J/MNRAS/501/2279 Stars in the Sagittarius stream (Vasiliev+, 2021)
Tango for three: Sagittarius, LMC, and the Milky Way.
Vasiliev E., Belokurov V., Erkal D.
<Mon. Not. R. Astron. Soc., 501, 2279-2304 (2021)>
=2021MNRAS.501.2279V 2021MNRAS.501.2279V (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, giant ; Parallaxes, trigonometric ;
Proper motions ; Stars, distances ; Radial velocities ;
Abundances, [Fe/H] ; Photometry ; Spectroscopy ; Optical ;
Infrared
Keywords: Galaxy: kinematics and dynamics - Galaxy: structure
Abstract:
We assemble a catalogue of candidate Sagittarius stream members with
5D and 6D phase-space information, using astrometric data from Gaia
DR2, distances estimated from RR Lyrae stars, and line-of-sight
velocities from various spectroscopic surveys. We find a clear
misalignment between the stream track and the direction of the
reflex-corrected proper motions in the leading arm of the stream,
which we interpret as a signature of a time-dependent perturbation of
the gravitational potential. A likely cause of this perturbation is
the recent passage of the most massive Milky Way satellite - the Large
Magellanic Cloud (LMC). We develop novel methods for simulating the
Sagittarius stream in the presence of the LMC, using specially
tailored N-body simulations and a flexible parametrization of the
Milky Way halo density profile. We find that while models without the
LMC can fit most stream features rather well, they fail to reproduce
the misalignment and overestimate the distance to the leading arm
apocentre. On the other hand, models with an LMC mass in the range
(1.3±0.3)x1011M☉ rectify these deficiencies. We demonstrate
that the stream can not be modelled adequately in a static Milky Way.
Instead, our Galaxy is required to lurch toward the massive in-falling
Cloud, giving the Sgr stream its peculiar shape and kinematics. By
exploring the parameter space of Milky Way potentials, we determine
the enclosed mass within 100kpc to be (5.6±0.4)x1011M☉, and
the virial mass to be (9.0±1.3)x1011M☉, and find tentative
evidence for a radially-varying shape and orientation of the Galactic
halo.
Description:
To study the kinematics of the Sgr debris, we concentrate on the red
giant branch (RGB) population. These are the brightest stream members
and therefore have the lowest proper motion uncertainty. We start by
cross-matching the Gaia DR2 source catalogue with the 2MASS catalogue
(Skrutskie et al. 2006AJ....131.1163S 2006AJ....131.1163S, Cat. VII/233). Only objects
with Galactic latitude |b|>5°, extinction-corrected
13<G<18,BP-RP>1 and parallax ϖ<0.1mas as reported by Gaia were
included in the cross-match.
We provide the catalogue of ∼55000 high-probability stream members
described in Section 2, which combines the positions and proper
motions from Gaia, distances estimated from Gaia RR Lyrae stars, and
for a small subset of stars (∼4500) - line-of-sight velocities from
various spectroscopic surveys.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 146 55192 Catalogue of stars in the Sagittarius stream
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 8 F8.4 deg RAdeg Right ascension (J2000)
10- 17 F8.4 deg DEdeg Declination (J2000)
19- 24 F6.3 mas plx Gaia DR2 parallax
26- 30 F5.3 mas e_plx Error on plx
32- 37 F6.3 mas/yr pmRA Proper motion in right ascension
39- 43 F5.3 mas/yr e_pmRA Error on pmRA
45- 50 F6.3 mas/yr pmDE Proper motion in declination
52- 56 F5.3 mas/yr e_pmDE Error on pmDE
58- 62 F5.2 mag Gmag Gaia DR2 G-band magnitude
64- 67 F4.2 mag BPmag Gaia DR2 BP-band magnitude
69- 73 F5.2 mag Jmag 2MASS J-band magnitude
75- 79 F5.2 mag Hmag 2MASS H-band magnitude
81- 85 F5.2 mag Kmag 2MASS K-band magnitude
87- 90 F4.2 mag E(B-V) Reddening from Schlegel, Finkbeiner & Davis
(1998ApJ...500..525S 1998ApJ...500..525S)
92- 96 F5.2 kpc Dist Estimate of the distance from nearby RR Lyrae
stars
98- 102 F5.2 kpc e_Dist Error on Dist
104- 110 F7.2 km/s vLOS ? Heliocentric line-of-sight velocity
112- 116 F5.2 km/s e_vLOS ? Error on vLOS
118- 122 F5.2 [-] [Fe/H] ? Fe/H abundance ratio
124- 127 F4.2 [-] e_[Fe/H] ? Error on [Fe/H]
129 I1 --- Ref ? Reference for the spectroscopic data (1)
131- 138 F8.3 deg Lambda Λ coordinate in the Sgr stream frame (2)
140- 146 F7.3 deg Beta Β coordinate in the Sgr stream frame (2)
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Note (1): Reference as follows:
1 = APOGEE
2 = LAMOST
3 = GAIA RVS
4 = SIMBAD (including data from Frinchaboy et al. 2012ApJ...756...74F 2012ApJ...756...74F,
Cat. J/ApJ/756/74)
5 = SDSS
6 = Penarrubia et al. (2011ApJ...727L...2P 2011ApJ...727L...2P)
Note (2): We define the right-handed celestial coordinate system
Λ, Β that differs from the one used in Majewski et al.
(2003ApJ...599.1082M 2003ApJ...599.1082M) by the sign of Λ: It increases towards
the leading arm, and is zero at the centre of the Sgr remnant. Rather
annoyingly, the other coordinate (Β) is not centred on the
remnant: the latter has Β0∼1.5°; we follow this convention
to match previous studies.
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 17-Oct-2023