THE COS-HALOS SURVEY: AN EMPIRICAL DESCRIPTION OF METAL-LINE ABSORPTION IN THE LOW-REDSHIFT CIRCUMGALACTIC MEDIUM

By Jessica Werk, J. Xavier Prochaska, C. Thom, Jason Tumlinson, T. Tripp, M. John, O’Meara, Molly Peeples. 2012

295 citations recorded by the source corpus.

We present the equivalent width and column density measurements for low and intermediate ionization states of the circumgalactic medium (CGM) surrounding 44 low-z, L ≈ L* galaxies drawn from the COS-Halos survey. These measurements are derived from far-UV transitions observed in HST/COS and Keck/HIRES spectra of background quasars within an impact parameter R < 160 kpc to the targeted galaxies. The data show significant metal-line absorption for 33 of the 44 galaxies, including quiescent systems, revealing the common occurrence of a cool (T ≈ 104–105 K), metal-enriched CGM. The detection rates and column densities derived for these metal lines decrease with increasing impact parameter, a trend we interpret as a declining metal surface density profile for the CGM. A comparison of the relative column densities of adjacent ionization states indicates that the gas is predominantly ionized. The large surface density in metals demands a large reservoir of metals and gas in the cool CGM (very conservatively, McoolCGM > 109 M☉), which likely traces a distinct density and/or temperature regime from the highly ionized CGM traced by O+5 absorption. The large dispersion in absorption strengths (including non-detections) suggests that the cool CGM traces a wide range of densities or a mix of local ionizing conditions. Lastly, the kinematics inferred from the metal-line profiles are consistent with the cool CGM being bound to the dark matter halos hosting the galaxies; this gas may serve as fuel for future star formation. Future work will leverage this data set to provide estimates on the mass, metallicity, dynamics, and origin of the cool CGM in low-z, L* galaxies.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/fe19b6d3b06a4447f89e41f24ee885667a4a1ef4

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

Citations in the corpus

THE COS-HALOS SURVEY: RATIONALE, DESIGN, AND A CENSUS OF CIRCUMGALACTIC NEUTRAL HYDROGEN (2013, methodology): “…survey so far include the Werk et al. (2012) compilation of galaxy spectroscopy, the Tumlinson et al. (2011a) study of O VI bimodality in galaxy halos, the Thom et al. (2012) study of H I in early type galaxies, and the Werk et al. (2013) empirical description of the CGM as seen in metal lines.”
THE COS-HALOS SURVEY: PHYSICAL CONDITIONS AND BARYONIC MASS IN THE LOW-REDSHIFT CIRCUMGALACTIC MEDIUM (2014, methodology): “With respect to the first assumption, Werk et al. (2013) has shown that the kinematic component structure of the low-ion and intermediate-ion absorption profiles is similar.”
The Circumgalactic Medium (2017, background): “…and/or collisionally ionized gas in a low-density medium at 104 - 105.5 K (e.g., Adelberger et al. 2003; Richter et al. 2004; Fox et al. 2005; Narayanan et al. 2010; Matejek & Simcoe 2012; Stocke et al. 2013; Werk et al. 2013; Savage et al. 2014; Lehner et al. 2014; Turner et al. 2015).”
A BUDGET AND ACCOUNTING OF METALS AT z ∼ 0: RESULTS FROM THE COS-HALOS SURVEY (2013, methodology): “This mass is consistent with the dust expected to be associated with the level of Mg II absorption seen in the COSHalos sample (Ménard et al. 2008; Ménard & Fukugita 2012; Werk et al. 2013).”
THE BIMODAL METALLICITY DISTRIBUTION OF THE COOL CIRCUMGALACTIC MEDIUM AT z ≲ 1 (2013, background): “…results (e.g., Stocke et al. 2010, 2013; Thom et al. 2011; Tripp et al. 2011; Tumlinson et al. 2011a; Kacprzak et al. 2012b; Churchill et al. 2012; Werk et al. 2013) signal a shift in our ability to characterize the properties of the CGM and have already provided new stringent empirical results…”
The SAMI Galaxy Survey: shocks and outflows in a normal star-forming galaxy (2014, background): “The metal-enriched outflows are very likely to supply the vast amount of heavy elements discovered in the circumgalactic medium (Tumlinson et al. 2011; Werk et al. 2013).”
THE COS-DWARFS SURVEY: THE CARBON RESERVOIR AROUND SUB-L* GALAXIES (2014, methodology): “For star-forming galaxies, the COS-Dwarfs data clearly show a trend between virial radius (Rvir) and CIV absorption strength, that is quite similar to that observed for Mg II absorption (e.g. Chen et al. 2010, Bordoloi et al. 2011, Werk et al. 2013).”
EVIDENCE FOR UBIQUITOUS COLLIMATED GALACTIC-SCALE OUTFLOWS ALONG THE STAR-FORMING SEQUENCE AT z ∼ 0.5 (2013, background): “…surrounding low-redshift, L∗ galaxies have already confirmed the ubiquitous presence of such extended gas reservoirs, and find that the mass of material is comparable to that contained within the host galaxy interstellar medium (ISM; Tumlinson et al. 2011; Prochaska et al. 2011b; Werk et al. 2013).”
THE COS-HALOS SURVEY: ORIGINS OF THE HIGHLY IONIZED CIRCUMGALACTIC MEDIUM OF STAR-FORMING GALAXIES (2016, methodology): “Table 3 of Werk et al. 2013 summarizes the constraints on the column densities for these three ions.10 Figure 2 illustrates the average absorption profiles of the sample of COS-Halos sightlines considered here.”