CDM Controversies. James Bullock (UC Irvine)

Transcription

1 CDM Controversies James Bullock (UC Irvine)

2 Low stellar mass: feedback can t change DM Core Cusp Tollet et al Also: Governato+12; Penarrubia+12; Garrison-Kimmel+13, Di Cintio+14

3 Low stellar mass: feedback can t change DM looks like N-body feedback makes cored halos Tollet et al M M (M ) M Also: Governato+12; Penarrubia+12; Garrison-Kimmel+13, Di Cintio+14

4 Low stellar mass: feedback can t change DM looks like N-body feedback makes cored halos Below M ~10 6 M not enough energy from supernovae to alter DM structure Tollet et al M M (M ) M Also: Governato+12; Penarrubia+12; Garrison-Kimmel+13, Di Cintio+14

5 A different feedback scheme: similar picture FIRE: Hopkins, Keres, Onorbe, Faucher-Giguere, Quataert, Murray, JSB (2014) Onorbe+2015 Black = DM only Red = With Baryons mdm ~ 1000 M mgas ~ 250 M fres ~ 10 pc MHALO=10 10 M M =2.5x10 6 M

6 Dark matter core sizes: Rcore ~= R R MHALO= M M =10 4 M MHALO=10 10 M M =(2-3)x10 6 M Onorbe+2015

7 Very low mass galaxies: no observable core Onorbe+2015 MHALO= M M =10 4 M MHALO=10 10 M M =(2-3)x10 6 M

8 Consensus: Small galaxies => cuspy/dense halos Below M ~10 6 M not enough energy from supernovae to alter DM structure => MHALO=10 10 M or Vmax~40 km/s Governato+12; Penarrubia+12; Garrison-Kimmel +13, Di Cintio+14; Tollet+15; Onorbe+15; et al. Motivates the study of dwarf galaxies

9 MISSING SATELLITES (1999) Theory: N>>1000 Klypin et al. 1999; Moore et al Observation: N~10 M ~105-7

10 MISSING SATELLITES (2015) CVnII LeoIV UMaI Sextans Ursa Minor BootesI/II Coma Segue1 W1 Draco Herc UMaII Milky Way Sag LMC Carina SMC Sculptor Fornax Theory: N>>1000 Klypin et al. 1999; Moore et al Observation: N~50 M ~103-7

11 EASY ANSWER only the biggest clumps have enough stars to see? e.g. JSB, Kravtsov, & Weinberg 2000

12 EASY ANSWER only the biggest clumps have enough stars to see? e.g. JSB, Kravtsov, & Weinberg 2000

13 EASY ANSWER

14 TOO BIG TO FAIL PROBLEM Aquarius simulations (Springel et al.) Where are these massive halos? Theory Data Boylan-Kolchin, JSB, Kaplinghat+11,12

15 TOO BIG TO FAIL PROBLEM => MHALO=10 10 M or Vmax~40 km/s At critical scale: M ~10 6 M Where are these massive halos? Aquarius simulations (Springel et al.) Theory Data Boylan-Kolchin, JSB, Kaplinghat+11,12

16 TOO BIG TO FAIL IN THE MILKY WAY Boylan-Kolchin+2012 Median: ~10 missing per Milky Way. (Garrison-Kimmel+14). Only 4 of the classical dwarfs have have Mstar > Msun Same issue is present around Andromeda galaxy (Tollerud+14) NOTE: If Milky Way is low-mass 8.e11 Msun then the problem goes away, but then existence LMC/SMC is a new problem (Jiang & vdbosch 2015)

17 TOO BIG TO FAIL IN THE LOCAL FIELD Garrison-Kimmel Boylan-Kolchin+2012 Median: ~15 missing TBTF halos in Local Field. Only 11 galaxies known, 7 w/ Mstar> ELVIS

18 WHAT ABOUT MORE DISTANT GALAXIES (~10 Mpc)? Rodrıguez-Puebla+ (2016; Bolshoi-Planck) Galaxy counts look good for Vmax>60 km/s Bolshoi / Theory HI data Vmax~60 km/s

19 WHAT ABOUT MORE DISTANT GALAXIES (~10 Mpc)? Galaxy counts look low for Vmax<40 km/s Where are these massive halos? Papastergis & Shankar 2016 Bolshoi / Theory HI data Vmax~60 km/s

20 WHAT ABOUT MORE DISTANT GALAXIES (~10 Mpc)? Benefit of the doubt: VHI may be below halo Vmax Vmax VHI Papastergis & Shankar 2016

21 WHAT ABOUT MORE DISTANT GALAXIES (~10 Mpc)? This relation DEMANDS that the counts work Papastergis & Shankar 2016

22 WHAT ABOUT MORE DISTANT GALAXIES (~10 Mpc)? Do the measured densities work out? Papastergis & Shankar 2016

23 WHAT ABOUT MORE DISTANT GALAXIES (~10 Mpc)? Do the measured densities work out? Papastergis & Shankar 2016

24 WHAT ABOUT MORE DISTANT GALAXIES (~10 Mpc)? Do the measured densities work out? Papastergis & Shankar 2016

25 TOO BIG TO FAIL IN THE FIELD Under-dense Compares to di Cintio+14 profiles that include baryon feedback (core) correction. OK Papastergis & Shankar+15 Also: Papastergis+2014; Klypin+2014

26 TOO BIG TO FAIL IN THE FIELD IMPORTANT: Comparison uses baryon-affected profiles (Di Cintio+14) Under-dense Ferrero OK R Papastergis & Shankar15 Also: Papastergis+2014; Klypin+2014

27 Many galaxies <40 km/s appear to be under-dense at very large radii > R. WHY IS THIS SO TROUBLING? Current hydro-feedback models do not affect profiles at these large radii. Ferrero R

28 TOO BIG TO FAIL SUMMARY Exists in Andromeda, Local Field, & more distant field. Solutions that appeal to Milky Way mass or Milky Way environment (Brooks+13, Arraki+13) are probably not going to work. Halos with Vmax ~ km/s (Mvir ~ Msun ) are either Less Numerous and/or Less Dense than predicted in LCDM N-body simulations Stellar mass scale approaching the point where baryon feedback may not solve problem.