completeness corrections and the small scale issues of the Milky Way Stacy Kim Small Galaxies, Cosmic Questions | Durham, UK | July 29, 2019 GAIA DR1 sky map
Two fundamental predictions of CDM 1 DM halos are cuspy in � their centers, i.e. CDM � (“cuspy”) density 2 observed Nearly scale-free � (“cored”) hierarchy of DM halos to Earth-mass scales! radius cusp-core problem missing satellites problem
substructure a fundamental prediction of CDM Garrison-Kimmel+ 2017
substructure a fundamental prediction of CDM DM only simulations of the Milky Way O(100) satellites Garrison-Kimmel+ 2017
observed Leo II Leo I Ursa Minor Sextans Draco Sagittarius Carina LMC SMC ~10 satellites! Sculptor Fornax GAIA DR1 sky map
observed Leo II Leo I Ursa Minor Sextans Draco Sagittarius Carina LMC SMC ~10 satellites! Sculptor Fornax missing satellites problem GAIA DR1 sky map
observed Leo II Leo I Ursa Minor Sextans Draco Sagittarius Carina LMC SMC ~27 post-SDSS Sculptor Fornax GAIA DR1 sky map
observed Leo II Leo I Ursa Minor Sextans Draco Sagittarius Carina LMC SMC ~44 with DES Sculptor Fornax GAIA DR1 sky map
observed Leo II Leo I Ursa Minor Sextans Draco Sagittarius Carina LMC SMC ~50 with DES Sculptor Fornax + a few others GAIA DR1 sky map
where’s the rest? Tollerud+ 2008
where’s the rest? Milk ilky y Way y radiu ius Tollerud+ 2008
where’s the rest? visib isible le Tollerud+ 2008
where’s the rest? in invisib isible le visib isible le Tollerud+ 2008
where’s the rest? in invisib isible le visib isible le MW sa satellit ellites es � we e ca can’t see see Tollerud+ 2008
completeness corrections
completeness corrections radial distribution 1 (plotted as a CDF) percent observed within r 0 r (kpc)
completeness corrections for each dwarf observed, with brightness M V , radial distribution completeness � 1 (plotted as a CDF) radius R(M V ) percent observed within r 0 r (kpc)
completeness corrections for each dwarf observed, with brightness M V , radial distribution completeness � 1 (plotted as a CDF) radius R(M V ) percent observed within r f 0 r (kpc)
completeness corrections for each dwarf observed, with brightness M V , radial distribution completeness � 1 (plotted as a CDF) radius R(M V ) percent observed within r 1 f total dwarfs 1 f 0 r (kpc)
completeness corrections for each dwarf observed, with brightness M V , radial distribution completeness � 1 (plotted as a CDF) radius R(M V ) percent observed within r radial 1 completeness f total dwarfs 1 f correction 0 r (kpc)
completeness corrections for each dwarf observed, with brightness M V , radial distribution completeness � 1 (plotted as a CDF) radius R(M V ) percent observed within r radial 1 completeness total dwarfs 1 f f correction 0 r (kpc) area A sky completeness A correction survey area
completeness corrections for each dwarf observed, with brightness M V , radial distribution completeness � 1 (plotted as a CDF) radius R(M V ) percent observed within r radial 1 completeness total dwarfs 1 f f correction 0 r (kpc) area A sky completeness total dwarfs � 1 A sky A = correction 1 with M V f A survey area
completeness corrections for each dwarf observed, with brightness M V , radial distribution completeness � 1 (plotted as a CDF) radius R(M V ) percent observed within r radial 1 completeness total dwarfs 1 f f correction 0 r (kpc) area A sky sum for � completeness total dwarfs � 1 A sky A each dwarf, � = correction 1 with M V f A MW total survey area
completeness corrections for each dwarf observed, with brightness M V , radial distribution completeness � 1 (plotted as a CDF) radius R(M V ) percent observed within r radial No missing satellites! 1 completeness total dwarfs 1 (Kim+ 2018) f f correction 0 r (kpc) area A sky sum for � completeness total dwarfs � 1 A sky A each dwarf, � = correction 1 with M V f A MW total survey area
completeness corrections for each dwarf observed, with brightness M V , dispersion σ * , radial distribution completeness � 1 (plotted as a CDF) radius R(M V ) percent observed within r radial 1 completeness total dwarfs 1 f f correction 0 r (kpc) area A sky sum for � completeness total dwarfs � 1 A sky A each dwarf, � = correction 1 with σ * f A MW total survey area
radial distributions 10 0 Segue I 10 − 1 N( < r)/N total NFW SIS 10 − 2 ELVIS, stripped D17 DMO + gal DMO + gal 10 − 3 + GK17 stripping 10 1 10 2 r (kpc)
corrected velocity function
predictions from simulations
predictions from simulations to capture suppresion in MF in hydrodynamic simulations
predictions from simulations luminous subhalos galaxies unsuppressed � by reionization Dooley+ 2017, Barber+ 2014
predictions from simulations converting M halo σ *
predictions from simulations Wolf+ 2010 mass estimator M ( < r 1 / 2 ) ∗ ⟩ = G ⟨ σ 2 4 R 1 / 2 converting M halo σ *
predictions from simulations Wolf+ 2010 mass estimator M ( < r 1 / 2 ) ∗ ⟩ = G ⟨ σ 2 4 R 1 / 2 Danielli+ 2018 converting M halo σ *
predictions from simulations Wolf+ 2010 mass estimator calculate for different M ( < r 1 / 2 ) ∗ ⟩ = G density profiles ⟨ σ 2 r 1/2 4 R 1 / 2 cuspy Danielli+ 2018 density cored radius converting M halo σ *
theory vs. observations
theory vs. observations added effect of tidal stripping Penarrubia+ 2010
theory vs. observations requires cusps to explain velocity function!
