A Deeper Look at des Dwarf Galaxy Candidates: Grus i and Indus ii

Sarah A. Cantu; Andrew B. Pace; Jennifer Marshall; Louis E. Strigari; Denija Crnojevic; Joshua D. Simon; A. Drlica-Wagner; K. Bechtol; Clara E. Martínez-Vázquez; B. Santiago; A. Amara; K. M. Stringer; H. T. Diehl; M. Aguena; S. Allam; S. Avila; D. Brooks; A. Carnero Rosell; M. Carrasco Kind; J. Carretero; M. Costanzi; L. N. Da Costa; J. De Vicente; S. Desai; P. Doel; T. F. Eifler; S. Everett; J. Frieman; J. García-Bellido; E. Gaztanaga; D. Gruen; R. A. Gruendl; J. Gschwend; G. Gutierrez; S. R. Hinton; D. L. Hollowood; K. Honscheid; D. J. James; K. Kuehn; M. A.G. Maia; F. Menanteau; R. Miquel; A. Palmese; F. Paz-Chinchón; A. A. Plazas; E. Sanchez; V. Scarpine; M. Schubnell; S. Serrano; I. Sevilla-Noarbe; M. Smith; M. Soares-Santos; E. Suchyta; M. E.C. Swanson; G. Tarle; A. R. Walker; R. D. Wilkinson

doi:10.3847/1538-4357/ac0443

A Deeper Look at des Dwarf Galaxy Candidates: Grus i and Indus ii

Sarah A. Cantu, Andrew B. Pace, Jennifer Marshall, Louis E. Strigari, Denija Crnojevic, Joshua D. Simon, A. Drlica-Wagner, K. Bechtol, Clara E. Martínez-Vázquez, B. Santiago, A. Amara, K. M. Stringer, H. T. Diehl, M. Aguena, S. Allam, S. Avila, D. Brooks, A. Carnero Rosell, M. Carrasco Kind, J. CarreteroM. Costanzi, L. N. Da Costa, J. De Vicente, S. Desai, P. Doel, T. F. Eifler, S. Everett, J. Frieman, J. García-Bellido, E. Gaztanaga, D. Gruen, R. A. Gruendl, J. Gschwend, G. Gutierrez, S. R. Hinton, D. L. Hollowood, K. Honscheid, D. J. James, K. Kuehn, M. A.G. Maia, F. Menanteau, R. Miquel, A. Palmese, F. Paz-Chinchón, A. A. Plazas, E. Sanchez, V. Scarpine, M. Schubnell, S. Serrano, I. Sevilla-Noarbe, M. Smith, M. Soares-Santos, E. Suchyta, M. E.C. Swanson, G. Tarle, A. R. Walker, R. D. Wilkinson

Workflow Systems

Research output: Contribution to journal › Article › peer-review

15 Scopus citations

Abstract

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 g 0 ∼ 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.

Original language	English
Article number	81
Journal	Astrophysical Journal
Volume	916
Issue number	2
DOIs	https://doi.org/10.3847/1538-4357/ac0443
State	Published - Aug 1 2021

Access to Document

10.3847/1538-4357/ac0443

Cite this

Cantu, S. A., Pace, A. B., Marshall, J., Strigari, L. E., Crnojevic, D., Simon, J. D., Drlica-Wagner, A., Bechtol, K., Martínez-Vázquez, 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., ... Wilkinson, R. D. (2021). A Deeper Look at des Dwarf Galaxy Candidates: Grus i and Indus ii. Astrophysical Journal, 916(2), Article 81. https://doi.org/10.3847/1538-4357/ac0443

@article{471b7eaf8ae4409b92bf07cc97f9c6ec,

title = "A Deeper Look at des Dwarf Galaxy Candidates: Grus i and Indus ii",

abstract = "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 g 0 ∼ 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.",

author = "Cantu, {Sarah A.} and Pace, {Andrew B.} and Jennifer Marshall and Strigari, {Louis E.} and Denija Crnojevic and Simon, {Joshua D.} and A. Drlica-Wagner and K. Bechtol and Mart{\'i}nez-V{\'a}zquez, {Clara E.} and B. Santiago and A. Amara and Stringer, {K. M.} and Diehl, {H. T.} and M. Aguena and S. Allam and S. Avila and D. Brooks and {Carnero Rosell}, A. and {Carrasco Kind}, M. and J. Carretero and M. Costanzi and {Da Costa}, {L. N.} and {De Vicente}, J. and S. Desai and P. Doel and Eifler, {T. F.} and S. Everett and J. Frieman and J. Garc{\'i}a-Bellido and E. Gaztanaga and D. Gruen and Gruendl, {R. A.} and J. Gschwend and G. Gutierrez and Hinton, {S. R.} and Hollowood, {D. L.} and K. Honscheid and James, {D. J.} and K. Kuehn and Maia, {M. A.G.} and F. Menanteau and R. Miquel and A. Palmese and F. Paz-Chinch{\'o}n and Plazas, {A. A.} and E. Sanchez and V. Scarpine and M. Schubnell and S. Serrano and I. Sevilla-Noarbe and M. Smith and M. Soares-Santos and E. Suchyta and Swanson, {M. E.C.} and G. Tarle and Walker, {A. R.} and Wilkinson, {R. D.}",

