The Low-z Intergalactic Medium. III. HI and Metal Absorbers at z<0.4

Abstract

We conduct an ultraviolet (HST and FUSE) spectroscopic survey of HI (Lyman lines) and seven metal ions (OVI, NV, CIV, CIII, SiIV, SiIII, FeIII) in the low-redshift intergalactic medium (IGM) at z<0.4. We analyzed 650 Lya absorbers over redshift pathlength Delta z=5.27, detecting numerous absorbers: 83 OVI systems, 39 CIII, 53 SiIII, 24 CIV, 24 NV, and so on. Our survey yields distributions in column density and estimates of the IGM baryon content and metallicities of C, N, O in the IGM. In the low-z IGM, we have accounted for ~40% of the baryons: 30% in the photoionized Lya forest and 10% in the (T=10^5-6 K) warm-hot intergalactic medium (WHIM) traced by OVI. Statistical metallicities of C, N, O ions are consistent with the canonical (z=0) value of 10% solar, with considerable scatter. Improved statistics for weak OVI absorbers allows us to estimate Omega_WHIM/Omega_b=0.073+-0.008 down to logN_OVI=13.4. NV absorption is well-correlated with OVI and both ions show similarly steep power-law indices dN/dz N^-beta with beta_OVI beta_NV 2 while beta_HI=1.7. We conclude that OVI and NV are reliable tracers of the portion of the WHIM at T=10^5-6 K. CIV may be present in both collisional and photoionized phases; N_CIV correlates poorly with both N_HI and N_OVI and beta_HI<beta_CIV<beta_OVI. The ions CIII, SiIII, and SiIV are well correlated with HI and show patterns typical of photoionization. Adjacent ion stages of the same element (CIII/IV and SiIII/IV) provide useful constraints on the photoionization parameter, logU=-1.5+-0.5. Comparison of SiIV and CIV with high-z surveys shows a modest increase in line density, consistent with increasing IGM metallicity at recent epochs.

Submitted to ApJ, 27 pages in ApJ format (figure and discussion added)

References in corpus (9)

• Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology
• Time-Dependent Ionization in Radiatively Cooling Gas
• The Search for the Missing Baryons at Low Redshift
• Physical Properties, Baryon Content, and Evolution of the LyαForest: New Insights from High Resolution Observations at z < 0.4
• On the Putative Detection of z>0 X-ray Absorption Features in the Spectrum of Markarian 421
• Metallicity and Ionization in High Velocity Cloud Complex C
• The UV spectrum of HS1700+6416 II. FUSE observations of the HeII Lyman alpha forest
• Probing the IGM/Galaxy Connection Toward PKS0405-123 III: The Galaxy Survey and Correlations with OVI Absorbers
• Confirming the Detection of an Intergalactic X-ray Absorber Toward PKS 2155-304

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