TY - JOUR
T1 - Global HI kinematics in dwarf galaxies
AU - Stilp, Adrienne M.
AU - Dalcanton, Julianne J.
AU - Warren, Steven R.
AU - Skillman, Evan
AU - Ott, Jürgen
AU - Koribalski, Bärbel
N1 - Copyright:
Copyright 2015 Elsevier B.V., All rights reserved.
PY - 2013/3/10
Y1 - 2013/3/10
N2 - H I line widths are typically interpreted as a measure of interstellar medium turbulence, which is potentially driven by star formation (SF). In an effort to better understand the possible connections between line widths and SF, we have characterized H I kinematics in a sample of nearby dwarf galaxies by co-adding line-of-sight spectra after removing the rotational velocity to produce average global H I line profiles. These "superprofiles" are composed of a central narrow peak (∼6-10 km s-1) with higher-velocity wings to either side that contain ∼10%-15% of the total flux. The superprofiles are all very similar, indicating a universal global H I profile for dwarf galaxies. We compare characteristics of the superprofiles to various galaxy properties, such as mass and measures of SF, with the assumption that the superprofile represents a turbulent peak with energetic wings to either side. We use these quantities to derive average scale heights for the sample galaxies. When comparing to physical properties, we find that the velocity dispersion of the central peak is correlated with 〈ΣHI 〉. The fraction of mass and characteristic velocity of the high-velocity wings are correlated with measures of SF, consistent with the picture that SF drives surrounding H I to higher velocities. While gravitational instabilities provide too little energy, the SF in the sample galaxies does provide enough energy through supernovae, with realistic estimates of the coupling efficiency, to produce the observed superprofiles.
AB - H I line widths are typically interpreted as a measure of interstellar medium turbulence, which is potentially driven by star formation (SF). In an effort to better understand the possible connections between line widths and SF, we have characterized H I kinematics in a sample of nearby dwarf galaxies by co-adding line-of-sight spectra after removing the rotational velocity to produce average global H I line profiles. These "superprofiles" are composed of a central narrow peak (∼6-10 km s-1) with higher-velocity wings to either side that contain ∼10%-15% of the total flux. The superprofiles are all very similar, indicating a universal global H I profile for dwarf galaxies. We compare characteristics of the superprofiles to various galaxy properties, such as mass and measures of SF, with the assumption that the superprofile represents a turbulent peak with energetic wings to either side. We use these quantities to derive average scale heights for the sample galaxies. When comparing to physical properties, we find that the velocity dispersion of the central peak is correlated with 〈ΣHI 〉. The fraction of mass and characteristic velocity of the high-velocity wings are correlated with measures of SF, consistent with the picture that SF drives surrounding H I to higher velocities. While gravitational instabilities provide too little energy, the SF in the sample galaxies does provide enough energy through supernovae, with realistic estimates of the coupling efficiency, to produce the observed superprofiles.
KW - ISM: kinematics and dynamics
KW - galaxies: ISM
KW - galaxies: dwarf
KW - galaxies: irregular
KW - galaxies: kinematics and dynamics
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U2 - 10.1088/0004-637X/765/2/136
DO - 10.1088/0004-637X/765/2/136
M3 - Article
AN - SCOPUS:84874990886
VL - 765
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 2
M1 - 136
ER -