J/MNRAS/490/5647 Correlations in unbound star trajectories (Montanari+, 2019)
Searching for correlations in Gaia DR2 unbound star trajectories.
Montanari F., Barrado D., Garcia-Bellido J.
<Mon. Not. R. Astron. Soc., 490, 5647-5657 (2019)>
=2019MNRAS.490.5647M 2019MNRAS.490.5647M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, high-velocity ; Milky Way ; Galaxies, nearby ;
Clusters, globular ; Radial velocities ; Space velocities ;
Proper motions ; Stars, distances ; Parallaxes, trigonometric ;
Optical
Keywords: Galaxy: kinematics and dynamics - Galaxy: stellar content -
galaxies: kinematics and dynamics - galaxies: statistics -
dark matter
Abstract:
Scattering events with compact objects are expected in the primordial
black hole (PBH) cold dark matter (CDM) scenario, due to close
encounters between stars and PBHs in the dense environments of dwarf
spheroidals. We develop a Bayesian framework to search for
correlations among Milky Way stellar trajectories and those of
globular clusters and dwarf galaxies in the halo and in other nearby
galaxies. We apply the method to a selection of hypervelocity stars
(HVS) and globular clusters from the Gaia DR2 catalogue and known
nearby (mostly dwarf) galaxies with full phase-space and size
measurements. We report positive evidence for trajectory intersection
∼20-40Myr ago of up to two stars, depending on priors, with the
Sagittarius dwarf spheroidal galaxy (dSph) when assuming the distance
estimates of Marchetti, Rossi & Brown (2019MNRAS.490..157M 2019MNRAS.490..157M). We verify
that the result is compatible with their evolutionary status, setting
a lower bound for their stellar age of ∼100Myr. However, such
scattering events are not confirmed when assuming Anders et al.
(2019A&A...628A..94A 2019A&A...628A..94A, Cat. I/349) distance estimates. We discuss
shortcomings related to present data quality and future prospects for
detection of HVS with the full Gaia catalogue and Sagittarius dSph.
Description:
We base our analysis on the selection of 7183262 hypervelocity stars
provided by Marchetti et al. (2019MNRAS.490..157M 2019MNRAS.490..157M). We clean the
sample by selecting heliocentric total velocities in the Galactic rest
frame large enough compared with their uncertainties,
v-σv≳500km/s, to mitigate errors in Galactic absolute
velocity. And we remove potentially spurious radial velocities
(Boubert et al. 2019MNRAS.486.2618B 2019MNRAS.486.2618B).
Finally Marchetti et al. (2019MNRAS.490..157M 2019MNRAS.490..157M) provides for each star
the probability Pub of being unbound from the Milky Way potential.
Our final selection of 1649 stars takes into account this information
and some photometric and astrometric quality cuts (Schonrich,
McMillan & Eyer 2019MNRAS.487.3568S 2019MNRAS.487.3568S).
We select 52 globular clusters (GC) identified in the Gaia DR2
catalogue (Gaia Collaboration et al. 2018A&A...616A..12G 2018A&A...616A..12G, Cat. I/345)
that report both full phase-space and radius, defined as the maximum
radius at which proper-motion members are found.
We select all galaxies for which we can match position and half-light
radius (measured along major axes), given by McConnachie
(2012AJ....144....4M 2012AJ....144....4M, Cat. J/AJ/144/4), with peculiar motions of
identified dwarf Milky Way satellite galaxies in Gaia DR2 (Fritz et
al. 2018A&A...619A.103F 2018A&A...619A.103F). We also include Antlia II and Andromeda.
