Carma CO observations of three extremely metal-poor, star-forming galaxies

Steven R. Warren; Edward Molter; John M. Cannon; Alberto D. Bolatto; Elizabeth A.K. Adams; Elijah Z. Bernstein-Cooper; Riccardo Giovanelli; Martha P. Haynes; Rodrigo Herrera-Camus; Katie Jameson; Kristen B.W. McQuinn; Katherine L. Rhode; John J. Salzer; Evan D. Skillman

doi:10.1088/0004-637X/814/1/30

Carma CO observations of three extremely metal-poor, star-forming galaxies

Steven R. Warren, Edward Molter, John M. Cannon, Alberto D. Bolatto, Elizabeth A.K. Adams, Elijah Z. Bernstein-Cooper, Riccardo Giovanelli, Martha P. Haynes, Rodrigo Herrera-Camus, Katie Jameson, Kristen B.W. McQuinn, Katherine L. Rhode, John J. Salzer, Evan D. Skillman

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8 Citations (Scopus)

Abstract

We present sensitive CO (J = 1 0) emission line observations of the three metal-poor dwarf irregular galaxies Leo P (Z ∼ 3% Z_o), Sextans A (Z ∼ 7.5% Z_o), and Sextans B (Z ∼ 7.5% Z_o), all obtained with the Combined Array for Millimeter-wave Astronomy interferometer. While no CO emission was detected, the proximity of the three systems allows us to place very stringent (4σ) upper limits on the CO luminosity (L_CO) in these metal-poor galaxies. We find the CO luminosities to be L_CO < 2900 K km s^-1 pc² for Leo P, L_CO < 12,400 K km s^-1 pc² for Sextans A, and L_CO < 9700 K km s^-1 pc² for Sextans B. Comparison of our results with recent observational estimates of the factor for converting between L_CO and the mass of molecular hydrogen, as well as theoretical models, provides further evidence that either the CO-to-H₂ conversion factor increases sharply as metallicity decreases, or that stars are forming in these three galaxies very efficiently, requiring little molecular hydrogen.

Original language	English
Article number	30
Journal	Astrophysical Journal
Volume	814
Issue number	1
DOIs	https://doi.org/10.1088/0004-637X/814/1/30
Publication status	Published - 20 Nov 2015
Externally published	Yes

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Warren, S. R., Molter, E., Cannon, J. M., Bolatto, A. D., Adams, E. A. K., Bernstein-Cooper, E. Z., Giovanelli, R., Haynes, M. P., Herrera-Camus, R., Jameson, K., McQuinn, K. B. W., Rhode, K. L., Salzer, J. J., & Skillman, E. D. (2015). Carma CO observations of three extremely metal-poor, star-forming galaxies. Astrophysical Journal, 814(1), Article 30. https://doi.org/10.1088/0004-637X/814/1/30

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title = "Carma CO observations of three extremely metal-poor, star-forming galaxies",

abstract = "We present sensitive CO (J = 1 0) emission line observations of the three metal-poor dwarf irregular galaxies Leo P (Z ∼ 3% Zo), Sextans A (Z ∼ 7.5% Zo), and Sextans B (Z ∼ 7.5% Zo), all obtained with the Combined Array for Millimeter-wave Astronomy interferometer. While no CO emission was detected, the proximity of the three systems allows us to place very stringent (4σ) upper limits on the CO luminosity (LCO) in these metal-poor galaxies. We find the CO luminosities to be LCO < 2900 K km s-1 pc2 for Leo P, LCO < 12,400 K km s-1 pc2 for Sextans A, and LCO < 9700 K km s-1 pc2 for Sextans B. Comparison of our results with recent observational estimates of the factor for converting between LCO and the mass of molecular hydrogen, as well as theoretical models, provides further evidence that either the CO-to-H2 conversion factor increases sharply as metallicity decreases, or that stars are forming in these three galaxies very efficiently, requiring little molecular hydrogen.",

keywords = "ISM: molecules, galaxies: ISM, galaxies: individual (Leo P, Sextans A, Sextans B)",

author = "Warren, {Steven R.} and Edward Molter and Cannon, {John M.} and Bolatto, {Alberto D.} and Adams, {Elizabeth A.K.} and Bernstein-Cooper, {Elijah Z.} and Riccardo Giovanelli and Haynes, {Martha P.} and Rodrigo Herrera-Camus and Katie Jameson and McQuinn, {Kristen B.W.} and Rhode, {Katherine L.} and Salzer, {John J.} and Skillman, {Evan D.}",

