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Title: {sup 13}CO/C{sup 18}O Gradients across the Disks of Nearby Spiral Galaxies

Abstract

We use the IRAM Large Program EMPIRE and new high-resolution ALMA data to measure {sup 13}CO(1-0)/C{sup 18}O(1-0) intensity ratios across nine nearby spiral galaxies. These isotopologues of {sup 12}CO are typically optically thin across most of the area in galaxy disks, and this ratio allows us to gauge their relative abundance due to chemistry or stellar nucleosynthesis effects. Resolved {sup 13}CO/C{sup 18}O gradients across normal galaxies have been rare due to the faintness of these lines. We find a mean {sup 13}CO/C{sup 18}O ratio of 6.0 ± 0.9 for the central regions of our galaxies. This agrees well with results in the Milky Way, but differs from results for starburst galaxies (3.4 ± 0.9) and ultraluminous infrared galaxies (1.1 ± 0.4). In our sample, the {sup 13}CO/C{sup 18}O ratio consistently increases with increasing galactocentric radius and decreases with increasing star formation rate surface density. These trends could be explained if the isotopic abundances are altered by fractionation; the sense of the trends also agrees with those expected for carbon and oxygen isotopic abundance variations due to selective enrichment by massive stars.

Authors:
; ;  [1]; ;  [2];  [3];  [4];  [5];  [6];  [7];  [8]; ;  [9]; ; ;  [10];  [11]
  1. Institut für theoretische Astrophysik, Zentrum für Astronomie der Universität Heidelberg, Albert-Ueberle Str. 2, D-69120 Heidelberg (Germany)
  2. Department of Astronomy, The Ohio State University, 140 W 18th St, Columbus, OH 43210 (United States)
  3. Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia)
  4. Observatorio Astronómico Nacional, Alfonso XII 3, E-28014, Madrid (Spain)
  5. CNRS, IRAP, 9 Av. colonel Roche, BP 44346, F-31028 Toulouse cedex 4 (France)
  6. Instituto de Astrofísica de Andalucía IAA-CSIC, Glorieta de la Astronomía s/n, E-18008, Granada (Spain)
  7. Department of Physics, New Mexico Institute of Mining and Technology, 801 Leroy Pl, Soccoro, NM 87801 (United States)
  8. National Radio Astronomy Observatory, 520 Edgemont Rd, Charlottesville, VA 22903 (United States)
  9. Institut de Radioastronomie Millimétrique (IRAM), 300 Rue de la Piscine, F-38406 Saint Martin d’Hères (France)
  10. Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany)
  11. Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching (Germany)
Publication Date:
OSTI Identifier:
22654532
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 836; 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; ABUNDANCE; CARBON 13; CARBON MONOXIDE; DENSITY; FRACTIONATION; ISOTOPE RATIO; MILKY WAY; MOLECULES; NUCLEOSYNTHESIS; OXYGEN 18; RESOLUTION; STARS; SURFACES

Citation Formats

Jiménez-Donaire, María J., Cormier, Diane, Bigiel, Frank, Leroy, Adam K., Gallagher, Molly, Krumholz, Mark R., Usero, Antonio, Hughes, Annie, Kramer, Carsten, Meier, David, Murphy, Eric, Pety, Jérôme, Schuster, Karl, Schinnerer, Eva, Sliwa, Kazimierz, Tomicic, Neven, and Schruba, Andreas, E-mail: m.jimenez@zah.uni-heidelberg.de. {sup 13}CO/C{sup 18}O Gradients across the Disks of Nearby Spiral Galaxies. United States: N. p., 2017. Web. doi:10.3847/2041-8213/836/2/L29.
Jiménez-Donaire, María J., Cormier, Diane, Bigiel, Frank, Leroy, Adam K., Gallagher, Molly, Krumholz, Mark R., Usero, Antonio, Hughes, Annie, Kramer, Carsten, Meier, David, Murphy, Eric, Pety, Jérôme, Schuster, Karl, Schinnerer, Eva, Sliwa, Kazimierz, Tomicic, Neven, & Schruba, Andreas, E-mail: m.jimenez@zah.uni-heidelberg.de. {sup 13}CO/C{sup 18}O Gradients across the Disks of Nearby Spiral Galaxies. United States. doi:10.3847/2041-8213/836/2/L29.
Jiménez-Donaire, María J., Cormier, Diane, Bigiel, Frank, Leroy, Adam K., Gallagher, Molly, Krumholz, Mark R., Usero, Antonio, Hughes, Annie, Kramer, Carsten, Meier, David, Murphy, Eric, Pety, Jérôme, Schuster, Karl, Schinnerer, Eva, Sliwa, Kazimierz, Tomicic, Neven, and Schruba, Andreas, E-mail: m.jimenez@zah.uni-heidelberg.de. Mon . "{sup 13}CO/C{sup 18}O Gradients across the Disks of Nearby Spiral Galaxies". United States. doi:10.3847/2041-8213/836/2/L29.
@article{osti_22654532,
title = {{sup 13}CO/C{sup 18}O Gradients across the Disks of Nearby Spiral Galaxies},
author = {Jiménez-Donaire, María J. and Cormier, Diane and Bigiel, Frank and Leroy, Adam K. and Gallagher, Molly and Krumholz, Mark R. and Usero, Antonio and Hughes, Annie and Kramer, Carsten and Meier, David and Murphy, Eric and Pety, Jérôme and Schuster, Karl and Schinnerer, Eva and Sliwa, Kazimierz and Tomicic, Neven and Schruba, Andreas, E-mail: m.jimenez@zah.uni-heidelberg.de},
abstractNote = {We use the IRAM Large Program EMPIRE and new high-resolution ALMA data to measure {sup 13}CO(1-0)/C{sup 18}O(1-0) intensity ratios across nine nearby spiral galaxies. These isotopologues of {sup 12}CO are typically optically thin across most of the area in galaxy disks, and this ratio allows us to gauge their relative abundance due to chemistry or stellar nucleosynthesis effects. Resolved {sup 13}CO/C{sup 18}O gradients across normal galaxies have been rare due to the faintness of these lines. We find a mean {sup 13}CO/C{sup 18}O ratio of 6.0 ± 0.9 for the central regions of our galaxies. This agrees well with results in the Milky Way, but differs from results for starburst galaxies (3.4 ± 0.9) and ultraluminous infrared galaxies (1.1 ± 0.4). In our sample, the {sup 13}CO/C{sup 18}O ratio consistently increases with increasing galactocentric radius and decreases with increasing star formation rate surface density. These trends could be explained if the isotopic abundances are altered by fractionation; the sense of the trends also agrees with those expected for carbon and oxygen isotopic abundance variations due to selective enrichment by massive stars.},
doi = {10.3847/2041-8213/836/2/L29},
journal = {Astrophysical Journal Letters},
number = 2,
volume = 836,
place = {United States},
year = {Mon Feb 20 00:00:00 EST 2017},
month = {Mon Feb 20 00:00:00 EST 2017}
}