Abstract
We present measurements of baryonic mass Mb and specific angular momentum (sAM) jb in 14 rotating dwarf Irregular (dIrr) galaxies from the LITTLE THINGS sample. These measurements, based on 21 cm kinematic data from the Very Large Array and stellar mass maps from the Spitzer Space Telescope, extend previous AM measurements by more than two orders of magnitude in Mb. The dwarf galaxies show systematically higher jb values than expected from the jb ∝ Mb 2/3 scaling of spiral galaxies, representative of a scale-free galaxy formation scenario. This offset can be explained by decreasing baryon mass fractions fM = Mb Mdyn (where Mdyn is the dynamical mass) with decreasing Mb (for Mb < 1011M⊙). We find that the sAM of neutral atomic hydrogen (H I) alone is about 2.5 times higher than that of the stars. The Mj relation of H I is significantly steeper than that of the stars, as a direct consequence of the systematic variation of the H I fraction with Mb. © 2016. The American Astronomical Society.
| Original language | English |
|---|---|
| Article number | L4 |
| Number of pages | 6 |
| Journal | Astrophysical Journal Letters |
| Volume | 834 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 1 Jan 2017 |
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ANGULAR MOMENTUM of DWARF GALAXIES. / Butler, Kirsty M.; Obreschkow, Danail; Oh, Se Heon.
In: Astrophysical Journal Letters, Vol. 834, No. 1, L4, 01.01.2017.Research output: Contribution to journal › Article
TY - JOUR
T1 - ANGULAR MOMENTUM of DWARF GALAXIES
AU - Butler, Kirsty M.
AU - Obreschkow, Danail
AU - Oh, Se Heon
PY - 2017/1/1
Y1 - 2017/1/1
N2 - We present measurements of baryonic mass Mb and specific angular momentum (sAM) jb in 14 rotating dwarf Irregular (dIrr) galaxies from the LITTLE THINGS sample. These measurements, based on 21 cm kinematic data from the Very Large Array and stellar mass maps from the Spitzer Space Telescope, extend previous AM measurements by more than two orders of magnitude in Mb. The dwarf galaxies show systematically higher jb values than expected from the jb ∝ Mb 2/3 scaling of spiral galaxies, representative of a scale-free galaxy formation scenario. This offset can be explained by decreasing baryon mass fractions fM = Mb Mdyn (where Mdyn is the dynamical mass) with decreasing Mb (for Mb < 1011M⊙). We find that the sAM of neutral atomic hydrogen (H I) alone is about 2.5 times higher than that of the stars. The Mj relation of H I is significantly steeper than that of the stars, as a direct consequence of the systematic variation of the H I fraction with Mb. © 2016. The American Astronomical Society.
AB - We present measurements of baryonic mass Mb and specific angular momentum (sAM) jb in 14 rotating dwarf Irregular (dIrr) galaxies from the LITTLE THINGS sample. These measurements, based on 21 cm kinematic data from the Very Large Array and stellar mass maps from the Spitzer Space Telescope, extend previous AM measurements by more than two orders of magnitude in Mb. The dwarf galaxies show systematically higher jb values than expected from the jb ∝ Mb 2/3 scaling of spiral galaxies, representative of a scale-free galaxy formation scenario. This offset can be explained by decreasing baryon mass fractions fM = Mb Mdyn (where Mdyn is the dynamical mass) with decreasing Mb (for Mb < 1011M⊙). We find that the sAM of neutral atomic hydrogen (H I) alone is about 2.5 times higher than that of the stars. The Mj relation of H I is significantly steeper than that of the stars, as a direct consequence of the systematic variation of the H I fraction with Mb. © 2016. The American Astronomical Society.
KW - galaxies: dwarf
KW - galaxies: fundamental parameters
KW - galaxies: ISM
KW - galaxies: kinematics and dynamics
KW - galaxies: structure
UR - http://www.scopus.com/inward/record.url?scp=85008938031&partnerID=8YFLogxK
U2 - 10.3847/2041-8213/834/1/L4
DO - 10.3847/2041-8213/834/1/L4
M3 - Article
VL - 834
JO - The Astrophysical Journal Letters
JF - The Astrophysical Journal Letters
SN - 2041-8205
IS - 1
M1 - L4
ER -