), and the DR7 quasar spectra of SDSS-II. The cross-correlation is measured by stacking quasar absorption spectra shifted to the redshift of galaxies that are within a certain impact parameter bin of the quasar, after dividing by a quasar continuum model. This results in an average MgII equivalent width as a function of impact parameter from a galaxy, ranging from 50 kpc to more than 10 Mpc in proper units, which includes all Mg II absorbers. We show that special care needs to be taken to use an unbiased quasar continuum estimator, to avoid systematic errors in the measurement of the mean stacked MgII equivalent width. The measured cross-correlation follows the expected shape of the galaxy correlation function, although measurement errors are large. We use the cross-correlation amplitude to derive the bias factor of MgII absorbers, finding bMg II = 2.33 ± 0.19, where the error accounts only for the statistical uncertainty in measuring the mean equivalent width. This bias factor is larger than that obtained in previous studies and may be affected by modelling uncertainties that we discuss, but if correct it suggests that MgII absorbers at redshift z ≃ 0.5 are spatially distributed on large scales similarly to the CMASS galaxies in BOSS.

UR - http://www.scopus.com/inward/record.url?scp=84942278725&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84942278725&partnerID=8YFLogxK

U2 - 10.1093/mnras/stu2645

DO - 10.1093/mnras/stu2645

M3 - Article

AN - SCOPUS:84942278725

VL - 447

SP - 2784

EP - 2802

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 3

ER -