year = "2021",

month = aug,

day = "1",

doi = "10.3847/1538-4357/ac0443",

language = "English",

volume = "916",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "American Astronomical Society",

number = "2",

}

Cantu, SA, Pace, AB, Marshall, J, Strigari, LE, Crnojevic, D, Simon, JD, Drlica-Wagner, A, Bechtol, K, Martínez-Vázquez, CE, Santiago, B, Amara, A, Stringer, KM, Diehl, HT, Aguena, M, Allam, S, Avila, S, Brooks, D, Carnero Rosell, A, Carrasco Kind, M, Carretero, J, Costanzi, M, Da Costa, LN, De Vicente, J, Desai, S, Doel, P, Eifler, TF, Everett, S, Frieman, J, García-Bellido, J, Gaztanaga, E, Gruen, D, Gruendl, RA, Gschwend, J, Gutierrez, G, Hinton, SR, Hollowood, DL, Honscheid, K, James, DJ, Kuehn, K, Maia, MAG, Menanteau, F, Miquel, R, Palmese, A, Paz-Chinchón, F, Plazas, AA, Sanchez, E, Scarpine, V, Schubnell, M, Serrano, S, Sevilla-Noarbe, I, Smith, M, Soares-Santos, M, Suchyta, E, Swanson, MEC, Tarle, G, Walker, AR & Wilkinson, RD 2021, 'A Deeper Look at des Dwarf Galaxy Candidates: Grus i and Indus ii', Astrophysical Journal, vol. 916, no. 2, 81. https://doi.org/10.3847/1538-4357/ac0443

TY - JOUR

T1 - A Deeper Look at des Dwarf Galaxy Candidates

T2 - Grus i and Indus ii

AU - Cantu, Sarah A.

AU - Pace, Andrew B.

AU - Marshall, Jennifer

AU - Strigari, Louis E.

AU - Crnojevic, Denija

AU - Simon, Joshua D.

AU - Drlica-Wagner, A.

AU - Bechtol, K.

AU - Martínez-Vázquez, Clara E.

AU - Santiago, B.

AU - Amara, A.

AU - Stringer, K. M.

AU - Diehl, H. T.

AU - Aguena, M.

AU - Allam, S.

AU - Avila, S.

AU - Brooks, D.

AU - Carnero Rosell, A.

AU - Carrasco Kind, M.

AU - Carretero, J.

AU - Costanzi, M.

AU - Da Costa, L. N.

AU - De Vicente, J.

AU - Desai, S.

AU - Doel, P.

AU - Eifler, T. F.

AU - Everett, S.

AU - Frieman, J.

AU - García-Bellido, J.

AU - Gaztanaga, E.

AU - Gruen, D.

AU - Gruendl, R. A.

AU - Gschwend, J.

AU - Gutierrez, G.

AU - Hinton, S. R.

AU - Hollowood, D. L.

AU - Honscheid, K.

AU - James, D. J.

AU - Kuehn, K.

AU - Maia, M. A.G.

AU - Menanteau, F.

AU - Miquel, R.

AU - Palmese, A.

AU - Paz-Chinchón, F.

AU - Plazas, A. A.

AU - Sanchez, E.

AU - Scarpine, V.

AU - Schubnell, M.

AU - Serrano, S.

AU - Sevilla-Noarbe, I.

AU - Smith, M.

AU - Soares-Santos, M.

AU - Suchyta, E.

AU - Swanson, M. E.C.

AU - Tarle, G.

AU - Walker, A. R.

AU - Wilkinson, R. D.

PY - 2021/8/1

Y1 - 2021/8/1

N2 - 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 g 0 ∼ 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.

AB - 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 g 0 ∼ 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.

UR - http://www.scopus.com/inward/record.url?scp=85112668169&partnerID=8YFLogxK

U2 - 10.3847/1538-4357/ac0443

DO - 10.3847/1538-4357/ac0443

M3 - Article

AN - SCOPUS:85112668169

SN - 0004-637X

VL - 916

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 2

M1 - 81

ER -

A Deeper Look at des Dwarf Galaxy Candidates: Grus i and Indus ii

Abstract

Access to Document

Other files and links

Fingerprint

Cite this