Cosmological Evolution of Heavy Element and Molecular Hydrogen Abundances

Abstract

Spectroscopic observations of distant quasars have resulted in the detection of molecular hydrogen in intervening damped Lyman-alpha absorption clouds (DLAs). We use observations compiled from different experimental groups to show that the molecular hydrogen abundance exhibits a dramatic increase over a cosmological time period corresponding to 13% to 24% of the age of the universe. We also tentatively show that the heavy element abundances in the same gas clouds exhibit a faster and more well-defined cosmological evolution compared to the general DLA population over the same time baseline. We argue that this latter point is unsurprising, because the general DLA population arises in a wide variety of galaxy types and environments, and thus a spans broad range of ISM gas-phases and abundances at the same cosmic time. DLAs exhibiting H2 absorption may therefore circumvent this problem, efficiently identifying a narrower class of objects, and provide a more sensitive probe of cosmological chemical evolution.

5 pages, 2 figures. Accepted by MNRAS Letters. v2: Added table summarizing H2-bearing DLA properties, added figure showing [Fe/H] vs. redshift, added more discussion

References in corpus (9)

• The Age-Metallicity Relation of the Universe in Neutral Gas: The First 100 Damped Lya Systems
• The VLT-UVES survey for molecular hydrogen in high-redshift damped Lyman-alpha systems
• Molecular hydrogen formation in the interstellar medium
• Low-Redshift Damped Lyman Alpha Galaxies Toward the Quasars B2 0827+243, PKS 0952+179, PKS 1127-145, and PKS 1629+120
• A deep search for 21cm absorption in high redshift damped Lyman-$\alpha$ systems
• Metallicity Evolution of Damped Lyman-Alpha Galaxies
• Comparing gas-phase and grain-catalyzed H2 formation
• Detection of molecular hydrogen at z=1.15 toward HE 0515-4414
• The Chemical Uniformity of High z DLA Protogalaxies

Cited by in corpus (20)

• Molecular hydrogen in high-redshift Damped Lyman-alpha systems: The VLT/UVES database
• Dust-reddening and gravitational lensing of SDSS QSOs due to foreground damped Lyman-alpha systems
• Molecules in galaxies
• Discovery of a Primitive Damped Lyman alpha Absorber Near an X-ray Bright Galaxy Group in the Virgo Cluster
• A survey for redshifted molecular and atomic absorption lines - II. Associated HI, OH and millimetre lines in the z >~ 3 Parkes quarter-Jansky flat-spectrum sample
• A survey for redshifted molecular and atomic absorption lines I
• A Near-Solar Metallicity, Nitrogen-Deficient Lyman Limit Absorber Associated with two S0 Galaxies
• Spin temperatures and covering factors for HI 21-cm absorption in damped Lyman-alpha systems
• The connection between metallicity and metal-line kinematics in (sub-)damped Lyman-alpha systems
• Molecular hydrogen in damped Ly-alpha systems: clues to interstellar physics at high-redshift
• The star formation history of damped Lyman alpha absorbers
• The geometry effects of an expanding Universe on the detection of cool neutral gas at high redshift
• New searches for HI 21-cm in damped Lyman-alpha absorption systems
• Relationships between the HI 21-cm line strength, MgII equivalent width and metallicity in damped Lyman-alpha absorption systems
• A correlation between the HI 21-cm absorption strength and impact parameter in external galaxies
• On the absence of molecular absorption in high redshift millimetre-band searches
• Measuring Changes in the Fundamental Constants with Redshifted Radio Absorption Lines
• A search for damped Lyman-alpha systems towards radio-loud quasars I: The optical survey
• A possible connection between the spin temperature of damped Lyman-alpha absorption systems and star formation history
• Ionised carbon and galaxy activity