Journal article : Letter
An old stellar population or diffuse nebular continuum emission discovered in Green Pea galaxies
- Abstract:
- We use new Hubble Space Telescope (HST) images of nine Green Pea galaxies (GPGs) to study their resolved structure and color. The choice of filters, F555W and F850LP, together with the redshift of the galaxies (z ~ 0.25), minimizes the contribution of the nebular [O iii] and Hα emission lines to the broadband images. While these galaxies are typically very blue in color, our analysis reveals that it is only the dominant stellar clusters that are blue. Each GPG does clearly show the presence of at least one bright and compact star-forming region, but these are invariably superimposed on a more extended and lower surface brightness emission. Moreover, the colors of the star-forming regions are on average bluer than those of the diffuse emission, reaching up to 0.6 magnitudes bluer. Assuming that the diffuse and compact components have constant and single-burst star formation histories, respectively, the observed colors imply that the diffuse components (possibly the host galaxy of the star formation episode) have, on average, old stellar ages (>1 Gyr), while the star clusters are younger than 500 Myr. While a redder stellar component is perhaps the most plausible explanation for these results, the limitations of our current data set lead us to examine possible alternative mechanisms, particularly recombination emission processes, which are unusually prominent in systems with such strong line emission. With the available data, however, it is not possible to distinguish between these two interpretations. A substantial presence of old stars would indicate that the mechanisms allowing large escape fractions in these local galaxies may be different from those at play during the reionization epoch.
- Publication status:
- Published
- Peer review status:
- Peer reviewed
Actions
Access Document
- Files:
-
-
(Preview, Version of record, 920.9KB, Terms of use)
-
- Publisher copy:
- 10.3847/2041-8213/abf7cc
Authors
- Publisher:
- American Astronomical Society
- Journal:
- Astrophysical Journal Letters More from this journal
- Volume:
- 912
- Issue:
- 2
- Article number:
- L22
- Publication date:
- 2021-05-06
- Acceptance date:
- 2021-04-13
- DOI:
- EISSN:
-
2041-8213
- ISSN:
-
2041-8205
- Language:
-
English
- Keywords:
- Subtype:
-
Letter
- Pubs id:
-
1150408
- Local pid:
-
pubs:1150408
- Deposit date:
-
2021-06-28
Terms of use
- Copyright holder:
- Clarke et al.
- Copyright date:
- 2021
- Rights statement:
- © 2021. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
- Licence:
- CC Attribution (CC BY)
If you are the owner of this record, you can report an update to it here: Report update to this record