The Pristine Inner Galaxy Survey (PIGS) I: tracing the kinematics of metal-poor stars in the Galactic bulge

A. Arentsen; E. Starkenburg; N. F. Martin; V. Hill; R. Ibata; A. Kunder; M. Schultheis; K. A. Venn; D. B. Zucker; D. Aguado; R. Carlberg; J. I. González Hernández; C. Lardo; N. Longeard; K. Malhan; J. F. Navarro; R. Sánchez-Janssen; F. Sestito; G. Thomas; K. Youakim; G. F. Lewis; J. D. Simpson; Z. Wan

doi:10.1093/mnrasl/slz156

The Pristine Inner Galaxy Survey (PIGS) I: tracing the kinematics of metal-poor stars in the Galactic bulge

A. Arentsen^*, E. Starkenburg, N. F. Martin, V. Hill, R. Ibata, A. Kunder, M. Schultheis, K. A. Venn, D. B. Zucker, D. Aguado, R. Carlberg, J. I. González Hernández, C. Lardo, N. Longeard, K. Malhan, J. F. Navarro, R. Sánchez-Janssen, F. Sestito, G. Thomas, K. YouakimG. F. Lewis, J. D. Simpson, Z. Wan

^*Corresponding author for this work

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Abstract

Our Galaxy is known to contain a central boxy/peanut-shaped bulge, yet the importance of a classical, pressure-supported component within the central part of the Milky Way is still being debated. It should be most visible at low metallicity, a regime that has not yet been studied in detail. Using metallicity-sensitive narrow-band photometry, the Pristine Inner Galaxy Survey (PIGS) has collected a large sample of metal-poor ([Fe/H]<-1.0) stars in the inner Galaxy to address this open question. We use PIGS to trace the metal-poor inner Galaxy kinematics as function of metallicity for the first time. We find that the rotational signal decreases with decreasing [Fe/H], until it becomes negligible for the most metal-poor stars. Additionally, the velocity dispersion increases with decreasing metallicity for -3.0<[Fe/H]<-0.5, with a gradient of-44 ± 4 km s^-1 dex^-1. These observations may signal a transition between Galactic components of different metallicities and kinematics, a different mapping on to the boxy/peanut-shaped bulge for former disc stars of different metallicities and/or the secular dynamical and gravitational influence of the bar on the pressure-supported component. Our results provide strong constraints on models that attempt to explain the properties of the inner Galaxy.

Original language	English
Pages (from-to)	L11-L16
Number of pages	6
Journal	Monthly Notices of the Royal Astronomical Society: Letters
Volume	491
Issue number	1
DOIs	https://doi.org/10.1093/mnrasl/slz156
Publication status	Published - Jan 2020

Bibliographical note

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society: Letters, Volume 491, Issue 1, January 2020, Pages L11–L16, https://doi.org/10.1093/mnrasl/slz156. Copyright 2019 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

Keywords

Galaxy: bulge
Galaxy: evolution
Galaxy: formation
Galaxy: halo
Galaxy: kinematics and dynamics
Galaxy: structure

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10.1093/mnrasl/slz156

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Arentsen, A., Starkenburg, E., Martin, N. F., Hill, V., Ibata, R., Kunder, A., Schultheis, M., Venn, K. A., Zucker, D. B., Aguado, D., Carlberg, R., González Hernández, J. I., Lardo, C., Longeard, N., Malhan, K., Navarro, J. F., Sánchez-Janssen, R., Sestito, F., Thomas, G., ... Wan, Z. (2020). The Pristine Inner Galaxy Survey (PIGS) I: tracing the kinematics of metal-poor stars in the Galactic bulge. Monthly Notices of the Royal Astronomical Society: Letters, 491(1), L11-L16. https://doi.org/10.1093/mnrasl/slz156

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title = "The Pristine Inner Galaxy Survey (PIGS) I: tracing the kinematics of metal-poor stars in the Galactic bulge",

abstract = "Our Galaxy is known to contain a central boxy/peanut-shaped bulge, yet the importance of a classical, pressure-supported component within the central part of the Milky Way is still being debated. It should be most visible at low metallicity, a regime that has not yet been studied in detail. Using metallicity-sensitive narrow-band photometry, the Pristine Inner Galaxy Survey (PIGS) has collected a large sample of metal-poor ([Fe/H]<-1.0) stars in the inner Galaxy to address this open question. We use PIGS to trace the metal-poor inner Galaxy kinematics as function of metallicity for the first time. We find that the rotational signal decreases with decreasing [Fe/H], until it becomes negligible for the most metal-poor stars. Additionally, the velocity dispersion increases with decreasing metallicity for -3.0<[Fe/H]<-0.5, with a gradient of-44 ± 4 km s-1 dex-1. These observations may signal a transition between Galactic components of different metallicities and kinematics, a different mapping on to the boxy/peanut-shaped bulge for former disc stars of different metallicities and/or the secular dynamical and gravitational influence of the bar on the pressure-supported component. Our results provide strong constraints on models that attempt to explain the properties of the inner Galaxy.",

keywords = "Galaxy: bulge, Galaxy: evolution, Galaxy: formation, Galaxy: halo, Galaxy: kinematics and dynamics, Galaxy: structure",

