Digging deeper into the southern skies: a compact Milky-Way companion discovered in first-year Dark Energy Survey data

E. Luque; A. Queiroz; B. Santiago; A. Pieres; E. Balbinot; K. Bechtol; A. Drlica-Wagner; A. Fausti Neto; L. N. da Costa; M. A. G. Maia; B. Yanny; T. Abbott; S. Allam; A. Benoit-Lévy; E. Bertin; D. Brooks; E. Buckley-Geer; D. L. Burke; A. Carnero Rosell; M. Carrasco Kind; J. Carretero; C. E. Cunha; S. Desai; H. T. Diehl; J. P. Dietrich; T. F. Eifler; D. A. Finley; B. Flaugher; P. Fosalba; J. Frieman; D. W. Gerdes; D. Gruen; G. Gutierrez; K. Honscheid; D. J. James; K. Kuehn; N. Kuropatkin; O. Lahav; T. S. Li; M. March; J. L. Marshall; P. Martini; R. Miquel; E. Neilsen; R. C. Nichol; B. Nord; R. Ogando; A. A. Plazas; A. K. Romer; A. Roodman; E. Sanchez; V. Scarpine; M. Schubnell; I. Sevilla-Noarbe; R. C. Smith; M. Soares-Santos; F. Sobreira; E. Suchyta; M. E. C. Swanson; G. Tarle; J. Thaler; D. Tucker; A. R. Walker; Y. Zhang

doi:10.1093/mnras/stw302

Digging deeper into the southern skies: a compact Milky-Way companion discovered in first-year Dark Energy Survey data

E. Luque, A. Queiroz, B. Santiago, A. Pieres, E. Balbinot, K. Bechtol, A. Drlica-Wagner, A. Fausti Neto, L. N. da Costa, M. A. G. Maia, B. Yanny, T. Abbott, S. Allam, A. Benoit-Lévy, E. Bertin, D. Brooks, E. Buckley-Geer, D. L. Burke, A. Carnero Rosell, M. Carrasco KindJ. Carretero, C. E. Cunha, S. Desai, H. T. Diehl, J. P. Dietrich, T. F. Eifler, D. A. Finley, B. Flaugher, P. Fosalba, J. Frieman, D. W. Gerdes, D. Gruen, G. Gutierrez, K. Honscheid, D. J. James, K. Kuehn, N. Kuropatkin, O. Lahav, T. S. Li, M. March, J. L. Marshall, P. Martini, R. Miquel, E. Neilsen, R. C. Nichol, B. Nord, R. Ogando, A. A. Plazas, A. K. Romer, A. Roodman, E. Sanchez, V. Scarpine, M. Schubnell, I. Sevilla-Noarbe, R. C. Smith, M. Soares-Santos, F. Sobreira, E. Suchyta, M. E. C. Swanson, G. Tarle, J. Thaler, D. Tucker, A. R. Walker, Y. Zhang

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Abstract

The Dark Energy Survey (DES) is a 5000 sq. degree survey in the southern hemisphere, which is rapidly reducing the existing north-south asymmetry in the census of MW satellites and other stellar substructure. We use the first-year DES data down to previously unprobed photometric depths to search for stellar systems in the Galactic halo, therefore complementing the previous analysis of the same data carried out by our group earlier this year. Our search is based on a matched filter algorithm that produces stellar density maps consistent with stellar population models of various ages, metallicities, and distances over the survey area. The most conspicuous density peaks in these maps have been identified automatically and ranked according to their significance and recurrence for different input models. We report the discovery of one additional stellar system besides those previously found by several authors using the same first-year DES data. The object is compact, and consistent with being dominated by an old and metal-poor population. DES J0034-4902 is found at high significance and appears in the DES images as a compact concentration of faint blue point sources at ~ 87 {kpc}. Its half-light radius of r_h = 9.88 +/- 4.31 {pc} and total luminosity of M_V ~ -3.05_{-0.42}^{+0.69} are consistent with it being a low mass halo cluster. It is also found to have a very elongated shape. In addition, our deeper probe of DES 1st year data confirms the recently reported satellite galaxy candidate Horologium II as a significant stellar overdensity. We also infer its structural properties and compare them to those reported in the literature.

