A Search for Correlations between Turbulence and Star Formation in LITTLE THINGS Dwarf Irregular Galaxies

Journal Article · Thu Apr 01 04:00:00 EDT 2021 · The Astronomical Journal (Online)

DOI:https://doi.org/10.3847/1538-3881/ABE1C0· OSTI ID:23159182

Hunter, Deidre A.; Archer, Haylee ^[1]; Elmegreen, Bruce G. ^[2]; Simpson, Caroline E. ^[3]; Cigan, Phil ^[4]

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1. Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States)
2. IBM T.J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, NY USA (United States)
3. Department of Physics, Florida International University, CP 204, 11200 SW 8th Street, Miami, FL 33199 (United States)
4. George Mason University, 4400 University Drive, Fairfax, VA 22030-4444 (United States)

Turbulence has the potential for creating gas density enhancements that initiate cloud and star formation (SF), and it can be generated locally by SF. To study the connection between turbulence and SF, we looked for relationships between SF traced by FUV images, and gas turbulence traced by kinetic energy density (KED) and velocity dispersion (v {sub disp}) in the LITTLE THINGS sample of nearby dIrr galaxies. We performed 2D cross-correlations between FUV and KED images, measured cross-correlations in annuli to produce correlation coefficients as a function of radius, and determined the cumulative distribution function of the cross-correlation value. We also plotted on a pixel-by-pixel basis the locally excess KED, v {sub disp}, and H i mass surface density, Σ{sub HI}, as determined from the respective values with the radial profiles subtracted, versus the excess SF rate density Σ{sub SFR}, for all regions with positive excess Σ{sub SFR}. We found that Σ{sub SFR} and KED are poorly correlated. The excess KED associated with SF implies a ∼0.5% efficiency for supernova energy to pump local H i turbulence on the scale of the resolution here, which is a factor of ∼2 too small for all of the turbulence on a galactic scale. The excess v {sub disp} in SF regions is also small, only ∼0.37 km s{sup −1}. The local excess in Σ{sub HI} corresponding to an excess in Σ{sub SFR} is consistent with a H i consumption time of ∼1.6 Gyr in the inner parts of the galaxies. The similarity between this timescale and the consumption time for CO implies that CO-dark molecular gas has comparable mass to H i in the inner disks.

• OSTI ID: 23159182
• Journal Information: The Astronomical Journal (Online), Journal Name: The Astronomical Journal (Online) Journal Issue: 4 Vol. 161; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
79 ASTRONOMY AND ASTROPHYSICS
CARBON MONOXIDE
CLOUDS
COSMIC RADIATION
DENSITY
DISTRIBUTION FUNCTIONS
DWARF STARS
ELECTRIC CHARGES
ENERGY DENSITY
GALAXIES
KINETIC ENERGY
KINETICS
RESOLUTION
SURFACES
TURBULENCE