This gives a total of 35 galaxies.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
gal.dat 160 35 Nearby galaxies
gc.dat 131 52 Globular clusters
hvs.dat 333 1649 Hypervelocity stars
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
Byte-by-byte Description of file: gal.dat
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Bytes Format Units Label Explanations
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1- 18 A18 --- Name Galaxy name
19 A1 --- n_Name [*] Note (1)
20- 27 F8.4 deg RAdeg Right ascension (J2000)
29- 38 F10.6 deg DEdeg Declination (J2000)
40- 44 F5.2 mag DM ? Distance modulus
46- 49 F4.2 mag E_DM ? Upper error on DM
51- 54 F4.2 mag e_DM ? Lower error on DM
56- 61 F6.3 mas/yr pmRA ? Proper motion in right ascension
63- 68 F6.3 mas/yr pmDE ? Proper motion in declination
70- 74 F5.3 mas/yr e_pmRA ? Error on pmRA
76- 80 F5.3 mas/yr e_pmDE ? Error on pmDE
82- 87 F6.3 --- pmRApmDEcor ? Correlation between proper motion in
right ascension and proper motion in
declination
89- 94 F6.1 km/s RV ? Radial velocity
96- 98 F3.1 km/s e_RV ? Error on RV
100-107 F8.4 arcmin Rad Galaxy radius
109-113 F5.2 arcmin e_Rad ? Lower error on Rad
115-119 F5.2 arcmin E_Rad ? Upper error on Rad
121-126 I6 pc Dist ? Distance
128-131 I4 pc e_Dist ? Error on Dist
133-136 F4.1 km/s Vx ? Galactocentric Cartesian velocity in X
direction
138-141 F4.1 km/s e_Vx ? Error on Vx
143-147 F5.1 km/s Vy ? Galactocentric Cartesian velocity in Y
direction
149-150 I2 km/s e_Vy ? Error on Vy
152-155 F4.1 km/s Vz ? Galactocentric Cartesian velocity in Z
direction
157-160 F4.1 km/s e_Vz ? Error on Vz
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Note (1): All systems are identified as dwarf galaxies, excluding Andromeda,
the Large Magellanic Cloud (LMC), Small Magellanic Cloud (SMC) and objects of
ambiguous nature denoted by an asterisk (*).
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Byte-by-byte Description of file: gc.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Name Galaxy cluster name (NGCNNNN)
9- 16 F8.4 deg RAdeg Right ascension (J2000)
18- 25 F8.4 deg DEdeg Declination (J2000)
27- 34 F8.4 mas/yr pmRA Proper motion in right ascension
36- 43 F8.4 mas/yr pmDE Proper motion in declination
45- 50 F6.4 mas/yr e_pmRA Error on pmRA
52- 57 F6.4 mas/yr e_pmDE Error on pmDE
59- 63 F5.2 --- pmRApmDEcor Correlation between proper motion in
right ascension and proper motion in
declination
65- 71 F7.2 km/s RV Radial velocity
73- 76 F4.2 km/s e_RV Error on RV
78- 83 F6.3 kpc X X position in cartesian heliocentric
coordinates
85- 89 F5.3 kpc e_X Lower error on X
91- 95 F5.3 kpc E_X Upper error on X
97-102 F6.3 kpc Y Y position in cartesian heliocentric
coordinates
104-107 F4.2 kpc e_Y Lower error on Y
109-112 F4.2 kpc E_Y Upper error on Y
114-119 F6.3 kpc Z Z position in cartesian heliocentric
coordinates
121-125 F5.3 kpc e_Z Lower error on Z
127-131 F5.3 kpc E_Z Upper error on Z
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Byte-by-byte Description of file: hvs.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- GaiaDR2 Gaia DR2 source identifier
21- 39 F19.15 deg RAdeg Right ascension (ICRS) at Ep=2015.5
41- 59 F19.15 deg DEdeg Declination (ICRS) at Ep=2015.5
61- 79 F19.15 mas plx Parallax
81- 97 F17.15 mas e_plx Error on plx
99-118 F20.15 mas/yr pmRA Proper motion in right ascension
120-136 F17.15 mas/yr e_pmRA Error on pmRA
138-157 F20.15 mas/yr pmDE Proper motion in declination
159-175 F17.15 mas/yr e_pmDE Error on pmDE
177-185 F9.6 --- pmRApmDEcor Correlation between proper motion in
right ascension and proper motion in
declination
187-206 F20.15 km/s RV Radial velocity derived in
Marchetti et al. (2019MNRAS.490..157M 2019MNRAS.490..157M)
208-225 F18.15 km/s e_RV Error on RV
227-247 F21.15 pc DistM Distance derived in Marchetti et al.
(2019MNRAS.490..157M 2019MNRAS.490..157M)
249-268 F20.15 pc e_DistM Lower error on DistM
270-289 F20.15 pc E_DistM Upper error on DistM
291-301 F11.5 pc DistA ? Distance derived in Anders et al.
(2019A&A...628A..94A 2019A&A...628A..94A, Cat. I/349)
303-312 F10.5 pc e_DistA ? Lower error on DistA
314-323 F10.5 pc E_DistA ? Upper error on DistA
325-333 F9.7 --- Pub Probability of being unbound from the
Milky Way potential (based on DistM)
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 03-Feb-2023