2014/02/28 by Ignasi Pérez-Ràfols, Jordi Miralda‐Escudé, Jordi Miralda-Escudé +6 · 17 citations
Physics and Astronomy · #Amplitude #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Baryon #Correlation function (quantum field theory) #Emission spectrum #Equivalent width #Galaxies: Formation, Evolution, Phenomena #Galaxy #Impact parameter #Physics #Quasar #Redshift #Spectral line #Stellar, planetary, and galactic studies #astro-ph.CO #astro-ph.GA
paper · pdf · doi:10.1093/mnras/stu2645
published in Monthly Notices of the Royal Astronomical Society 447(3), 2784-2802 (Oxford University Press) · Accepted for publication to MNRAS. Accepted 2014 December 12. Received 2014 November 29; in original form 2014 February 6
arxiv created 2014/12/22 · openalex publication_date 2015/01/10 · arxiv updated 2015/06/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present a measurement of the cross-correlation of Mg ii 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 Mg ii 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 Mg ii 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 Mg ii absorbers, finding |b_\mathrmMg \small 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 Mg ii absorbers at redshift z ≃ 0.5 are spatially distributed on large scales similarly to the CMASS galaxies in BOSS.