THE COS-HALOS SURVEY: ORIGINS OF THE HIGHLY IONIZED CIRCUMGALACTIC MEDIUM OF STAR-FORMING GALAXIES

By J. Werk, J. Xavier Prochaska, S. Cantalupo, A. J. Fox, B. Oppenheimer, Jason Tumlinson, T. Tripp, N. Lehner, M. McQuinn. 2016

163 citations recorded by the source corpus.

The total contribution of diffuse halo gas to the galaxy baryon budget strongly depends on its dominant ionization state. In this paper, we address the physical conditions in the highly ionized circumgalactic medium (CGM) traced by absorption lines observed in COS-Halos spectra. We analyze the observed ionic column densities, absorption-line widths and relative velocities, along with the ratios of / for 39 fitted Voigt profile components of O vi. We compare these quantities with the predictions given by a wide range of ionization models. Photoionization models that include only extragalactic UV background radiation are ruled out; conservatively, the upper limits to / and measurements of imply unphysically large path lengths ≳100 kpc. Furthermore, very broad absorption (b > 40 km s−1) is a defining characteristic of the CGM of star-forming L* galaxies. We highlight two possible origins for the bulk of the observed : (1) highly structured gas clouds photoionized primarily by local high-energy sources or (2) gas radiatively cooling on large scales behind a supersonic wind. Approximately 20% of circumgalactic O vi does not align with any low-ionization state gas within ±50 km s−1 and is found only in halos with < 1012 . We suggest that this type of unmatched O vi absorption traces the hot corona itself at a characteristic temperature of K. We discuss the implications of these very distinct physical origins for the dynamical state, gas cooling rates, and total baryonic content of L* gaseous halos.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/1aaa4051d2b84f7bc3b12275ac1688b914f29577

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

1. E. Quataert
2. J. Xavier Prochaska
3. Jason Tumlinson
4. P. Hopkins
5. Molly Peeples
6. Jessica Werk
7. C. Faucher-Giguére
8. T. Thompson

In Instrumentation

1. Molly Peeples
2. Jason Tumlinson
3. J. Xavier Prochaska
4. Jessica Werk
5. E. Quataert
6. T. Thompson
7. John M. O’Meara
8. G. Worseck

Citations in the corpus

• The impact of star formation feedback on the circumgalactic medium (2016, background): “5) (Werk et al. 2016).”
• The COS-Halos Survey: Metallicities in the Low-redshift Circumgalactic Medium (2017, background): “…motivated to these ‘single phase’ models by the tight kinematic correspondence between the H I Lyman series and the lower ionization state gas (Werk et al. 2016) and because these models provide a good fit to the lower ionization state gas in the majority of cases (see also Haislmaier et…”
• Figuring Out Gas & Galaxies in Enzo (FOGGIE). I. Resolving Simulated Circumgalactic Absorption at 2 ≤ z ≤ 2.5 (2018, result): “This prediction is consistent with the COS-Halos data of L* galaxies at z∼0.25 (Werk et al. 2014, 2016; cf. Borthakur et al. 2016).”
• The Circumgalactic Medium (2017, background): “In general, CIE models require a very narrow range of temperature to reproduce the O vi observations, T = 105.3−5.6 K (Tumlinson et al. 2011; Werk et al. 2016).”