Satellites of satellites: LCDM predictions for the satellite population of M33 Credit: NASA, ESA, and M. Durbin, J. Dalcanton, and B. F. Williams (University of Washington) Ekta Patel 1,2 , Jeff Carlin 3 , Erik Tollerud 4 , Michelle Collins 5 , Greg Dooley 6 1 U. Arizona, 2 UC Berkeley - Miller Institute, 3 LSST, 4 STScI, 5 U. Surrey, 6 Google
Satellites in MW-Mass Halos theory Single LSST: 93-179 sats DES: 19-37 sats Tollerud+08; see also Newton+18 Ekta Patel U. Arizona/Berkeley
Satellites in MW-Mass Halos observations theory Single LSST: 93-179 sats DES: 19-37 sats Tollerud+08; see also Newton+18 Crnojevi ć +19; see also Bennet+19 Ekta Patel U. Arizona/Berkeley
Satellites in MW-Mass Halos observations theory Single LSST: 93-179 sats 100 MW-mass analogs at completion! DES: 19-37 sats Tollerud+08; see also Newton+18 SAGA; Geha+17 Ekta Patel U. Arizona/Berkeley
Satellites in 10 11 M ⦿ Halos It becomes increasingly difficult to search for satellites around sub-MW mass haloes (< 10 11 M ⦿ ) as many satellites are in the ultra-faint regime. The LMC(+SMC) is the nearest example to test predictions. Dooley+17b Sales+13: 1 SMC, 5-40 ultra- faint dwarf galaxies (UFDs): M � ∼ (0.1–1) × 10 4 M ⦿ Dooley+17b: 2-12 UFDs with M � > 10 4 M ⦿ See also Jethwa+16, Kallivayalil+18 (and reference within) (see also D’Onghia & Lake 08, Sales+13, Li & Helmi 2008) Ekta Patel U. Arizona/Berkeley
Satellites in 10 11 M ⦿ Halos It becomes increasingly difficult to search for satellites around sub-MW mass haloes (< 10 11 M ⦿ ) as many satellites are in the ultra-faint regime. The LMC(+SMC) is the nearest example to test predictions. Dooley+17b Sales+13: 1 SMC, 5-40 ultra- faint dwarf galaxies (UFDs): M � ∼ (0.1–1) × 10 4 M ⦿ Dooley+17b: 2-12 UFDs with M � > 10 4 M ⦿ See also Jethwa+16, Kallivayalil+18 (and reference within) Credit: V. Belokurov, S. Koposov (IoA, Cambridge). Photo: Y. Beletsky (Carnegie Observatories) (see also D’Onghia & Lake 08, Sales+13, Li & Helmi 2008) Ekta Patel U. Arizona/Berkeley
M33: M31’s Most Massive Satellite Galaxy Ekta Patel U. Arizona/Berkeley
M33: M31’s Most Massive Satellite Galaxy M � = 3.2 x 10 9 M ⦿ → M halo ~10 11 M ⦿ • isolated LMC counterpart • 200 kpc from M31 • ~10% of M31’s mass • morphology shows hints of previous • interaction(s) in gas and stars: M31 or satellite companions? Ekta Patel U. Arizona/Berkeley
M33: M31’s Most Massive Satellite Galaxy M � = 3.2 x 10 9 M ⦿ → M halo ~10 11 M ⦿ • isolated LMC counterpart • 200 kpc from M31 • ~10% of M31’s mass • morphology shows hints of previous • interaction(s) in gas and stars: M31 or satellite companions? Ekta Patel U. Arizona/Berkeley
M33’s Conventional 0 Orbital History: M33 − 200 Prior to 2012, M31’s proper M31 motion (i.e. its tangential motion) was unknown . − 400 kpc t peri = 2.6 Gyr ago r peri = 55 kpc What orbital history best PREVIOUS: − 600 recent peri reproduces M33’s current PAndAS; morphology? − 800 McConnachie+09 − 1000 − 200 0 200 400 kpc Ekta Patel U. Arizona/Berkeley
A New Orbital History for M33 Which orbital histories are allowed within the measured phase space? 0 • 10,000 backwards M33 numerical integrations x 6 different mass models − 200 M31 − 400 kpc t peri = 2.6 Gyr ago r peri = 55 kpc PREVIOUS: − 600 recent peri PAndAS; − 800 McConnachie+09 − 1000 − 200 0 200 400 kpc Ekta Patel U. Arizona/Berkeley