author = "A. Arentsen and E. Starkenburg and Martin, {N. F.} and V. Hill and R. Ibata and A. Kunder and M. Schultheis and Venn, {K. A.} and Zucker, {D. B.} and D. Aguado and R. Carlberg and {Gonz{\'a}lez Hern{\'a}ndez}, {J. I.} and C. Lardo and N. Longeard and K. Malhan and Navarro, {J. F.} and R. S{\'a}nchez-Janssen and F. Sestito and G. Thomas and K. Youakim and Lewis, {G. F.} and Simpson, {J. D.} and Z. Wan",

note = "This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society: Letters, Volume 491, Issue 1, January 2020, Pages L11–L16, https://doi.org/10.1093/mnrasl/slz156. Copyright 2019 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.",

year = "2020",

month = jan,

doi = "10.1093/mnrasl/slz156",

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Arentsen, A, Starkenburg, E, Martin, NF, Hill, V, Ibata, R, Kunder, A, Schultheis, M, Venn, KA, Zucker, DB, Aguado, D, Carlberg, R, González Hernández, JI, Lardo, C, Longeard, N, Malhan, K, Navarro, JF, Sánchez-Janssen, R, Sestito, F, Thomas, G, Youakim, K, Lewis, GF, Simpson, JD & Wan, Z 2020, 'The Pristine Inner Galaxy Survey (PIGS) I: tracing the kinematics of metal-poor stars in the Galactic bulge', Monthly Notices of the Royal Astronomical Society: Letters, vol. 491, no. 1, pp. L11-L16. https://doi.org/10.1093/mnrasl/slz156

TY - JOUR

T1 - The Pristine Inner Galaxy Survey (PIGS) I

T2 - tracing the kinematics of metal-poor stars in the Galactic bulge

AU - Arentsen, A.

AU - Starkenburg, E.

AU - Martin, N. F.

AU - Hill, V.

AU - Ibata, R.

AU - Kunder, A.

AU - Schultheis, M.

AU - Venn, K. A.

AU - Zucker, D. B.

AU - Aguado, D.

AU - Carlberg, R.

AU - González Hernández, J. I.

AU - Lardo, C.

AU - Longeard, N.

AU - Malhan, K.

AU - Navarro, J. F.

AU - Sánchez-Janssen, R.

AU - Sestito, F.

AU - Thomas, G.

AU - Youakim, K.

AU - Lewis, G. F.

AU - Simpson, J. D.

AU - Wan, Z.

N1 - This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society: Letters, Volume 491, Issue 1, January 2020, Pages L11–L16, https://doi.org/10.1093/mnrasl/slz156. Copyright 2019 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

PY - 2020/1

Y1 - 2020/1

N2 - Our Galaxy is known to contain a central boxy/peanut-shaped bulge, yet the importance of a classical, pressure-supported component within the central part of the Milky Way is still being debated. It should be most visible at low metallicity, a regime that has not yet been studied in detail. Using metallicity-sensitive narrow-band photometry, the Pristine Inner Galaxy Survey (PIGS) has collected a large sample of metal-poor ([Fe/H]<-1.0) stars in the inner Galaxy to address this open question. We use PIGS to trace the metal-poor inner Galaxy kinematics as function of metallicity for the first time. We find that the rotational signal decreases with decreasing [Fe/H], until it becomes negligible for the most metal-poor stars. Additionally, the velocity dispersion increases with decreasing metallicity for -3.0<[Fe/H]<-0.5, with a gradient of-44 ± 4 km s-1 dex-1. These observations may signal a transition between Galactic components of different metallicities and kinematics, a different mapping on to the boxy/peanut-shaped bulge for former disc stars of different metallicities and/or the secular dynamical and gravitational influence of the bar on the pressure-supported component. Our results provide strong constraints on models that attempt to explain the properties of the inner Galaxy.

AB - Our Galaxy is known to contain a central boxy/peanut-shaped bulge, yet the importance of a classical, pressure-supported component within the central part of the Milky Way is still being debated. It should be most visible at low metallicity, a regime that has not yet been studied in detail. Using metallicity-sensitive narrow-band photometry, the Pristine Inner Galaxy Survey (PIGS) has collected a large sample of metal-poor ([Fe/H]<-1.0) stars in the inner Galaxy to address this open question. We use PIGS to trace the metal-poor inner Galaxy kinematics as function of metallicity for the first time. We find that the rotational signal decreases with decreasing [Fe/H], until it becomes negligible for the most metal-poor stars. Additionally, the velocity dispersion increases with decreasing metallicity for -3.0<[Fe/H]<-0.5, with a gradient of-44 ± 4 km s-1 dex-1. These observations may signal a transition between Galactic components of different metallicities and kinematics, a different mapping on to the boxy/peanut-shaped bulge for former disc stars of different metallicities and/or the secular dynamical and gravitational influence of the bar on the pressure-supported component. Our results provide strong constraints on models that attempt to explain the properties of the inner Galaxy.

KW - Galaxy: bulge

KW - Galaxy: evolution

KW - Galaxy: formation

KW - Galaxy: halo

KW - Galaxy: kinematics and dynamics

KW - Galaxy: structure

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U2 - 10.1093/mnrasl/slz156

DO - 10.1093/mnrasl/slz156

M3 - Article

AN - SCOPUS:85074916608

VL - 491

SP - L11-L16

JO - Monthly Notices of the Royal Astronomical Society: Letters

JF - Monthly Notices of the Royal Astronomical Society: Letters

SN - 1745-3925

IS - 1

ER -

The Pristine Inner Galaxy Survey (PIGS) I: tracing the kinematics of metal-poor stars in the Galactic bulge

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Keywords

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