GD-1 Stellar Stream and Cocoon in the DESI Early Data Release

M. Valluri; P. Fagrelius; S. E. Koposov; T. S. Li; Oleg Y. Gnedin; E. F. Bell; R. G. Carlberg; A. P. Cooper; J. Aguilar; S. Ahlen; C. Allende Prieto; V. Belokurov; L. Beraldo e Silva; Brooks; A. Byström; T. Claybaugh; Dawson; A. Dey; Doel; J. E. Forero-Romero; Enrique Gaztañaga; S. Gontcho A Gontcho; Han; Honscheid; T. Kisner; A. Kremin; A. Lambert; M. Landriau; Guillou Le Guillou; M. E. Levi; la Macorra de la Macorra; Manera; Martini; G. E. Medina; A. Meisner; Miquel; Moustakas; A. D. Myers; J. Najita; Poppett; Prada; Rezaie; Rossi; A. H. Riley; Sanchez; D. Schlegel; Schubnell; D. Sprayberry; Tarlé; Thomas; B. A. Weaver; R. H. Wechsler; R. Zhou; Zou

doi:10.3847/1538-4357/ada690

GD-1 Stellar Stream and Cocoon in the DESI Early Data Release

M. Valluri, P. Fagrelius, S. E. Koposov, T. S. Li, Oleg Y. Gnedin, E. F. Bell, R. G. Carlberg, A. P. Cooper, J. Aguilar, S. Ahlen, C. Allende Prieto, V. Belokurov, L. Beraldo e Silva, Brooks, A. Byström, T. Claybaugh, Dawson, A. Dey, Doel, J. E. Forero-RomeroGaztañaga, S. Gontcho A Gontcho, Han, Honscheid, T. Kisner, A. Kremin, A. Lambert, M. Landriau, Guillou Le Guillou, M. E. Levi, la Macorra de la Macorra, Manera, Martini, G. E. Medina, A. Meisner, Miquel, Moustakas, A. D. Myers, J. Najita, Poppett, Prada, Rezaie, Rossi, A. H. Riley, Sanchez, D. Schlegel, Schubnell, D. Sprayberry, Tarlé, Thomas, B. A. Weaver, R. H. Wechsler, R. Zhou, Zou

Institute of Cosmology & Gravitation

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

2 Downloads (Pure)

Abstract

We present ∼115 new spectroscopically identified members of the GD-1 tidal stream observed with the 5000-fiber Dark Energy Spectroscopic Instrument (DESI). We confirm the existence of a “cocoon,” which is a broad (FWHM ∼ 2 . ° 932 ∼ 460 pc) and kinematically hot (velocity dispersion, σ ∼ 5-8 km s⁻¹) component that surrounds a narrower (FWHM ∼ 0 . ° 353 ∼ 55 pc) and colder [(σ = 3.09 ± 0.76 km s⁻¹)] thin stream component (based on a median per star velocity precision of 2.7 km s⁻¹). The cocoon extends over at least a 30^∘ segment of the stream observed by DESI. The thin and cocoon components have similar mean values of [Fe/H]: −2.54 ± 0.04 dex and −2.47 ± 0.06 dex, suggestive of a common origin. The data are consistent with the following scenarios for the origin of the cocoon. The progenitor of the GD-1 stream was an accreted globular cluster (GC) and: (a) the cocoon was produced by pre-accretion tidal stripping of the GC while it was still inside its parent dwarf galaxy; (b) the cocoon comprises debris from the parent dwarf galaxy; (c) an initially thin GC tidal stream was heated by impacts from dark subhalos in the Milky Way; (d) an initially thin GC stream was heated by a massive Sagittarius dwarf galaxy; or a combination of some of these. Future DESI spectroscopy and detailed modeling may enable us to distinguish between these possible origins.

Original language	English
Article number	71
Number of pages	19
Journal	Astrophysical Journal
Volume	980
Issue number	1
DOIs	https://doi.org/10.3847/1538-4357/ada690
Publication status	Published - 5 Feb 2025

Keywords

UKRI
STFC
ST/Y001001/1

Access to Document

10.3847/1538-4357/ada690

GD-1 Stellar Stream and Cocoon in the DESI Early Data ReleaseFinal published version, 2.95 MBLicence: CC BY

Cite this

Valluri, M., Fagrelius, P., Koposov, S. E., Li, T. S., Gnedin, O. Y., Bell, E. F., Carlberg, R. G., Cooper, A. P., Aguilar, J., Ahlen, S., Allende Prieto, C., Belokurov, V., Beraldo e Silva, L., Brooks, Byström, A., Claybaugh, T., Dawson, Dey, A., Doel, ... Zou (2025). GD-1 Stellar Stream and Cocoon in the DESI Early Data Release. Astrophysical Journal, 980(1), Article 71. https://doi.org/10.3847/1538-4357/ada690

