Abstract
view Abstract Citations (51) References (11) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Neutral Hydrogen Column Density Towards Q1937-1009 From the Unabsorbed Intrinsic Continuum in the Lyman-alpha Forest. Burles, Scott ; Tytler, David Abstract The absorption system at ζ=3.572 towards Q1937-1009 provides the best extragalactic measurement of the atomic deuterium to hydrogen ratio, D/H. We have obtained a new low-resolution, high signal-to-noise ratio (SNR) Keck spectrum to re-measure the total neutral hydrogen column density N(H I) using the amount of Lyman continuum absorption. We develop a new method to directly determine the intrinsic unabsorbed quasar continuum from low-resolution spectra of the Lyα forest for the first time. We use three types of spectra to measure N( H I): (1) A wide slit spectrum for flux calibration, (2) a high-resolution spectrum to determine the unabsorbed continuum between Lyα forest lines, and (3) a high SNR spectrum to measure the residual flux below the Lyman limit. We measure log[N(H I)]=17.86±0.02 cm-2, which is reliable because N(H I) is fully specified by the data. This result is consistent with the N(H I) measured by Tytler et al. (1996, Nature, 381, 207) from the Lyman series absorption lines, but not with absorption models proposed by Wampler (1996, Nature, 383, 308) nor estimates of the total N(H I) by Songaila et al. (1997, Nature, 385, 137), both of which suggested lower N(H I) and higher D/H. The Wampler models predict abundant flux below the Lyman limit which is absent from both our old and new spectra, taken with different instruments. The new Keck data is consistent with the data presented by Songaila et al. (1997). The results differ due to the different methods of analysis, and our measurement of the QSO continuum does not agree with the continuum models assumed by Songaila et al. Publication: The Astronomical Journal Pub Date: October 1997 DOI: 10.1086/118566 arXiv: arXiv:astro-ph/9707176 Bibcode: 1997AJ....114.1330B Keywords: QUASARS: ABSORPTION LINE; GALAXIES: ABUNDANCES; Astrophysics E-Print: 15 pages, 6 figures, To appear in the Astronomical Journal in October 1997 full text sources arXiv | ADS | data products SIMBAD (2) NED (2)
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