A Search for Oxygen in the Low-Density Lyman-alpha Forest Using the Sloan Digital Sky Survey

Details A Search for Oxygen in the Low-Density Lyman-alpha Forest Using the Sloan Digital Sky Survey A Search for Oxygen in the Low-Density Lyman-alpha Forest Using the Sloan Digital Sky Survey

2009-08-14

arxiv.org/abs/0908.2001v2

Astronomy and Astrophysics

Astrophysics

Cosmology and Extragalactic Astrophysics

12 pages, 9 figures. Accepted by ApJ (minor changes)

Scientific paper

We use 2167 Sloan Digital Sky Survey (SDSS) quasar spectra to search for low-density oxygen in the Intergalactic Medium (IGM). Oxygen absorption is detected on a pixel-by-pixel basis by its correlation with Lyman-alpha forest absorption. We have developed a novel Locally Calibrated Pixel (LCP) search method that uses adjacent regions of the spectrum to calibrate interlopers and spectral artifacts, which would otherwise limit the measurement of OVI absorption. Despite the challenges presented by searching for weak OVI within the Lyman-alpha forest in spectra of moderate resolution and signal-to-noise, we find a highly significant detection of absorption by oxygen at 2.7 < z < 3.2 (the null hypothesis has a chi^2=80 for 9 data points). We interpret our results using synthetic spectra generated from a lognormal density field assuming a mixed quasar-galaxy photoionizing background (Haardt & Madau 2001) and that it dominates the ionization fraction of detected OVI. The LCP search data can be fit by a constant metallicity model with [O/H] = -2.15_(-0.09)^(+0.07), but also by models in which low-density regions are unenriched and higher density regions have a higher metallicity. The density-dependent enrichment model by Aguirre et al. (2008) is also an acceptable fit. All our successful models have similar mass-weighted oxygen abundance, corresponding to [_MW] = -2.45+-0.06. This result can be used to find the cosmic oxygen density in the Lyman-alpha forest, Omega_(Oxy, IGM) = 1.4(+-0.2)x10^(-6) = 3x10^(-4) Omega_b. This is the tightest constraint on the mass-weighted mean oxygen abundance and the cosmic oxygen density in the Lyman-alpha forest to date and indicates that it contains approximately 16% of metals produced by star formation (Bouch\'e et al. 2008) up to z = 3.

Affiliated with

Also associated with

No associations

Rating

A Search for Oxygen in the Low-Density Lyman-alpha Forest Using the Sloan Digital Sky Survey does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with A Search for Oxygen in the Low-Density Lyman-alpha Forest Using the Sloan Digital Sky Survey, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A Search for Oxygen in the Low-Density Lyman-alpha Forest Using the Sloan Digital Sky Survey will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-272068