The Origin of C IV Absorption Systems at Redshifts z < 1: Discovery of Extended C IV Envelopes around Galaxies

By Hsiao-Wen Chen, K. Lanzetta, J. Webb. 2001

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We report the discovery of extended C IV gaseous envelopes around galaxies of a wide range of luminosity and morphological type. First, we show that C IV absorption systems are strongly clustered around galaxies on velocity scales of v ≲ 250 km s-1 and impact parameter scales of ρ ≲ 100 h-1 kpc, but not on larger velocity or impact parameter scales. Next, adopting measurements of galaxy properties presented in previous papers (which include B-band luminosity, surface brightness, and disk-to-bulge ratio), we examine how properties of the C IV absorption systems depend on properties of the galaxies. On the basis of 14 galaxy and absorber pairs and 36 galaxies that do not produce corresponding C IV absorption lines to within sensitive upper limits, we find that: (1) Galaxies of a range of morphological type and luminosity appear to possess extended C IV gaseous envelopes of radius R ≈ 100 h-1 kpc, with abrupt boundaries between the C IV absorbing and nonabsorbing regions. (2) The extent of C IV-absorbing gas around galaxies scales with galaxy B-band luminosity as R ∝ L but does not depend strongly on galaxy surface brightness, redshift, or morphological type. (3) The covering factor of C IV clouds within ≈100 h-1 kpc of galaxies is nearly unity, but there is a large scatter in the mean number of clouds encountered along the line of sight. After scaling to the luminosity of an L* galaxy, we find that 13 of 14 galaxies of impact parameter ρ < 100 h-1 kpc are associated with corresponding C IV absorption lines, while only one of 36 galaxies of impact parameter ρ > 100 h-1 kpc are associated with corresponding C IV absorption lines. The most significant implication of the study is that galaxies of a wide range of luminosity and morphological type are surrounded by chemically enriched gas that extends for at least ≈100 h-1 kpc. We consider various scenarios that may have produced metals at large galactic distance and conclude that accreting satellites are most likely to be responsible for chemically enriched gas at large galactic distances to regular-looking galaxies.

Subfields: Astronomy and Astrophysics, Biophysics

View Paper: https://www.semanticscholar.org/paper/766a39759599522db667fe28c01798a523facb9f

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Citations in the corpus

The COS-Halos Survey: Metallicities in the Low-redshift Circumgalactic Medium (2017, background): “Enrichment of the cool CGM Detections of strong metal lines in ∼ L∗ galaxy halos demonstrate that the CGM is enriched in heavy elements (Bergeron 1986; Chen et al. 2001).”
THE COS-HALOS SURVEY: AN EMPIRICAL DESCRIPTION OF METAL-LINE ABSORPTION IN THE LOW-REDSHIFT CIRCUMGALACTIC MEDIUM (2012, background): “The obvious exception is Mg+, which has been extensively surveyed over the past several years (e.g., Barton & Cooke 2009; Chen et al. 2010), and to a lesser extent C+3 (not covered by this work), which is found to extend out to 150 kpc (Chen et al. 2001).”
THE COS-DWARFS SURVEY: THE CARBON RESERVOIR AROUND SUB-L* GALAXIES (2014, methodology): “Using HST Key Project data, Chen et al. (2001) characterized the CIV absorption profile around 50 z≈ 0.4 galaxies with background quasar lines of sight passing within 300 kpc of the host galaxies.”
AN EMPIRICAL CHARACTERIZATION OF EXTENDED COOL GAS AROUND GALAXIES USING Mg ii ABSORPTION FEATURES (2010, methodology): “…of Extended Cool Gas and Implications for the Baryon Content of Galactic Halos The presence of a finite extentRgasof Mg II absorbing gas is similar to what is found for extended C IV (Chen et al. 2001) and also for OVI absorbing gas recently published by Chen & Mulchaey (2009) around galaxies.”
CHARACTERIZING THE CIRCUMGALACTIC MEDIUM OF NEARBY GALAXIES WITH HST/COS AND HST/STIS ABSORPTION-LINE SPECTROSCOPY (2012, methodology): “Figure 9 shows a variation on the now-standard plot of impact parameter vs Lyα equivalent width first described by Lanzetta et al. (1995) and further investigated by Chen et al. (2001) and Chen & Mulchaey (2009).”
Gravitational quenching in massive galaxies and clusters by clumpy accretion (2007, background): “…clumps may be detected at high redshift as the high column density absorption systems in quasar spectra, such as Lyman limit and CIV systems (based on the model of Mo & Miralda-Escude 1996), which are observed to reside within the extended virial haloes of bright galaxies (Chen et al. 2001).”
Gaseous Galaxy Halos (2012, result): “This seems to be consistent with the extensive work at higher redshifts that measure covering fractions close to unity for C IV (z ∼ 0.5) and O VI (z > 0.1) within 100 kpc of star forming galaxies (Chen et al., 2001; Tumlinson et al., 2011; Chen & Mulchaey, 2009).”
PROBING THE INTERGALACTIC MEDIUM/GALAXY CONNECTION. V. ON THE ORIGIN OF Lyα AND O vi ABSORPTION AT z < 0.2 (2011, methodology): “In each case, the authors have reported a very high detection rate for galaxies within a few hundred kpc: Chen et al. (2001a) found positive detections for 29/31 of their predominantly L∗ galaxies to ρ = 250 h−172 kpc with W Lyα > 300mÅ and reported a sharp decline at larger impact parameter;…”
Mg II Absorption Systems in Sloan Digital Sky Survey QSO Spectra (2005, background): “Chen et al. (2001) find R eA ¼ 137 h 170 kpc for C iv absorbers, which may sample larger galactocentric radii.”