2021ApJ...916...81C

Query : 2021ApJ...916...81C

2021ApJ...916...81C - Astrophys. J., 916, 81-81 (2021/August-1)

A deeper look at DES dwarf galaxy candidates: Grus I and Indus II.

CANTU S.A., PACE A.B., MARSHALL J., STRIGARI L.E., CRNOJEVIC D., SIMON J.D., DRLICA-WAGNER A., BECHTOL K., MARTINEZ-VAZQUEZ C.E., SANTIAGO B., AMARA A., STRINGER K.M., DIEHL H.T., AGUENA M., ALLAM S., AVILA S., BROOKS D., CARNERO ROSELL A., CARRASCO KIND M., CARRETERO J., COSTANZI M., DA COSTA L.N., DE VICENTE J., DESAI S., DOEL P., EIFLER T.F., EVERETT S., FRIEMAN J., GARCIA-BELLIDO J., GAZTANAGA E., GRUEN D., GRUENDL R.A., GSCHWEND J., GUTIERREZ G., HINTON S.R., HOLLOWOOD D.L., HONSCHEID K., JAMES D.J., KUEHN K., MAIA M.A.G., MENANTEAU F., MIQUEL R., PALMESE A., PAZ-CHINCHON F., PLAZAS A.A., SANCHEZ E., SCARPINE V., SCHUBNELL M., SERRANO S., SEVILLA-NOARBE I., SMITH M., SOARES-SANTOS M., SUCHYTA E., SWANSON M.E.C., TARLE G., WALKER A.R., WILKINSON R.D. (The DES Collaboration)

Abstract (from CDS):

We present deep g- and r-band Magellan/Megacam photometry of two dwarf galaxy candidates discovered in the Dark Energy Survey (DES), Grus I and Indus II (DES J2038-4609). For the case of Grus I, we resolved the main sequence turn-off (MSTO) and ∼2 mags below it. The MSTO can be seen at g0 ∼ 24 with a photometric uncertainty of 0.03 mag. We show Grus I to be consistent with an old, metal-poor (∼13.3 Gyr, [Fe/H] ∼ -1.9) dwarf galaxy. We derive updated distance and structural parameters for Grus I using this deep, uniform, wide-field data set. We find an azimuthally-averaged halflight radius more than two times larger (∼151+21–31 pc; ∼4′ / . 16–0.74+0.54) and an absolute V-band magnitude ∼-4.1 that is ∼1 magnitude brighter than previous studies. We obtain updated distance, ellipticity, and centroid parameters that are in agreement with other studies within uncertainties. Although our photometry of Indus II is ∼2-3 magnitudes deeper than the DES Y1 public release, we find no coherent stellar population at its reported location. The original detection was located in an incomplete region of sky in the DES Y2Q1 data set and was flagged due to potential blue horizontal branch member stars. The best-fit isochrone parameters are physically inconsistent with both dwarf galaxies and globular clusters. We conclude that Indus II is likely a false positive, flagged due to a chance alignment of stars along the line of sight.

Abstract Copyright: © 2021. The American Astronomical Society. All rights reserved.

Journal keyword(s): Dwarf galaxies - Astronomy data analysis - Photometry - Galaxy properties - Bayesian statistics

VizieR on-line data: <Available at CDS (J/ApJ/916/81): table3.dat table4.dat>

Status at CDS : All or part of tables of objects will not be ingested in SIMBAD.

Simbad objects: 3

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Number of rows : 3
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 NAME Ind II G 20 38.9 -46 10           ~ 31 0
2 NAME Jhelum Stream St* 21 25 -45.1           ~ 40 0
3 NAME Grus I G 22 56 42.4 -50 09 48           ~ 126 0

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