Title: The Phoenix stream: A cold stream in the southern hemisphere

Abstract

In this study, we report the discovery of a stellar stream in the Dark Energy Survey (DES) Year 1 (Y1A1) data. The discovery was made through simple color-magnitude filters and visual inspection of the Y1A1 data. We refer to this new object as the Phoenix stream, after its resident constellation. After subtraction of the background stellar population we detect a clear signal of a simple stellar population. By fitting the ridge line of the stream in color-magnitude space, we find that a stellar population with age $$\tau=11.5\pm0.5$$ Gyr and $[Fe/H]<-1.6$ located 17.5$$\pm$$0.9 kpc from the Sun gives an adequate description of the stream stellar population. The stream is detected over an extension of 8$$^{\circ}.$$1 (2.5 kpc) and has a width of $$\sim$$54 pc assuming a Gaussian profile, indicating that a globular cluster is a probable progenitor. There is no known globular cluster within 5 kpc compatible with being the progenitor of the stream, assuming that the stream traces its orbit. We examined overdensities along the stream, however no obvious counterpart bound stellar system is visible in the coadded images. We also find overdensities along the stream that appear to be symmetrically distributed - consistent with the epicyclic overdensity scenario for the formation of cold streams - as well as a misalignment between the Northern and Southern part of stream. Despite the close proximity we find no evidence that this stream and the halo cluster NGC 1261 have a common accretion origin linked to the recently found EriPhe overdensity (Li et al. 2016).

Authors:

Balbinot, E. ^[1]

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+ Show Author Affiliations

1. Univ. of Surrey, Guildford (United Kingdom). et al.

Publication Date:

Thu Mar 17 00:00:00 EDT 2016

Research Org.:

SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)

Sponsoring Org.:

USDOE Office of Science (SC), High Energy Physics (HEP)

Contributing Org.:

DES Collaboration

OSTI Identifier:

1247527

Alternate Identifier(s):

OSTI ID: 1259213

Report Number(s):

arXiv:1509.04283; FERMILAB-PUB-16-041-AE; SLAC-PUB-16590
Journal ID: ISSN 1538-4357; 1423504

Grant/Contract Number:  

AC02-07CH11359; AC02-76SF00515

Resource Type:

Accepted Manuscript

Journal Name:

The Astrophysical Journal (Online)

Additional Journal Information:

Journal Name: The Astrophysical Journal (Online); Journal Volume: 820; Journal Issue: 1; Journal ID: ISSN 1538-4357

Publisher:

Institute of Physics (IOP)

Country of Publication:

United States

Language:

English

Subject:

79 ASTRONOMY AND ASTROPHYSICS