Starburst-driven galactic winds — I. Energetics and intrinsic X-ray emission

By D. Strickland, I. Stevens. 2000

330 citations recorded by the source corpus.

Starburst-driven galactic winds are responsible for the transport of mass, in particular metal-enriched gas, and energy out of galaxies and into the intergalactic medium. These outflows directly affect the chemical evolution of galaxies, and heat and enrich the intergalactic and intercluster medium. Currently, several basic problems preclude quantitative measurements of the impact of galactic winds: the unknown filling factors of, in particular, the soft X-ray-emitting gas prevent accurate measurements of densities, masses and energy content; multiphase temperature distributions of unknown complexity bias X-ray-determined abundances; unknown amounts of energy and mass may reside in hard to observe T∼105 K and T∼107.5 K phases; and the relative balance of thermal versus kinetic energy in galactic winds is not known. In an effort to address these problems, we perform an extensive hydrodynamical parameter study of starburst-driven galactic winds, motivated by the latest observation data on the best-studied starburst galaxy M82. We study how the wind dynamics, morphology and X-ray emission depend on the ISM distribution of the host galaxy, the starburst star formation history and strength, and the presence and distribution of mass-loading by dense clouds. We also investigate and discuss the influence of finite numerical resolution on the results of these simulations. We find that the soft X-ray emission from galactic winds comes from low filling factor (η≲2 per cent) gas, which contains only a small fraction (≲10 per cent) of the mass and energy of the wind, irrespective of whether the wind models are strongly mass-loaded or not. X-ray observations of galactic winds do not directly probe the gas that contains the majority of the energy, mass or metal-enriched gas in the outflow. X-ray emission comes from a complex phase-continuum of gas, covering a wide range of different temperatures and densities. No distinct phases, as are commonly assumed when fitting X-ray spectra, are seen in our models. Estimates of the properties of the hot gas in starburst galaxies based on fitting simple spectral models to existing X-ray spectra should be treated with extreme suspicion. The majority of the thermal and kinetic energy of these winds is in a volume-filling hot, T∼107 K, component which is extremely difficult to probe observationally because of its low density and hence low emissivity. Most of the total energy is in the kinetic energy of this hot gas, a factor that must be taken into account when attempting to constrain wind energetics observationally. We also find that galactic winds are efficient at transporting large amounts of energy out of the host galaxy, in contrast to their inefficiency at transporting mass out of star-forming galaxies.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/a9c7e7f31c581d57de26e7213f4fd6d4f7d15a68

