ANGULAR MOMENTUM of DWARF GALAXIES

Kirsty M. Butler, Danail Obreschkow, Se Heon Oh

Research output: Contribution to journalArticle

12 Citations (Scopus)

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 languageEnglish
Article numberL4
Number of pages6
JournalAstrophysical Journal Letters
Volume834
Issue number1
DOIs
Publication statusPublished - 1 Jan 2017

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dwarf galaxies
angular momentum
irregular galaxies
stars
Space Infrared Telescope Facility
Very Large Array (VLA)
galactic evolution
spiral galaxies
stellar mass
baryons
kinematics
hydrogen
scaling

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Butler, Kirsty M. ; Obreschkow, Danail ; Oh, Se Heon. / ANGULAR MOMENTUM of DWARF GALAXIES. In: Astrophysical Journal Letters. 2017 ; Vol. 834, No. 1.
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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 journalArticle

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T1 - ANGULAR MOMENTUM of DWARF GALAXIES

AU - Butler, Kirsty M.

AU - Obreschkow, Danail

AU - Oh, Se Heon

PY - 2017/1/1

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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

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