@article{09c74d71192d4ba98140b7e866260cea,

title = "GD-1 Stellar Stream and Cocoon in the DESI Early Data Release",

abstract = "We present ∼115 new spectroscopically identified members of the GD-1 tidal stream observed with the 5000-fiber Dark Energy Spectroscopic Instrument (DESI). We confirm the existence of a “cocoon,” which is a broad (FWHM ∼ 2 . ° 932 ∼ 460 pc) and kinematically hot (velocity dispersion, σ ∼ 5-8 km s−1) component that surrounds a narrower (FWHM ∼ 0 . ° 353 ∼ 55 pc) and colder [(σ = 3.09 ± 0.76 km s−1)] thin stream component (based on a median per star velocity precision of 2.7 km s−1). The cocoon extends over at least a 30∘ segment of the stream observed by DESI. The thin and cocoon components have similar mean values of [Fe/H]: −2.54 ± 0.04 dex and −2.47 ± 0.06 dex, suggestive of a common origin. The data are consistent with the following scenarios for the origin of the cocoon. The progenitor of the GD-1 stream was an accreted globular cluster (GC) and: (a) the cocoon was produced by pre-accretion tidal stripping of the GC while it was still inside its parent dwarf galaxy; (b) the cocoon comprises debris from the parent dwarf galaxy; (c) an initially thin GC tidal stream was heated by impacts from dark subhalos in the Milky Way; (d) an initially thin GC stream was heated by a massive Sagittarius dwarf galaxy; or a combination of some of these. Future DESI spectroscopy and detailed modeling may enable us to distinguish between these possible origins.",

keywords = "UKRI, STFC, ST/Y001001/1",

author = "M. Valluri and P. Fagrelius and Koposov, {S. E.} and Li, {T. S.} and Gnedin, {Oleg Y.} and Bell, {E. F.} and Carlberg, {R. G.} and Cooper, {A. P.} and J. Aguilar and S. Ahlen and {Allende Prieto}, C. and V. Belokurov and {Beraldo e Silva}, L. and Brooks and A. Bystr{\"o}m and T. Claybaugh and Dawson and A. Dey and Doel and Forero-Romero, {J. E.} and Gazta{\~n}aga and {Gontcho A Gontcho}, S. and Han and Honscheid and T. Kisner and A. Kremin and A. Lambert and M. Landriau and {Le Guillou}, Guillou and Levi, {M. E.} and {de la Macorra}, {la Macorra} and Manera and Martini and Medina, {G. E.} and A. Meisner and Miquel and Moustakas and Myers, {A. D.} and J. Najita and Poppett and Prada and Rezaie and Rossi and Riley, {A. H.} and Sanchez and D. Schlegel and Schubnell and D. Sprayberry and Tarl{\'e} and Thomas and Weaver, {B. A.} and Wechsler, {R. H.} and R. Zhou and Zou",

note = "Publisher Copyright: {\textcopyright} 2025. The Author(s). Published by the American Astronomical Society.",

year = "2025",

month = feb,

day = "5",

doi = "10.3847/1538-4357/ada690",

language = "English",

volume = "980",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "American Astronomical Society",

number = "1",

}

Valluri, M, Fagrelius, P, Koposov, SE, Li, TS, Gnedin, OY, Bell, EF, Carlberg, RG, Cooper, AP, Aguilar, J, Ahlen, S, Allende Prieto, C, Belokurov, V, Beraldo e Silva, L, Brooks, Byström, A, Claybaugh, T, Dawson, Dey, A, Doel, Forero-Romero, JE, Gaztañaga, Gontcho A Gontcho, S, Han, Honscheid, Kisner, T, Kremin, A, Lambert, A, Landriau, M, Le Guillou, G, Levi, ME, de la Macorra, LM, Manera, Martini, Medina, GE, Meisner, A, Miquel, Moustakas, Myers, AD, Najita, J, Poppett, Prada, Rezaie, Rossi, Riley, AH, Sanchez, Schlegel, D, Schubnell, Sprayberry, D, Tarlé, Thomas, Weaver, BA, Wechsler, RH, Zhou, R & Zou 2025, 'GD-1 Stellar Stream and Cocoon in the DESI Early Data Release', Astrophysical Journal, vol. 980, no. 1, 71. https://doi.org/10.3847/1538-4357/ada690

TY - JOUR

T1 - GD-1 Stellar Stream and Cocoon in the DESI Early Data Release

AU - Valluri, M.

AU - Fagrelius, P.

AU - Koposov, S. E.

AU - Li, T. S.

AU - Gnedin, Oleg Y.

AU - Bell, E. F.

AU - Carlberg, R. G.

AU - Cooper, A. P.

