CONSTRAINING STELLAR FEEDBACK: SHOCK-IONIZED GAS IN NEARBY STARBURST GALAXIES
- Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States)
- Department of Astronomy, University of Wisconsin-Madison, 475 North Charter Street, Madison, WI 53706 (United States)
- Physics Department, University of California, Santa Barbara, CA 93106-9530 (United States)
- University of Nottingham, School of Physics and Astronomy, Nottingham NG7 2RD (United Kingdom)
- Department of Physics and Astronomy, Texas A and M University, 4242 TAMU, College Station, TX 77843-4242 (United States)
We investigate the properties of feedback-driven shocks in eight nearby starburst galaxies using narrow-band imaging data from the Hubble Space Telescope. We identify the shock-ionized component via the line diagnostic diagram [O III] (λ5007)/Hβ versus [S II] (λλ6716, 6731) (or [N II] (λ6583))/Hα, applied to resolved regions 3-15 pc in size. We divide our sample into three sub-samples: sub-solar, solar, and super-solar, for consistent shock measurements. For the sub-solar sub-sample, we derive three scaling relations: (1) L{sub shock}∝SFR{sup 0.62}, (2) L{sub shock}∝Σ{sub SFR,{sub HL}} {sup 0.92}, and (3) L{sub shock}/L{sub tot}∝(L{sub H} /L{sub ☉,{sub H}}){sup –0.65}, where L{sub shock} is the Hα luminosity from shock-ionized gas, Σ{sub SFR,{sub HL}} the star formation rate (SFR) per unit half-light area, L{sub tot} the total Hα luminosity, and L{sub H} /L{sub ☉,{sub H}} the absolute H-band luminosity from the Two Micron All Sky Survey normalized to solar luminosity. The other two sub-samples do not have enough number statistics, but appear to follow the first scaling relation. The energy recovered indicates that the shocks from stellar feedback in our sample galaxies are fully radiative. If the scaling relations are applicable in general to stellar feedback, our results are similar to those by Hopkins et al. for galactic superwinds. This similarity should, however, be taken with caution at this point, as the underlying physics that enables the transition from radiative shocks to gas outflows in galaxies is still poorly understood.
- OSTI ID:
- 22270632
- Journal Information:
- Astrophysical Journal, Vol. 777, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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