Dust Scattering and the Radiation Pressure Force in the M82 Superwind

Abstract

Radiation pressure on dust grains may be an important physical mechanism driving galaxy-wide superwinds in rapidly star-forming galaxies. We calculate the combined dust and gas Eddington ratio (Gamma) for the archetypal superwind of M82. By combining archival GALEX data, a standard dust model, Monte Carlo dust scattering calculations, and the Herschel map of the dust surface density distribution, the observed FUV/NUV surface brightness in the outflow constrains both the total UV luminosity escaping from the starburst along its minor axis (L_*, UV) and the flux-mean opacity, thus allowing a calculation of Gamma. We find that L_(*, UV) ~ 1-6*10^42 ergs s^-1, ~2-12 times greater than the UV luminosity observed from our line of sight. On a scale of 1-3 kpc above the plane of M82, we find that Gamma ~ 0.01 - 0.06. On smaller scales (~0.25-0.5 kpc), where the enclosed mass decreases, our calculation of L_(*, UV) implies that Gamma ~ 0.1 with factor of few uncertainties. Within the starburst itself, we estimate the single-scattering Eddington ratio to be of order unity. Thus, although radiation pressure is weak compared to gravity on kpc scales above the plane of M82, it may yet be important in launching the observed outflow. We discuss the primary uncertainties in our calculation, the sensitivity of Gamma to the dust grain size distribution, and the time evolution of the wind following M82's recent starburst episodes.

9 pages, 9 figures, pdflatex

References in corpus (4)

• The Dynamics of Radiation Pressure-Dominated HII Regions
• A survey of polarization in the JVAS/CLASS flat-spectrum radio source surveys: I. The data and catalogue production
• HST/STIS spectroscopy of the environment in the starburst core of M82
• The Star Formation History of the Disk of the Starburst galaxy M82

Cited by in corpus (15)

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• Sub-Eddington Star-Forming Regions are Super-Eddington: Momentum Driven Outflows from Supersonic Turbulence
• Radiation pressure driving of a dusty atmosphere
• Spectral shifting strongly constrains molecular cloud disruption by radiation pressure on dust
• Ultraviolet Halos Around Spiral Galaxies. I. Morphology
• The Observable Properties of Cool Winds from Galaxies, AGN, and Star Clusters. I. Theoretical Framework
• The Characteristic Momentum of Radiatively Cooling Energy-Driven Galactic Winds
• Cosmic Rays and Magnetic Fields in the Core and Halo of the Starburst M82: Implications for Galactic Wind Physics
• The observable properties of cool winds from galaxies, AGN, and star clusters -- II. 3D models for the multiphase wind of M82
• Spectropolarimetry of the superwind filaments of the starburst galaxy M82 II: kinematics of the dust surrounding the nuclear starburst
• Radiation pressure in galactic disks: stability, turbulence, and winds in the single-scattering limit
• Grain Physics and IR Dust Emission in AGN Environments
• Observational Constraints on Cool Gas Clouds in M82's Starburst-Driven Outflow
• Chemical evolution of galaxies with radiation-driven dust wind
• JWST Observations of Starbursts: Dust Processing in the M82 Superwind