Credit: Alex Drlica-Wagner and DES

The Southern Stellar Stream Spectroscopic Survey (S5) and Beyond

Ting LiLeon Lederman Fellow, Fermilab

KICP Associated Fellow, the University of Chicago

Massively multiplexed spectroscopy with MSE, 26-28 February, 2019, Tucson, AZ

Field of Streams in the Dark Energy Survey (DES) Footprint

Shipp et al. (2018)w/ TSL(DES Collaboration)

The Southern Stellar Stream Spectroscopic Survey (S5) and Beyond

Ting LiLeon Lederman Fellow, Fermilab

KICP Associated Fellow, the University of Chicago

S5 Collaboration

• DES Milky Way• Ting Li* (co-PI)• Kyler Kuehn*• Nora Shipp• Andrew Pace• Alex Drlica-Wagner• Vasily Belokurov• Jennifer Marshall• Sahar Allam• Douglas Tucker• Eduardo Balbinot• Keith Bechtol• Kathy Vivas• Risa Wechsler• Brian Yanny

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• Australians• Daniel Zucker* (co-PI)• Geraint Lewis*• Jeffrey Simpson• Gary Da Costa• Dougal Mackey• Sarah Martell• Gayandhi De Silva• Zhen Wan• Jeremy Mould• Andrew Casey• Joss Bland-Hawthorn• Ken Freeman• Prajwal Kafle• Sanjib Sharma• Helmut Jerjen

• DES external collaborators• Denis Erkal• Sergey Koposov• Marla Geha• Josh Simon• Yao-Yuan Mao• Alexander Ji

* S5 Leadership

S5 is an international collaboration of ~30 members

Introduction

• Why Stellar Streams?• Formation of Galactic Halo• Milky Way’s Gravitational Potential• Dark Matter Subhalo Distribution

• Modern imaging surveys have discovered 50+ streams in the Milky Way (e.g., Mateu et al. 2018, Shipp et al. 2018)

• ~7 streams has been followed up spectroscopically.

• Spectroscopic follow-up observations• important;• but extremely difficult 4

High Multiplexity, wide FOV: AAT/2df+AAOmega

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AAT: Anglo-Australian Telescope (4 meter) at

Siding Spring Observatory

2df: 2-deg (in diameter) field fiber positioner w/ 400 fibers

Large Field-of-View, High Multiplexity= An Ideal Instrument for Stellar Streams Follow-ups

AAOmega: a dual-arm optical

spectrograph

• Started in August 2018• Goals: S5 + Gaia + DES =

6D + [Fe/H] for 14 DES streams

• ~25 nights in 2018B• 10 DES streams fully

mapped; 8 streams are reduced and confirmed

• Expand beyond DES footprint in 2019 for a total of 20 streams

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S5 : Overview and Status

Already double the number of streams with

6D info.

Li et al. in prep

Credit: Nora Shipp

• Line-of-sight velocities

• Proper motions (Gaia DR2)

• Metallicities• Orbits• Chemical

Abundance (high-resolution follow-up)

• Progenitors• ….

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Example: ATLAS Stream (w/ 12 AAT pointings)

Li et al. in prep

Orphan Stream inferred from RR Lyraes in Gaia DR2

Perturbation from LMC

Koposov et al. 2019 (w/ TSL), 1812.08172Erkal et al. 2019 (w/ TSL), 1812.08192(The OATs: Orphan Aspen Treasury Collaboration)

Perturbation from LMC

• Most Southern Streams were affected by LMC

• Simultaneous fit with multiple streams can infer the 3D profile of LMCCredit: Denis Erkal

Preliminary

Summary

S5 is a Spectroscopic Survey of the Southern Stellar Streams; a collaboration of ~30 scientists.Goals:

•Measure 6D + metallicity•Characterize stream progenitors•Constrain the Milky Way mass•Assess the influence of the LMC

Current Status:•25 AAT nights in 2018B•10 DES streams observed, w/ 8 reduced & confirmed•Accomplish a total of 20 streams w/ Dec < +30 deg by the end of 2019

Auxiliary Programs:•S5-Halo Survey (RR Lyrae, BHB, metal-poor stars, white dwarfs, etc.)•S5 -LOWZ Survey (dwarf galaxies at z < 0.05)•High resolution spectroscopy w/ Magellan/MIKE

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Looking Forward

Stream at 10-30 kpc:• Discovery: DES (4m), w/ MSTO stars at g < 22.5• Proper Motion: Gaia DR2, w/ RGB at g < 19.5• RV+FeH: S5 (AAT, 4m), w/ RGB at g < 19.5• Chemical abundance: S5 (Magellan, 6.5m), w/ TRGB at g < 18

Streams at 40-100 kpc:• Discovery: LSST (8m), w/ MSTO stars at g < 25.5• Proper Motion: Gaia (5yr)/WFIRST/LSST, w/RGB at g < 22.5• RV+FeH: MSE (11.25m), w/ RGB at g < 22.5• Chemical abundance: MSE/GMT/TMT, w/ TRGB at g < 20

Looking Forward

Stream at 10-30 kpc:• Discovery: DES (4m), w/ MSTO stars at g < 22.5• Proper Motion: Gaia DR2, w/ RGB at g < 19.5• RV+FeH: S5 (AAT, 4m), w/ RGB at g < 19.5• Chemical abundance: S5 (Magellan, 6.5m), w/ TRGB at g < 18• RV+FeH: MSE, w/ MSTO at g < 22.5• Chemical abundance: MSE, w/ RGBs at g < 20

Streams at 40-100 kpc:• Discovery: LSST (8m), w/ MSTO stars at g < 25.5• Proper Motion: Gaia (5yr)/WFIRST/LSST, w/RGB at g < 22.5• RV+FeH: MSE (11.25m), w/ RGB at g < 22.5• Chemical abundance: MSE/GMT/TMT, w/ TRGB at g < 20

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backup slides

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• Started in August 2018

• Goals: S5 + Gaia = 6D + [Fe/H] for all DES streams

• Targets with 15 < g < 20• photometry: DES DR1 • proper motion: Gaia DR2

• RV precision ~ 1km/s at high S/N• ~2hr exposure per field, with S/N ~ 5

at g ~ 18.5 in the red

S5 Overview

S5 is more than a stream survey!

• S5 - Stream (150/400)• S5 - Halo (150/400)

• Blue Horizontal Branch Stars• RR Lyrae Stars• Metal-Poor Stars• Low Proper Motion Stars

• S5 - LowZ (100/400)• Dwarf Galaxies in Low Redshift (z < 0.05)• w/ color and morphology selection

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Perturbation from LMC

Offsets between the tracks and the proper motions of the streams.

Shipp et al. in prep

Preliminary

• Most Southern Streams were affected by LMC