theory vs. observations too many satellites if severity of disk stripping to be believed! requires cusps to explain velocity function!
implications for SIDM suggests SIDM constraints of σ * /m ~ 0.3 cm 2 /g!
corrected velocity function transition from cores to cusps at 10 10 M ¤ Read+2016, Robles+ 2017
observational uncertainties older velocity measurements for the satellite galaxy Boo II 10.5 ± 7.4 km/s --> 4.4 ± 1.1 km/s Geha+, private communication
observational uncertainties reducing uncertainties on velocity measurements by a factor of 2 Geha+, private communication
observational uncertainties reducing uncertainties on velocity measurements by a factor of 2 shape of the velocity function sensitive to uncertainties! Geha+, private communication
velocity functions: a summary CDM with baryons does a decent job � explaining satellite kinematics but too many satellites with disk stripping
velocity functions: a summary CDM with baryons does a decent job � explaining satellite kinematics but too many satellites with disk stripping SIDM with σ * /m > 0.3 cm 2 /g disfavored
velocity functions: a summary CDM with baryons does a decent job � explaining satellite kinematics but too many satellites with disk stripping SIDM with σ * /m > 0.3 cm 2 /g disfavored shape of corrected velocity function strongly dependent velocity uncertainties more precise measurements needed!
EXTRAS: MSP
corrected luminosity function 10 3 observed observed + area cor. NFW SIS 10 2 ELVIS, stripped N sats > M ⇤ D17 DMO + gal DMO + gal 10 1 + GK17 stripping Behroozi+ 2013 Behroozi+ 2013 Moster+ 2013 Moster+ 2013 Brook+ 2014 Brook+ 2014 10 0 10 3 10 4 10 5 10 6 10 7 10 8 10 9 M ⇤ (M � )
corrected luminosity function 10 3 observed observed + area cor. NFW SIS 10 2 ELVIS, stripped N sats > M ⇤ D17 DMO + gal DMO + gal 10 1 + GK17 stripping z re = 9.3 z re = 9.3 z re = 11.3 z re = 11.3 z re = 14.4 z re = 14.4 10 0 10 3 10 4 10 5 10 6 10 7 10 8 10 9 M ⇤ (M � )
dependence on reionization redshift 10 11 CDM WDM, 8.0 keV WDM, 4.0 keV 10 10 WDM, 2.0 keV infall mass (M � ) WDM, 1.0 keV 10 9 Brook+ 2014 Moster+ 2013 10 8 10 7 Behroozi+ 2013 10 0 10 1 10 2 10 3 cumulative number of satellites < M infall
mass of Segue I z = 9.3 h M z =0 i / M � 10 6 10 7 10 8 MSP NFW SIS ELVIS, stripped DMO + gal DMO + gal, not enough subhalos GK17 stripping 10 6 10 7 10 8 10 9 Lowest mass galaxy halo (M infall /M � )
mass of Segue I z = 11.3 h M z =0 i / M � 10 6 10 7 10 8 MSP NFW SIS ELVIS, stripped DMO + gal DMO + gal, not enough subhalos GK17 stripping 10 6 10 7 10 8 10 9 Lowest mass galaxy halo (M infall /M � )
mass of Segue I z = 14.4 h M z =0 i / M � 10 6 10 7 10 8 MSP NFW SIS ELVIS, stripped DMO + gal DMO + gal, not enough subhalos GK17 stripping 10 6 10 7 10 8 10 9 Lowest mass galaxy halo (M infall /M � )
velocity dispersions, σ * less massive subhalo more massive subhalo
velocity dispersions, σ * less massive subhalo more massive subhalo
velocity dispersions, σ * less massive subhalo more massive subhalo Stars in more massive subhalos orbit faster � (to counteract gravity), thus velocities a proxy for mass!
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