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Title: KINEMATICS OF EXTREMELY METAL-POOR GALAXIES: EVIDENCE FOR STELLAR FEEDBACK

Abstract

The extremely metal-poor (XMP) galaxies analyzed in a previous paper have large star-forming regions with a metallicity lower than the rest of the galaxy. Such a chemical inhomogeneity reveals the external origin of the metal-poor gas fueling star formation, possibly indicating accretion from the cosmic web. This paper studies the kinematic properties of the ionized gas in these galaxies. Most XMPs have a rotation velocity around a few tens of km s{sup −1}. The star-forming regions appear to move coherently. The velocity is constant within each region, and the velocity dispersion sometimes increases within the star-forming clump toward the galaxy midpoint, suggesting inspiral motion toward the galaxy center. Other regions present a local maximum in velocity dispersion at their center, suggesting a moderate global expansion. The H α line wings show a number of faint emission features with amplitudes around a few per cent of the main H α component, and wavelength shifts between 100 and 400 km s{sup −1}. The components are often paired, so that red and blue emission features with similar amplitudes and shifts appear simultaneously. Assuming the faint emission to be produced by expanding shell-like structures, the inferred mass loading factor (mass loss rate divided by starmore » formation rate) exceeds 10. Since the expansion velocity far exceeds the rotational and turbulent velocities, the gas may eventually escape from the galaxy disk. The observed motions involve energies consistent with the kinetic energy released by individual core-collapse supernovae. Alternative explanations for the faint emission have been considered and discarded.« less

Authors:
; ; ;  [1];  [2];  [3];  [4];  [5]
  1. Instituto Astrofísica de Canarias, E-38200 La Laguna, Tenerife (Spain)
  2. IBM Research Division, T. J. Watson Research Center, Yorktown Heights, NY 10598 (United States)
  3. Department of Physics and Astronomy, Vassar College, Poughkeepsie, NY 12604 (United States)
  4. Instituto de Astrofísica de Andalucía, CSIC, Granada (Spain)
  5. School of Physics and Astronomy, University of St Andrews, St Andrews (United Kingdom)
Publication Date:
OSTI Identifier:
22661360
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 834; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BALMER LINES; EXPANSION; FEEDBACK; GALAXIES; KINETIC ENERGY; MASS TRANSFER; METALLICITY; METALS; ROTATION; STAR ACCRETION; STAR EVOLUTION; STELLAR WINDS; SUPERNOVAE; VELOCITY; WAVELENGTHS

Citation Formats

Olmo-García, A., Sánchez Almeida, J., Muñoz-Tuñón, C., Filho, M. E., Elmegreen, B. G., Elmegreen, D. M., Pérez-Montero, E., and Méndez-Abreu, J., E-mail: jos@iac.es. KINEMATICS OF EXTREMELY METAL-POOR GALAXIES: EVIDENCE FOR STELLAR FEEDBACK. United States: N. p., 2017. Web. doi:10.3847/1538-4357/834/2/181.
Olmo-García, A., Sánchez Almeida, J., Muñoz-Tuñón, C., Filho, M. E., Elmegreen, B. G., Elmegreen, D. M., Pérez-Montero, E., & Méndez-Abreu, J., E-mail: jos@iac.es. KINEMATICS OF EXTREMELY METAL-POOR GALAXIES: EVIDENCE FOR STELLAR FEEDBACK. United States. doi:10.3847/1538-4357/834/2/181.
Olmo-García, A., Sánchez Almeida, J., Muñoz-Tuñón, C., Filho, M. E., Elmegreen, B. G., Elmegreen, D. M., Pérez-Montero, E., and Méndez-Abreu, J., E-mail: jos@iac.es. Tue . "KINEMATICS OF EXTREMELY METAL-POOR GALAXIES: EVIDENCE FOR STELLAR FEEDBACK". United States. doi:10.3847/1538-4357/834/2/181.
@article{osti_22661360,
title = {KINEMATICS OF EXTREMELY METAL-POOR GALAXIES: EVIDENCE FOR STELLAR FEEDBACK},
author = {Olmo-García, A. and Sánchez Almeida, J. and Muñoz-Tuñón, C. and Filho, M. E. and Elmegreen, B. G. and Elmegreen, D. M. and Pérez-Montero, E. and Méndez-Abreu, J., E-mail: jos@iac.es},
abstractNote = {The extremely metal-poor (XMP) galaxies analyzed in a previous paper have large star-forming regions with a metallicity lower than the rest of the galaxy. Such a chemical inhomogeneity reveals the external origin of the metal-poor gas fueling star formation, possibly indicating accretion from the cosmic web. This paper studies the kinematic properties of the ionized gas in these galaxies. Most XMPs have a rotation velocity around a few tens of km s{sup −1}. The star-forming regions appear to move coherently. The velocity is constant within each region, and the velocity dispersion sometimes increases within the star-forming clump toward the galaxy midpoint, suggesting inspiral motion toward the galaxy center. Other regions present a local maximum in velocity dispersion at their center, suggesting a moderate global expansion. The H α line wings show a number of faint emission features with amplitudes around a few per cent of the main H α component, and wavelength shifts between 100 and 400 km s{sup −1}. The components are often paired, so that red and blue emission features with similar amplitudes and shifts appear simultaneously. Assuming the faint emission to be produced by expanding shell-like structures, the inferred mass loading factor (mass loss rate divided by star formation rate) exceeds 10. Since the expansion velocity far exceeds the rotational and turbulent velocities, the gas may eventually escape from the galaxy disk. The observed motions involve energies consistent with the kinetic energy released by individual core-collapse supernovae. Alternative explanations for the faint emission have been considered and discarded.},
doi = {10.3847/1538-4357/834/2/181},
journal = {Astrophysical Journal},
number = 2,
volume = 834,
place = {United States},
year = {Tue Jan 10 00:00:00 EST 2017},
month = {Tue Jan 10 00:00:00 EST 2017}
}
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