AU - Aguilar, J.

AU - Ahlen, S.

AU - Allende Prieto, C.

AU - Belokurov, V.

AU - Beraldo e Silva, L.

AU - Brooks,

AU - Byström, A.

AU - Claybaugh, T.

AU - Dawson,

AU - Dey, A.

AU - Doel,

AU - Forero-Romero, J. E.

AU - Gaztañaga, null

AU - Gontcho A Gontcho, S.

AU - Han,

AU - Honscheid,

AU - Kisner, T.

AU - Kremin, A.

AU - Lambert, A.

AU - Landriau, M.

AU - Le Guillou, Guillou

AU - Levi, M. E.

AU - de la Macorra, la Macorra

AU - Manera,

AU - Martini,

AU - Medina, G. E.

AU - Meisner, A.

AU - Miquel,

AU - Moustakas,

AU - Myers, A. D.

AU - Najita, J.

AU - Poppett,

AU - Prada,

AU - Rezaie,

AU - Rossi,

AU - Riley, A. H.

AU - Sanchez,

AU - Schlegel, D.

AU - Schubnell,

AU - Sprayberry, D.

AU - Tarlé,

AU - Thomas,

AU - Weaver, B. A.

AU - Wechsler, R. H.

AU - Zhou, R.

AU - Zou,

PY - 2025/2/5

Y1 - 2025/2/5

N2 - We present ∼115 new spectroscopically identified members of the GD-1 tidal stream observed with the 5000-fiber Dark Energy Spectroscopic Instrument (DESI). We confirm the existence of a “cocoon,” which is a broad (FWHM ∼ 2 . ° 932 ∼ 460 pc) and kinematically hot (velocity dispersion, σ ∼ 5-8 km s−1) component that surrounds a narrower (FWHM ∼ 0 . ° 353 ∼ 55 pc) and colder [(σ = 3.09 ± 0.76 km s−1)] thin stream component (based on a median per star velocity precision of 2.7 km s−1). The cocoon extends over at least a 30∘ segment of the stream observed by DESI. The thin and cocoon components have similar mean values of [Fe/H]: −2.54 ± 0.04 dex and −2.47 ± 0.06 dex, suggestive of a common origin. The data are consistent with the following scenarios for the origin of the cocoon. The progenitor of the GD-1 stream was an accreted globular cluster (GC) and: (a) the cocoon was produced by pre-accretion tidal stripping of the GC while it was still inside its parent dwarf galaxy; (b) the cocoon comprises debris from the parent dwarf galaxy; (c) an initially thin GC tidal stream was heated by impacts from dark subhalos in the Milky Way; (d) an initially thin GC stream was heated by a massive Sagittarius dwarf galaxy; or a combination of some of these. Future DESI spectroscopy and detailed modeling may enable us to distinguish between these possible origins.

AB - We present ∼115 new spectroscopically identified members of the GD-1 tidal stream observed with the 5000-fiber Dark Energy Spectroscopic Instrument (DESI). We confirm the existence of a “cocoon,” which is a broad (FWHM ∼ 2 . ° 932 ∼ 460 pc) and kinematically hot (velocity dispersion, σ ∼ 5-8 km s−1) component that surrounds a narrower (FWHM ∼ 0 . ° 353 ∼ 55 pc) and colder [(σ = 3.09 ± 0.76 km s−1)] thin stream component (based on a median per star velocity precision of 2.7 km s−1). The cocoon extends over at least a 30∘ segment of the stream observed by DESI. The thin and cocoon components have similar mean values of [Fe/H]: −2.54 ± 0.04 dex and −2.47 ± 0.06 dex, suggestive of a common origin. The data are consistent with the following scenarios for the origin of the cocoon. The progenitor of the GD-1 stream was an accreted globular cluster (GC) and: (a) the cocoon was produced by pre-accretion tidal stripping of the GC while it was still inside its parent dwarf galaxy; (b) the cocoon comprises debris from the parent dwarf galaxy; (c) an initially thin GC tidal stream was heated by impacts from dark subhalos in the Milky Way; (d) an initially thin GC stream was heated by a massive Sagittarius dwarf galaxy; or a combination of some of these. Future DESI spectroscopy and detailed modeling may enable us to distinguish between these possible origins.

KW - UKRI

KW - STFC

KW - ST/Y001001/1

UR - http://www.scopus.com/inward/record.url?scp=85219677531&partnerID=8YFLogxK

U2 - 10.3847/1538-4357/ada690

DO - 10.3847/1538-4357/ada690

M3 - Article

AN - SCOPUS:85219677531

SN - 0004-637X

VL - 980

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1

M1 - 71

ER -

GD-1 Stellar Stream and Cocoon in the DESI Early Data Release

Abstract

Keywords

Access to Document

Fingerprint

Cite this