Supernova feedback and the hot gas filling fraction of the interstellar medium

Journal Article · Fri Nov 20 04:00:00 EST 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/814/1/4· OSTI ID:22879408

Li, Miao; Ostriker, Jeremiah P.; Bryan, Greg L. ^[1]; Cen, Renyue ^[2]; Naab, Thorsten ^[3]

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1. Department of Astronomy, Columbia University, 550 W120th Street, New York, NY 10027 (United States)
2. Department of Astrophysical Sciences, Princeton University, Peyton Hall, Princeton, NJ 08544 (United States)
3. Max-Planck Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85741 Garching (Germany)

Supernovae (SNe), the most energetic stellar feedback mechanism, are crucial for regulating the interstellar medium (ISM) and launching galactic winds. We explore how supernova remnants (SNRs) create a multiphase medium by performing three-dimentional hydrodynamical simulations at various SN rates, S, and ISM average densities, n-bar . The evolution of an SNR in a self-consistently generated three-phase ISM is qualitatively different from that in a uniform or a two-phase warm/cold medium. By traveling faster and further in the low-density hot phase, the domain of an SNR increases by >10{sup 2.5}. Varying n-bar and S, we find that a steady state can only be achieved when the hot gas volume fraction f{sub V,hot}≲0.6±0.1. Above that level, overlapping SNRs render connecting topology of the hot gas, and the ISM is subjected to thermal runaway. Photoelectric heating (PEH) has a surprisingly strong impact on f{sub V,hot}. For n-bar ≳3 cm{sup −3}, a reasonable PEH rate is able to suppress the thermal runaway. Overall, we determine the critical SN rate for the onset of thermal runaway to be S{sub crit}=200( n-bar /1 cm{sup −3}){sup k}(E{sub SN}/10{sup 51} erg){sup −1} kpc{sup −3} Myr{sup −1}, where k = (1.2, 2.7) for n-bar ⩽1 and >1 cm{sup −3}, respectively. We present a fitting formula of the ISM pressure P( n-bar ,S), which can be used as an effective equation of state in cosmological simulations. Despite the five orders of magnitude span of ( n-bar ,S), the average Mach number varies little: M ≈ 0.5 ± 0.2, 1.2 ± 0.3, and 2.3 ± 0.9 for the hot, warm, and cold phases, respectively.

• OSTI ID: 22879408
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 814; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United Kingdom
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
DENSITY
EQUATIONS OF STATE
LAUNCHING
MACH NUMBER
STEADY-STATE CONDITIONS
SUPERNOVA REMNANTS
SUPERNOVAE
TOPOLOGY
WIND