Astronomy and Astrophysics – Astrophysics
Scientific paper
1994-10-05
Astronomy and Astrophysics
Astrophysics
uuencoded postscript file; 19 pages text; 7 figures upon request; Columbia preprint #550 ; to appear in the ApJ Feb 10, 1995
Scientific paper
10.1086/175248
In order to carry out a systematic and thorough measurement of the HI Gunn-Peterson effect at high redshift, a quantitatively testable and repeatable procedure, in particular, a robust statistical weighting technique, is developed. It is applied to an echelle spectrum of resolution 15 km s$^{-1}$ of PKS 1937-101 with z=3.787. A weighted intensity distribution which is derived overwhelmingly from pixels close to the continuum level in the Ly alpha forest region is constructed by the evaluation of how closely correlated each pixel is with its neighboring pixels. The merit of the distribution is its stronger and narrower peak compared to the unweighted, as well as its smaller dependence on uncertainty of strong absorption lines and noise spikes. By comparison to the weighted intensity distribution of synthetic Ly alpha forest spectrum with various chosen diffuse HI opacities, a chi square fit is performed. In addition to a weak line population with power law N_H distribution $\beta =1.7$ extrapolated down to 10$^{12}$ cm$^{-2}$, a best chi square fit requires a GP opacity of $0.115 \pm 0.025$ at average z=3.4 with estimation of the contribution from the variance of $\beta$. Although no evidence of more than 1-2\% error is seen in the continuum extrapolation, the possible systematic overestimation due to the slope can be as high as the level of the $\chi^2$ fit, which is investigated by splitting the \Lya forest region into subsamples to check the continuum drop's dependence on absorber redshift.
Crotts Arlin
Fang Yihu
No associations
LandOfFree
A New Method for Measuring the Hi Gunn-Peterson Effect at High Redshift 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 New Method for Measuring the Hi Gunn-Peterson Effect at High Redshift, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A New Method for Measuring the Hi Gunn-Peterson Effect at High Redshift will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-244220