<SUP>13</SUP>CO/C<SUP>18</SUP>O Gradients across the Disks of Nearby Spiral Galaxies

DOI: 
10.3847/2041-8213/836/2/L29
Publication date: 
01/02/2017
Main author: 
Jiménez-Donaire, María J.
IAA authors: 
Kramer, Carsten
Authors: 
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;Schinnerer, Eva;Schruba, Andreas;Schuster, Karl;Sliwa, Kazimierz;Tomicic, Neven
Journal: 
The Astrophysical Journal
Refereed: 
Yes
Publication type: 
Article
Volume: 
836
Pages: 
L29
Abstract: 

We use the IRAM Large Program EMPIRE and new high-resolution ALMA data to measure <SUP>13</SUP>CO(1-0)/C<SUP>18</SUP>O(1-0) intensity ratios across nine nearby spiral galaxies. These isotopologues of <SUP>12</SUP>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</SUP>CO/C<SUP>18</SUP>O gradients across normal galaxies have been rare due to the faintness of these lines. We find a mean <SUP>13</SUP>CO/C<SUP>18</SUP>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</SUP>CO/C<SUP>18</SUP>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.

Database: 
ADS
SCOPUS
URL: 
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014348890&doi=10.3847%2f2041-8213%2f836%2f2%2fL29&partnerID=40&md5=2a81744a449bab90fa54326cd375fdc3
ADS Bibcode: 
2017ApJ...836L..29J
Keywords: 
galaxies: ISM;ISM: molecules;radio lines: galaxies;Astrophysics - Astrophysics of Galaxies