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

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posted on 2023-06-09, 01:06 authored by 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, Kathy RomerKathy 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
We use the first-year Dark Energy Survey (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 1 is found at high significance and appears in the DES images as a compact concentration of faint blue point sources. Assuming different spatial profile parameterizations, the best-fitting heliocentric distance and total absolute magnitude in the range of 77.6-87.1 kpc and -3.00 ? MV ? -2.21, respectively. The half-light radius of this object, rh ˜ 10 pc and total luminosity are consistent with it being a low-mass halo cluster. It is also found to have a very elongated shape (e ˜ 0.57). In addition, our deeper probe of DES first-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.

Funding

Astrophysics and Cosmology - Sussex Consolidated Grant; G1291; STFC-SCIENCE AND TECHNOLOGY FACILITIES COUNCIL; ST/L000652/1

History

Publication status

  • Published

File Version

  • Published version

Journal

Monthly Notices of the Royal Astronomical Society

ISSN

0035-8711

Publisher

Oxford University Press

Issue

1

Volume

458

Page range

603-612

Department affiliated with

  • Physics and Astronomy Publications

Full text available

  • Yes

Peer reviewed?

  • Yes

Legacy Posted Date

2016-05-05

First Open Access (FOA) Date

2016-05-05

First Compliant Deposit (FCD) Date

2016-05-05

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