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doi = "10.1088/0004-637X/814/1/30",

language = "English",

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journal = "Astrophysical Journal",

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TY - JOUR

T1 - Carma CO observations of three extremely metal-poor, star-forming galaxies

AU - Warren, Steven R.

AU - Molter, Edward

AU - Cannon, John M.

AU - Bolatto, Alberto D.

AU - Adams, Elizabeth A.K.

AU - Bernstein-Cooper, Elijah Z.

AU - Giovanelli, Riccardo

AU - Haynes, Martha P.

AU - Herrera-Camus, Rodrigo

AU - Jameson, Katie

AU - McQuinn, Kristen B.W.

AU - Rhode, Katherine L.

AU - Salzer, John J.

AU - Skillman, Evan D.

PY - 2015/11/20

Y1 - 2015/11/20

N2 - We present sensitive CO (J = 1 0) emission line observations of the three metal-poor dwarf irregular galaxies Leo P (Z ∼ 3% Zo), Sextans A (Z ∼ 7.5% Zo), and Sextans B (Z ∼ 7.5% Zo), all obtained with the Combined Array for Millimeter-wave Astronomy interferometer. While no CO emission was detected, the proximity of the three systems allows us to place very stringent (4σ) upper limits on the CO luminosity (LCO) in these metal-poor galaxies. We find the CO luminosities to be LCO < 2900 K km s-1 pc2 for Leo P, LCO < 12,400 K km s-1 pc2 for Sextans A, and LCO < 9700 K km s-1 pc2 for Sextans B. Comparison of our results with recent observational estimates of the factor for converting between LCO and the mass of molecular hydrogen, as well as theoretical models, provides further evidence that either the CO-to-H2 conversion factor increases sharply as metallicity decreases, or that stars are forming in these three galaxies very efficiently, requiring little molecular hydrogen.

AB - We present sensitive CO (J = 1 0) emission line observations of the three metal-poor dwarf irregular galaxies Leo P (Z ∼ 3% Zo), Sextans A (Z ∼ 7.5% Zo), and Sextans B (Z ∼ 7.5% Zo), all obtained with the Combined Array for Millimeter-wave Astronomy interferometer. While no CO emission was detected, the proximity of the three systems allows us to place very stringent (4σ) upper limits on the CO luminosity (LCO) in these metal-poor galaxies. We find the CO luminosities to be LCO < 2900 K km s-1 pc2 for Leo P, LCO < 12,400 K km s-1 pc2 for Sextans A, and LCO < 9700 K km s-1 pc2 for Sextans B. Comparison of our results with recent observational estimates of the factor for converting between LCO and the mass of molecular hydrogen, as well as theoretical models, provides further evidence that either the CO-to-H2 conversion factor increases sharply as metallicity decreases, or that stars are forming in these three galaxies very efficiently, requiring little molecular hydrogen.

KW - ISM: molecules

KW - galaxies: ISM

KW - galaxies: individual (Leo P, Sextans A, Sextans B)

UR - http://www.scopus.com/inward/record.url?scp=84948662063&partnerID=8YFLogxK

U2 - 10.1088/0004-637X/814/1/30

DO - 10.1088/0004-637X/814/1/30

M3 - Article

SN - 0004-637X

VL - 814

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1

M1 - 30

ER -

Carma CO observations of three extremely metal-poor, star-forming galaxies

Abstract

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