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Title: The morphology and structure of stellar populations in the Fornax dwarf spheroidal galaxy from Dark Energy Survey Data

Abstract

Using deep wide-field photometry three-year data (Y3) from the Dark Energy Survey (DES), we present a panoramic study of the Fornax dwarf spheroidal galaxy. The data presented here -- a small subset of the full survey -- uniformly covers a region of 25 square degrees centered on the galaxy to a depth of g ~ 23.5. We use this data to study the structural properties of Fornax, overall stellar population, and its member stars in different evolutionary phases. We also search for possible signs of tidal disturbance. Fornax is found to be significantly more spatially extended than what early studies suggested. No statistically significant distortions or signs of tidal disturbances were found down to a surface brightness limit of ~32.1 mag/arcsec^2. However, there are hints of shell-like features located ~30' - 40' from the center of Fornax that may be stellar debris from past merger events. We also find that intermediate age and young main-sequence populations show different orientation at the galaxy center and have many substructures. The deep DES Y3 data allows us to characterize the age of those substructures with great accuracy, both those previously known and those newly discovered in this work, on the basis of theirmore » color-magnitude diagram morphology. We find that the youngest overdensities are all found on the Eastern side of Fornax, where the Fornax field population itself is slightly younger than in the West. The high quality DES Y3 data reveals that Fornax has many rich structures, and provides insights into its complex formation history.« less

Authors:
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Contributing Org.:
DES
OSTI Identifier:
1487054
Report Number(s):
arXiv:1809.07801; FERMILAB-PUB-18-505-AE
1695120
DOE Contract Number:  
AC02-07CH11359
Resource Type:
Journal Article
Journal Name:
TBD
Additional Journal Information:
Journal Name: TBD
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS

Citation Formats

Wang, M. Y., and et al. The morphology and structure of stellar populations in the Fornax dwarf spheroidal galaxy from Dark Energy Survey Data. United States: N. p., 2018. Web.
Wang, M. Y., & et al. The morphology and structure of stellar populations in the Fornax dwarf spheroidal galaxy from Dark Energy Survey Data. United States.
Wang, M. Y., and et al. Thu . "The morphology and structure of stellar populations in the Fornax dwarf spheroidal galaxy from Dark Energy Survey Data". United States. https://www.osti.gov/servlets/purl/1487054.
@article{osti_1487054,
title = {The morphology and structure of stellar populations in the Fornax dwarf spheroidal galaxy from Dark Energy Survey Data},
author = {Wang, M. Y. and et al.},
abstractNote = {Using deep wide-field photometry three-year data (Y3) from the Dark Energy Survey (DES), we present a panoramic study of the Fornax dwarf spheroidal galaxy. The data presented here -- a small subset of the full survey -- uniformly covers a region of 25 square degrees centered on the galaxy to a depth of g ~ 23.5. We use this data to study the structural properties of Fornax, overall stellar population, and its member stars in different evolutionary phases. We also search for possible signs of tidal disturbance. Fornax is found to be significantly more spatially extended than what early studies suggested. No statistically significant distortions or signs of tidal disturbances were found down to a surface brightness limit of ~32.1 mag/arcsec^2. However, there are hints of shell-like features located ~30' - 40' from the center of Fornax that may be stellar debris from past merger events. We also find that intermediate age and young main-sequence populations show different orientation at the galaxy center and have many substructures. The deep DES Y3 data allows us to characterize the age of those substructures with great accuracy, both those previously known and those newly discovered in this work, on the basis of their color-magnitude diagram morphology. We find that the youngest overdensities are all found on the Eastern side of Fornax, where the Fornax field population itself is slightly younger than in the West. The high quality DES Y3 data reveals that Fornax has many rich structures, and provides insights into its complex formation history.},
doi = {},
journal = {TBD},
number = ,
volume = ,
place = {United States},
year = {2018},
month = {9}
}

Journal Article:

Figures / Tables:

Figure 1 Figure 1: The surface density profile for Fornax dSph galaxy with overlaid best-fitting exponential (blue dotted line), Plummer (purple dash line), Sersic (red dash-dotted line) and King models (green solid line). The data is binned in elliptical annuli using the best fit position angle and ellipticity ϵ= 0.31, and themore » fits were performed to the full unbinned data allowing all parameters to vary freely, as described in Section § 3. We note that our fits are derived excluding stars within 10 arcmin radius (shown with the grey band). Parameter values of the fits are provided in Table 1.« less

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