Original language	English
Pages (from-to)	603-612
Number of pages	10
Journal	Monthly Notices of the Royal Astronomical Society
Volume	458
Issue number	1
Early online date	9 Feb 2016
DOIs	https://doi.org/10.1093/mnras/stw302
Publication status	Published - May 2016

Keywords

astro-ph.GA
astro-ph.SR
globular clusters: general
globular clusters: individual (DES 1)
galaxies: dwarf
RCUK
STFC

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10.1093/mnras/stw302

Digging deeper into the Southern skies
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
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Luque, E., Queiroz, A., Santiago, B., Pieres, A., Balbinot, E., Bechtol, K., Drlica-Wagner, A., Neto, A. F., Costa, L. N. D., Maia, M. A. G., Yanny, B., Abbott, T., Allam, S., Benoit-Lévy, A., Bertin, E., Brooks, D., Buckley-Geer, E., Burke, D. L., Rosell, A. C., ... Zhang, Y. (2016). Digging deeper into the southern skies: a compact Milky-Way companion discovered in first-year Dark Energy Survey data. Monthly Notices of the Royal Astronomical Society, 458(1), 603-612. https://doi.org/10.1093/mnras/stw302

@article{5b0d86f9e29341c9b04332ed0830e95a,

title = "Digging deeper into the southern skies: a compact Milky-Way companion discovered in first-year Dark Energy Survey data",

abstract = "The Dark Energy Survey (DES) is a 5000 sq. degree survey in the southern hemisphere, which is rapidly reducing the existing north-south asymmetry in the census of MW satellites and other stellar substructure. We use the first-year DES data down to previously unprobed photometric depths to search for stellar systems in the Galactic halo, therefore complementing the previous analysis of the same data carried out by our group earlier this year. Our search is based on a matched filter algorithm that produces stellar density maps consistent with stellar population models of various ages, metallicities, and distances over the survey area. The most conspicuous density peaks in these maps have been identified automatically and ranked according to their significance and recurrence for different input models. We report the discovery of one additional stellar system besides those previously found by several authors using the same first-year DES data. The object is compact, and consistent with being dominated by an old and metal-poor population. DES J0034-4902 is found at high significance and appears in the DES images as a compact concentration of faint blue point sources at ~ 87 {kpc}. Its half-light radius of r_h = 9.88 +/- 4.31 {pc} and total luminosity of M_V ~ -3.05_{-0.42}^{+0.69} are consistent with it being a low mass halo cluster. It is also found to have a very elongated shape. In addition, our deeper probe of DES 1st year data confirms the recently reported satellite galaxy candidate Horologium II as a significant stellar overdensity. We also infer its structural properties and compare them to those reported in the literature.",

keywords = "astro-ph.GA, astro-ph.SR, globular clusters: general, globular clusters: individual (DES 1), galaxies: dwarf, RCUK, STFC",

author = "E. Luque and A. Queiroz and B. Santiago and A. Pieres and E. Balbinot and K. Bechtol and A. Drlica-Wagner and Neto, {A. Fausti} and Costa, {L. N. da} and Maia, {M. A. G.} and B. Yanny and T. Abbott and S. Allam and A. Benoit-L{\'e}vy and E. Bertin and D. Brooks and E. Buckley-Geer and Burke, {D. L.} and Rosell, {A. Carnero} and Kind, {M. Carrasco} and J. Carretero and Cunha, {C. E.} and S. Desai and Diehl, {H. T.} and Dietrich, {J. P.} and Eifler, {T. F.} and Finley, {D. A.} and B. Flaugher and P. Fosalba and J. Frieman and Gerdes, {D. W.} and D. Gruen and G. Gutierrez and K. Honscheid and James, {D. J.} and K. Kuehn and N. Kuropatkin and O. Lahav and Li, {T. S.} and M. March and Marshall, {J. L.} and P. Martini and R. Miquel and E. Neilsen and Nichol, {R. C.} and B. Nord and R. Ogando and Plazas, {A. A.} and Romer, {A. K.} and A. Roodman and E. Sanchez and V. Scarpine and M. Schubnell and I. Sevilla-Noarbe and Smith, {R. C.} and M. Soares-Santos and F. Sobreira and E. Suchyta and Swanson, {M. E. C.} and G. Tarle and J. Thaler and D. Tucker and Walker, {A. R.} and Y. Zhang",

