A disk origin for inner stellar halo structures around the Milky Way Adrian Price-Whelan (Princeton University)! adrn " adrianprw Kathryn Johnston, Allyson Sheffield, Chervin Laporte, Maria Bergemann, Branimir Sesar, Ting Li, Chris Hayes, Steve Majewski, Rachael Beaton, Judy Cohen, Andy Tzanidakis
Streams vs. structures Grillmair & Carlin 2016
Streams vs. structures C. Slater
Streams vs. structures Eastern Banded Structure (EBS) Monoceros, Anticenter Stream (ACS) Triangulum-Andromeda (TriAnd) C. Slater
Structures / clouds / shells Anticenter Stream (ACS) Eastern Banded Structure (EBS) Monoceros / Giant Anticenter Stellar Stream (GASS) / Low Latitude Stream (LLS) Triangulum-Andromeda A13 Hercules-Aquila cloud Virgo over-density Eridanus-Phoenix d ~ 8 kpc d ~ 10 kpc d ~ 8 12 kpc d ~ 15 30 kpc d ~ 12 15 kpc d ~ 10 20 kpc d ~ 6 20 kpc d ~ 16 kpc (heliocentric)
Accreted debris? Kicked out of disk? D. Hendel A. Tzanidakis & C. Laporte
Accreted debris? Kicked out of disk? D. Hendel A. Tzanidakis & C. Laporte
the Triangulum-Andromeda region
the Triangulum-Andromeda region
Annoying Milky Way Foreground 20 i 22 24 0 1 2 g i Martin+2007
Annoying Milky Way Foreground Monoceros 20 i d 20 30 kpc 22 24 Triand 1 & 2 0 1 2 g i Martin+2007
As an accretion event: Size + metallicity of TriAnd would imply Sgr-mass progenitor Triand 1 Triand 2-2 -1.5-1 [Fe/H] -0.5 0 0.5 Sheffield+2014
Sagittarius dsph metallicity distribution (RGB stars) APOGEE survey
RR Lyrae from Catalina Sky Survey TriAnd
vgsr [km s 1 ] 150 100 50 0 50 100 P>0.8 P apple 0.8 M-giants 150 (M-giants) vgsr [km s 1 ] 150 100 50 0 50 100 (RR Lyrae) M-giants RR Lyrae 150 160 150 140 130 l [deg] 120 110 100 10 25 40 N Price-Whelan+2015
Monoceros & A13
RR Lyrae from Catalina Sky Survey Monoceros/GASS A13 TriAnd
Sheffield, Price-Whelan+2018
TriAnd, Monoceros, A13 have many K/M giants, few (if any) RR Lyrae: suggests a stellar population unlike any of the dwarf satellites of the Milky Way The Milky Way disk is metal rich: few RR Lyrae, many K/M giants - could these features have originated in the disk?
but very far from disk Johnston, Price-Whelan+2017
Detailed chemistry of A13 & TriAnd
Bergemann,,Price-Whelan+2018
0.5 0.0 [Na/Fe] -0.5-1 -3-2 -1 0 1 [Fe/H] Bergemann,,Price-Whelan+2018
0.5 Outer disk open clusters [Na/Fe] 0.0-0.5 MW disk -1-3 -2-1 0 1 [Fe/H] Bergemann,,Price-Whelan+2018
0.5 Outer disk open clusters [Na/Fe] 0.0-0.5 MW disk Sgr Fornax -1-3 -2-1 0 1 [Fe/H] Bergemann,,Price-Whelan+2018
0.5 Outer disk open clusters TriAnd / A13 [Na/Fe] 0.0-0.5 MW disk Sgr Fornax -1-3 -2-1 0 1 [Fe/H] Bergemann,,Price-Whelan+2018
3D kinematics with Gaia
TriAnd stars Rotating with the disk, slightly slower than solar circular velocity σ vr = σ vz = 25 km s 1 v ϕ = 185 km s 1 σ vϕ 50 km s 1
Summary
Summary Many of the structures identified as streams, clouds, or halo overdensities are associated with or originate from the Galactic disk, but now at extreme radii/heights above disk
Disk Accretion Eastern Banded Structure (EBS) Anticenter Stream (ACS) Monoceros / GASS Hercules-Aquila Eri-Phoenix (?) Virgo (?) TriAnd A13
Disk Talk by Chervin Laporte Eastern Banded Structure (EBS) Anticenter Stream (ACS) Monoceros / GASS Accretion Hercules-Aquila Eri-Phoenix (?) Virgo (?) TriAnd A13 This talk
Summary Many of the structures identified as streams, clouds, or halo overdensities are associated with or originate from the Galactic disk, but now at extreme radii/heights above disk These stars could have been kicked out as a result of interactions with Sagittarius and the LMC
Laporte+2017
Summary Many of the structures identified as streams, clouds, or halo overdensities are associated with or originate from the Galactic disk, but now at extreme radii/heights above disk These stars could have been kicked out as a result of interactions with Sagittarius and the LMC These features are tracers of dark matter in the outer disk, and will constrain interaction history of the Milky Way and Sagittarius
Some relevant work: Newberg+2002 Martin+2007, 2014 Sheffield, Johnston+2014 Xu, Newberg+2015 Price-Whelan, Johnston, Sheffield+2015 Li, Sheffield+2017 Laporte+2017 Johnston, Price-Whelan+2017 Bergemann, Sesar+2018 Sheffield, Price-Whelan+2018 Hayes+2018
Extra slides
TriAnd Sgr LMC SMC Kirby+2013
Kirby+2013
RR Lyrae K/M Giants
0.8 0.4 [Mg/Fe] 0.0-0.4-3 -2-1 0 1 [Fe/H] Bergemann,,Price-Whelan+2018
Bergemann,,Price-Whelan+2018