A New Orbital History for M33 Which orbital histories are allowed within the measured phase space? t peri = ~6 Gyr ago r peri = ~100 kpc 0 • 10,000 backwards M33 numerical integrations x 6 different mass models − 200 M31 • < 1% of M33 orbits − 400 kpc t peri = 2.6 Gyr ago reach R peri = 55-100 kpc r peri = 55 kpc HST + VLBA PMs with t peri ≤ 3 Gyr (Patel+17a) PREVIOUS: − 600 recent peri PAndAS; − 800 McConnachie+09 Gaia DR2 + HST + VLBA PMs (van der Marel+ w/ Patel, 2019) − 1000 − 200 0 200 400 kpc Ekta Patel U. Arizona/Berkeley
A New Orbital History for M33 Which orbital histories are allowed within the measured phase space? t peri = ~6 Gyr ago r peri = ~100 kpc 0 • 10,000 backwards M33 numerical integrations x 6 different mass models − 200 M31 • < 1% of M33 orbits − 400 kpc t peri = 2.6 Gyr ago reach R peri = 55-100 kpc r peri = 55 kpc HST + VLBA PMs with t peri ≤ 3 Gyr (Patel+17a) PREVIOUS: − 600 NEW: recent peri first infall PAndAS; • Gaia DR2 PMs further − 800 McConnachie+09 Gaia DR2 + HST + VLBA PMs support first infall (van der Marel+ w/ Patel, 2019) − 1000 − 200 0 200 400 kpc Ekta Patel U. Arizona/Berkeley
LCDM Predictions for M33’s Satellite Population Applying techniques of Dooley+17a,b Dark matter only Caterpillar suite: 33 MW-mass zooms (m p ~ 10 4 M ⦿ ) host galaxy Ekta Patel U. Arizona/Berkeley
LCDM Predictions for M33’s Satellite Population Applying techniques of Dooley+17a,b Dark matter only Caterpillar suite: 33 MW-mass zooms (m p ~ 10 4 M ⦿ ) 1. Determine the subhalo mass function (SHMF) for host galaxy host galaxies Ekta Patel U. Arizona/Berkeley
LCDM Predictions for M33’s Satellite Population Applying techniques of Dooley+17a,b Dark matter only Caterpillar suite: 33 MW-mass zooms (m p ~ 10 4 M ⦿ ) 1. Determine the subhalo mass function (SHMF) for host galaxy host galaxies 2. Sample SHMF to generate random realization of DM subhalos for host Ekta Patel U. Arizona/Berkeley
LCDM Predictions for M33’s Satellite Population Applying techniques of Dooley+17a,b Dark matter only Caterpillar suite: 33 MW-mass zooms (m p ~ 10 4 M ⦿ ) 1. Determine the subhalo mass function (SHMF) for host galaxy host galaxies 2. Sample SHMF to generate random realization of DM subhalos for host 3. Model reionization by assigning which subhalos remain dark Ekta Patel U. Arizona/Berkeley
LCDM Predictions for M33’s Satellite Population Applying techniques of Dooley+17a,b 4. Assign stellar masses Dark matter only Caterpillar suite: 33 MW-mass zooms via M � - M halo relation (m p ~ 10 4 M ⦿ ) (Garrison-Kimmel+17) 1. Determine the subhalo mass function (SHMF) for host galaxy host galaxies 2. Sample SHMF to generate random realization of DM subhalos for host 3. Model reionization by assigning which subhalos remain dark Ekta Patel U. Arizona/Berkeley
LCDM Predictions for M33’s Satellite Population Applying techniques of Dooley+17a,b 4. Assign stellar masses Dark matter only Caterpillar suite: 33 MW-mass zooms via M � - M halo relation (m p ~ 10 4 M ⦿ ) (Garrison-Kimmel+17) 1. Determine the subhalo mass function (SHMF) for host galaxy host galaxies 2. Sample SHMF to generate random realization of DM M33 properties: subhalos for host R vir = 161 kpc M vir = 2.5 ⨉ 10 11 M ⦿ 3. Model reionization by assigning which subhalos remain dark Ekta Patel U. Arizona/Berkeley
LCDM Predictions for M33’s Satellite Population* *corrected for geometric effects 150 kpc PAndAS 100 kpc 50 kpc 50 100 161 PAndAS observed ~40% of M33’s virial volume and one candidate satellite was identified (M V ~ -6.5). Ekta Patel U. Arizona/Berkeley
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