year = "2016",

month = may,

doi = "10.1093/mnras/stw302",

language = "English",

volume = "458",

pages = "603--612",

journal = "Monthly Notices of the Royal Astronomical Society",

issn = "0035-8711",

publisher = "Oxford University Press",

number = "1",

}

Luque, E, Queiroz, A, Santiago, B, Pieres, A, Balbinot, E, Bechtol, K, Drlica-Wagner, A, Neto, AF, Costa, LND, Maia, MAG, Yanny, B, Abbott, T, Allam, S, Benoit-Lévy, A, Bertin, E, Brooks, D, Buckley-Geer, E, Burke, DL, Rosell, AC, Kind, MC, Carretero, J, Cunha, CE, Desai, S, Diehl, HT, Dietrich, JP, Eifler, TF, Finley, DA, Flaugher, B, Fosalba, P, Frieman, J, Gerdes, DW, Gruen, D, Gutierrez, G, Honscheid, K, James, DJ, Kuehn, K, Kuropatkin, N, Lahav, O, Li, TS, March, M, Marshall, JL, Martini, P, Miquel, R, Neilsen, E, Nichol, RC, Nord, B, Ogando, R, Plazas, AA, Romer, AK, Roodman, A, Sanchez, E, Scarpine, V, Schubnell, M, Sevilla-Noarbe, I, Smith, RC, Soares-Santos, M, Sobreira, F, Suchyta, E, Swanson, MEC, Tarle, G, Thaler, J, Tucker, D, Walker, AR & Zhang, Y 2016, 'Digging deeper into the southern skies: a compact Milky-Way companion discovered in first-year Dark Energy Survey data', Monthly Notices of the Royal Astronomical Society, vol. 458, no. 1, pp. 603-612. https://doi.org/10.1093/mnras/stw302

TY - JOUR

T1 - Digging deeper into the southern skies

T2 - a compact Milky-Way companion discovered in first-year Dark Energy Survey data

AU - Luque, E.

AU - Queiroz, A.

AU - Santiago, B.

AU - Pieres, A.

AU - Balbinot, E.

AU - Bechtol, K.

AU - Drlica-Wagner, A.

AU - Neto, A. Fausti

AU - Costa, L. N. da

AU - Maia, M. A. G.

AU - Yanny, B.

AU - Abbott, T.

AU - Allam, S.

AU - Benoit-Lévy, A.

AU - Bertin, E.

AU - Brooks, D.

AU - Buckley-Geer, E.

AU - Burke, D. L.

AU - Rosell, A. Carnero

AU - Kind, M. Carrasco

AU - Carretero, J.

AU - Cunha, C. E.

AU - Desai, S.

AU - Diehl, H. T.

AU - Dietrich, J. P.

AU - Eifler, T. F.

AU - Finley, D. A.

AU - Flaugher, B.

AU - Fosalba, P.

AU - Frieman, J.

AU - Gerdes, D. W.

AU - Gruen, D.

AU - Gutierrez, G.

AU - Honscheid, K.

AU - James, D. J.

AU - Kuehn, K.

AU - Kuropatkin, N.

AU - Lahav, O.

AU - Li, T. S.

AU - March, M.

