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Stellar Metallicities from DECam $$u$$-band Photometry: A Study of Milky Way Ultra-Faint Dwarf Galaxies

Journal Article · · Astrophys.J.
 [1];  [2];  [3];  [2];  [4];  [5];  [6];  [6]
  1. Chicago U.; Princeton U.
  2. Chicago U.; Chicago U., Astron. Astrophys. Ctr.; Chicago U., EFI; Chicago U., KICP
  3. Chicago U.; Chicago U., Astron. Astrophys. Ctr.; Chicago U., EFI; Chicago U., KICP; Fermilab
  4. U. Toronto, Dunlap Inst. Astron. Astrophys.; Toronto U., Astron. Dept.
  5. Chicago U.; Chicago U., Astron. Astrophys. Ctr.; Chicago U., EFI; Chicago U., KICP; Sao Paulo U., IAG
  6. Fermilab
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We conducted an in-depth analysis of candidate member stars located in the peripheries of three ultra-faint dwarf (UFD) galaxy satellites of the Milky Way: Boötes I (Boo1), Boötes II (Boo2), and Segue I (Seg1). Studying these peripheral stars has previously been difficult due to contamination from the Milky Way foreground. We used $$u$$-band photometry from the Dark Energy Camera (DECam) to derive metallicities to efficiently select UFD candidate member stars. This approach was validated on Boo1, where we identified both previously known and new candidate member stars beyond five half-light radii. We then applied a similar procedure to Boo2 and Seg1. Our findings hinted at evidence for tidal features in Boo1 and Seg1, with Boo1 having an elongation consistent with its proper motion and Seg1 showing some distant candidate stars, a few of which are along its elongation and proper motion. We find two Boo2 stars at large distances consistent with being candidate member stars. Using a foreground contamination rate derived from the \emph{Besan\c{c}on} Galaxy model, we ascribed purity estimates to each candidate member star. We recommend further spectroscopic studies on the newly identified high-purity members. Our technique offers promise for future endeavors to detect candidate member stars at large radii in other systems, leveraging metallicity-sensitive filters with the Legacy Survey of Space and Time and the new, narrow-band Ca HK filter on DECam.
Research Organization:
Chicago U.; Chicago U., Astron. Astrophys. Ctr.; Chicago U., EFI; Chicago U., KICP; Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Princeton U.; Sao Paulo U., IAG; Toronto U., Astron. Dept.; U. Toronto, Dunlap Inst. Astron. Astrophys.
Sponsoring Organization:
US Department of Energy
Grant/Contract Number:
89243024CSC000002; AC02-07CH11359
OSTI ID:
2563257
Report Number(s):
FERMILAB-PUB-24-1022-PPD; oai:inspirehep.net:2912591; arXiv:2404.08054
Journal Information:
Astrophys.J., Journal Name: Astrophys.J. Vol. 978
Country of Publication:
United States
Language:
English

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Related Subjects

79 ASTRONOMY AND ASTROPHYSICS