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Citations in the corpus

What Shapes the Luminosity Function of Galaxies? (2003, background): “In addition, the effectiveness with which the gas needs to be reheated seems excessive compared to observations of galactic outflows (Martin 1999) and to what is seen in simulations of this process in individual galaxies (Strickland & Stevens 2000).”
Three-Dimensional Simulations of a Starburst-driven Galactic Wind (2008, methodology): “Over the past few decades, numerous simulations have been made of starburst-driven winds (Tomisaka & Ikeuchi 1988; Tomisaka & Bregman 1993; Suchkov et al. 1994, 1996; D’Ercole &Brighenti 1999; Tenorio-Tagle&Muñoz-Tuñón 1998; Strickland & Stevens 2000; Tenorio-Tagle et al. 2003).”
Cosmic ray driven outflows in global galaxy disc models (2013, background): “In this model, diffuse, hard X-ray emitting gas at ∼107 K fills the majority of the volume, acting like a piston to sweep up a shell of denser gas (Chevalier & Clegg 1985; Strickland & Stevens 2000).”
Magnetic Fields in Starburst Galaxies and the Origin of the FIR-Radio Correlation (2006, background): “We note that in several simulations of galactic winds (e.g., Strickland & Stevens 2000), most of the X-ray emission is due to in situ shocks, which are also likely to be sites of particle acceleration.”
An XMM-Newton hard X-ray survey of ultraluminous infrared galaxies (2003, background): “According to the study by Strickland & Stevens (2000), the soft X-ray emission from SB-driven Galactic winds comes from a low filling factor ( 2 per cent) gas, which contains only a small fraction ( 10 per cent) of the mass and energy of the wind.”
Rest-Frame Ultraviolet Spectra of z ∼ 3 Lyman Break Galaxies (2003, methodology): “Also, the hydrodynamics of different phases of the outflowing ISM have been modeled numerically (Strickland & Stevens 2000).”
MOMENTUM INJECTION BY SUPERNOVAE IN THE INTERSTELLAR MEDIUM (2014, background): “The hot gas produced by SNRs is important because it may be able to escape the galaxy’s gravitational potential and drive a wind (e.g., Chevalier & Clegg 1985; Strickland & Stevens 2000).”
Multiphase High-Velocity Clouds toward HE 0226–4110 and PG 0953+414 (2005, background): “O vi–containing outflows are predicted by hydrodynamic simulations of galaxy winds (Mac Low & Ferrara 1999; Strickland & Stevens 2000) and have been detected in starburst galaxies NGC 1705 (Heckman et al. 2001) and NGC 625 (Cannon et al. 2005).”
Chandra Observations of NGC 253: New Insights into the Nature of Starburst-driven Superwinds (2000, neutral): “Further out in the wind, the dense gas in the outÑow probably exists as isolated dense clumps and clouds dragged out of the disk (as seen in hydrodynamical simulations ; e.g., Strickland & Stevens 2000).”
GIANT GAMMA-RAY BUBBLES FROM FERMI-LAT: ACTIVE GALACTIC NUCLEUS ACTIVITY OR BIPOLAR GALACTIC WIND? (2010, background): “Strickland & Stevens (2000) discussed the spatial structure in detail in X-ray.”
Mapping Large-Scale Gaseous Outflows in Ultraluminous Galaxies with Keck II ESI Spectra: Variations in Outflow Velocity with Galactic Mass (2004, background): “…by conditions in the highest density regions of hot component and do not necessarily reveal the hottest (lowest density) regions of the hot outflow (Strickland & Stevens 2000), but they do show that most of the shock heated mass can escape from dwarf galaxies with velocities less than 130 km s−1…”
A High Spatial Resolution X-Ray and Hα Study of Hot Gas in the Halos of Star-forming Disk Galaxies. II. Quantifying Supernova Feedback (2003, methodology): “Note that hydrodynamical simulations demonstrate that the expansion of a wind-blown bubble or superbubble is relatively insensitive to the spatial distribution of the energy injection within it (e.g., Strickland & Stevens 1998, 2000), for the reasons discussed by Mac Low & McCray (1988).”
The enrichment of the intergalactic medium with adiabatic feedback – I. Metal cooling and metal diffusion (2009, background): “Although detailed hydrodynamical simulations of the interstellar medium (ISM) in galaxies (e.g,, Mac Low & Ferrara 1999; Strickland & Stevens 2000; Williams & Dyson 2002) have been able to generate galactic outflows and have explored various properties of winds and the gas dynamics in different…”
Jet- and Wind-driven Ionized Outflows in the Superbubble and Star-forming Disk of NGC 3079 (2001, methodology): “Unfortunately, Strickland & Stevens (2000) have demonstrated by simulation that the superbubble dynamics are likely to remain poorly constrained because gas that emits soft X-rays has small Ðlling factor compared to the shocked wind (which at K isZ108.”
New Observations of the Interstellar Medium in the Lyman Break Galaxy MS 1512–cB58 (2001, background): “In an alternative scenario (see, for example, Strickland & Stevens 2000), the absorption arises within the cavity (filled with T 107 K gas, which is hard to observe directly) from fragments of the ambient ISM ablated by the hot gas.”
Chandra Observations of “The Antennae” Galaxies (NGC 4038/4039). III. X-Ray Properties and Multiwavelength Associations of the X-Ray Source Population (2002, methodology): “The fit with a PO+RS model results in a temperature of kT 0:8 keV (Table 7 of Paper II), which could be consistent with thermal emission by a supernova-driven superwind (e.g., Strickland & Stevens 2000).”
M82-F: a doomed super star cluster? (2001, background): “Again more modern approaches suggest that a normal IMF might be sufficient (Strickland & Stevens 2000).”
THREE-DIMENSIONAL INTEGRAL FIELD OBSERVATIONS OF 10 GALACTIC WINDS. I. EXTENDED PHASE (≳10 Myr) OF MASS/ENERGY INJECTION BEFORE THE WIND BLOWS (2010, background): “As noted by others (e.g. Chevalier & Clegg 1985), the ejecta ultimately thermalizes the diffuse material which escapes as a wind; any shock heating of the denser medium escapes as infrared radiation (Strickland & Stevens 2000).”