For refcode 2010ApJ...708..868C: Retrieve 69 NED objects in this reference. Please click here for ADS abstract
NED Abstract
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2010ApJ...708..868C
The Last EightBillion Years of Intergalactic C IV Evolution
Cooksey, Kathy L.; Thom, Christopher; Prochaska, J. Xavier; Chen, HsiaoWen
Abstract. We surveyed the Hubble Space Telescope UV spectra of 49
lowredshift quasars for z < 1 C IV candidates, relying solely on the
characteristic wavelength separation of the doublet. After consideration
of the defining traits of C IV doublets (e.g., consistent line profiles,
other associated transitions, etc.), we defined a sample of 38 definite
(group G = 1) and five likely (G = 2) doublets with rest equivalent widths
W_r_ for both lines detected at >= 3{sigma}_W_r_. We conducted Monte Carlo
completeness tests to measure the unblocked redshift ({DELTA}z) and
comoving path length ({DELTA}X) over which we were sensitive to C IV
doublets of a range of equivalent widths and column densities. The
absorber line density of (G = 1+2) doublets is dN_CIV_/dX= 4.1^+0.7^_0.6_
for log N(C^+3^) >= 13.2, and dN_CIV_/dX has not evolved significantly
since z = 5. The bestfit power law to the G = 1 frequency distribution of
column densities f(N(C^+3^)) {approx} k(N(C^+3^)/N_0_)^{alpha}^_N_ has
coefficient k = 0.67^+0.18^_0.16_ x 10^14^ cm^2^ and exponent {alpha}_
N_ = 1.50^+0.17^_0.19_, where N_0_ = 10^14^ cm^2^. Using the
powerlaw model of f(N(C^+3^)), we measured the C^+3^ mass density
relative to the critical density: {OMEGA}_C_^+3^= (6.20^+1.82^_1.52_) x
10^8^ for 13 <= log N(C^+3^) <= 15. This value is a 2.8 +/ 0.7 increase
in {OMEGA}_C_^+3^ compared to the errorweighted mean from several 1 < z <
5 surveys for C IV absorbers. A simple linear regression to {OMEGA}_C_^+3^
over the age of the universe indicates that {OMEGA}_C_^+3^ has slowly but
steadily increased from z = 5 > 0, with d{OMEGA}_C_^+3^/ dt_age = (0.42
+/ 0.2) x 10^8^ Gyr^1^.
Key words: intergalactic medium, quasars: absorption lines, techniques:
spectroscopic
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