AU - Marshall, J. L.

AU - Martini, P.

AU - Miquel, R.

AU - Neilsen, E.

AU - Nichol, R. C.

AU - Nord, B.

AU - Ogando, R.

AU - Plazas, A. A.

AU - Romer, A. K.

AU - Roodman, A.

AU - Sanchez, E.

AU - Scarpine, V.

AU - Schubnell, M.

AU - Sevilla-Noarbe, I.

AU - Smith, R. C.

AU - Soares-Santos, M.

AU - Sobreira, F.

AU - Suchyta, E.

AU - Swanson, M. E. C.

AU - Tarle, G.

AU - Thaler, J.

AU - Tucker, D.

AU - Walker, A. R.

AU - Zhang, Y.

PY - 2016/5

Y1 - 2016/5

N2 - The Dark Energy Survey (DES) is a 5000 sq. degree survey in the southern hemisphere, which is rapidly reducing the existing north-south asymmetry in the census of MW satellites and other stellar substructure. We use the first-year DES data down to previously unprobed photometric depths to search for stellar systems in the Galactic halo, therefore complementing the previous analysis of the same data carried out by our group earlier this year. Our search is based on a matched filter algorithm that produces stellar density maps consistent with stellar population models of various ages, metallicities, and distances over the survey area. The most conspicuous density peaks in these maps have been identified automatically and ranked according to their significance and recurrence for different input models. We report the discovery of one additional stellar system besides those previously found by several authors using the same first-year DES data. The object is compact, and consistent with being dominated by an old and metal-poor population. DES J0034-4902 is found at high significance and appears in the DES images as a compact concentration of faint blue point sources at ~ 87 {kpc}. Its half-light radius of r_h = 9.88 +/- 4.31 {pc} and total luminosity of M_V ~ -3.05_{-0.42}^{+0.69} are consistent with it being a low mass halo cluster. It is also found to have a very elongated shape. In addition, our deeper probe of DES 1st year data confirms the recently reported satellite galaxy candidate Horologium II as a significant stellar overdensity. We also infer its structural properties and compare them to those reported in the literature.

AB - The Dark Energy Survey (DES) is a 5000 sq. degree survey in the southern hemisphere, which is rapidly reducing the existing north-south asymmetry in the census of MW satellites and other stellar substructure. We use the first-year DES data down to previously unprobed photometric depths to search for stellar systems in the Galactic halo, therefore complementing the previous analysis of the same data carried out by our group earlier this year. Our search is based on a matched filter algorithm that produces stellar density maps consistent with stellar population models of various ages, metallicities, and distances over the survey area. The most conspicuous density peaks in these maps have been identified automatically and ranked according to their significance and recurrence for different input models. We report the discovery of one additional stellar system besides those previously found by several authors using the same first-year DES data. The object is compact, and consistent with being dominated by an old and metal-poor population. DES J0034-4902 is found at high significance and appears in the DES images as a compact concentration of faint blue point sources at ~ 87 {kpc}. Its half-light radius of r_h = 9.88 +/- 4.31 {pc} and total luminosity of M_V ~ -3.05_{-0.42}^{+0.69} are consistent with it being a low mass halo cluster. It is also found to have a very elongated shape. In addition, our deeper probe of DES 1st year data confirms the recently reported satellite galaxy candidate Horologium II as a significant stellar overdensity. We also infer its structural properties and compare them to those reported in the literature.

KW - astro-ph.GA

KW - astro-ph.SR

KW - globular clusters: general

KW - globular clusters: individual (DES 1)

KW - galaxies: dwarf

KW - RCUK

KW - STFC

U2 - 10.1093/mnras/stw302

DO - 10.1093/mnras/stw302

M3 - Article

SN - 0035-8711

VL - 458

SP - 603

EP - 612

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 1

ER -

Digging deeper into the southern skies: a compact Milky-Way companion discovered in first-year Dark Energy Survey data

Abstract

Keywords

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