ANGULAR MOMENTUM of DWARF GALAXIES

Kirsty M. Butler; Danail Obreschkow; Se Heon Oh

doi:10.3847/2041-8213/834/1/L4

ANGULAR MOMENTUM of DWARF GALAXIES

Kirsty M. Butler, Danail Obreschkow, Se Heon Oh

International Centre for Radio Astronomy Research (ICRAR)

Research output: Contribution to journal › Article

14 Citations (Scopus)

Abstract

We present measurements of baryonic mass Mb and specific angular momentum (sAM) j_b 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 M_b. The dwarf galaxies show systematically higher jb values than expected from the j_b ∝ M_b ^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 = M_b 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 M_b. © 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	https://doi.org/10.3847/2041-8213/834/1/L4
Publication status	Published - 1 Jan 2017

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title = "ANGULAR MOMENTUM of DWARF GALAXIES",

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. {\textcopyright} 2016. The American Astronomical Society.",

keywords = "galaxies: dwarf, galaxies: fundamental parameters, galaxies: ISM, galaxies: kinematics and dynamics, galaxies: structure",

author = "Butler, {Kirsty M.} and Danail Obreschkow and Oh, {Se Heon}",

year = "2017",

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doi = "10.3847/2041-8213/834/1/L4",

language = "English",

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journal = "The Astrophysical Journal Letters",

issn = "2041-8205",

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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

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VL - 834

JO - The Astrophysical Journal Letters

JF - The Astrophysical Journal Letters

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