Where to Look for Dark Matter Weirdness

Transcription

1 Where to Look for Dark Matter Weirdness Dark Matter in Southern California (DaMaSC) - II James Bullock UC Irvine Garrison-Kimmel, Oñorbe et al.

2 Collaborators Mike Boylan-Kolchin U. Maryland Miguel Rocha Shea Garrison-Kimmel Oliver Elbert Manoj Kaplinghat Annika Peter The Ohio Sate University Jose Oñorbe MPIA Heidelberg

3 Outline 1. Dwarf Galaxies and the Too Big to Fail Problem 2. Baryon Physics vs. Dark Matter Physics - SIDM with σ/m ~ (0.5-1) cm 2 /g can solve the problem - Feedback probably can t solve it, environment an issue. 3. Baryons + SIDM = Harder than we hoped (but fun) 4. Future directions

4 Smallest Dwarfs: Great DM Laboratories M? 10 6 M r? 500pc M DM M? 50 Dark Matter Dominated => Easy to interpret Very Few Stars => SN Can t Alter DM

5 Best-studied dwarfs are satellites of MW Simulated MW Halo Bright Satellites of the MW L>10 5 Lsun Garrison-Kimmel, JSB, Boylan-Kolchin

6 Biggest subhalos = brightest satellites? Image: Garrison-Kimmel

7 How do the masses compare? Image: Garrison-Kimmel

8 All bright MW dsphs (L>10 5 Lsun) 8 biggest subhalos (remove LMC/SMC analogs) 8 biggest subhalos are too dense to host ANY of MW dsph satellites Boylan-Kolchin, JSB, Kaplinghat 2011,2012

9 Too Big to Fail Problem 8 biggest subhalos (remove LMC/SMC analogs) 8 biggest subhalos are too dense to host ANY of MW dsph satellites Boylan-Kolchin, JSB, Kaplinghat 2011,2012

10 Summary of the Too Big To Fail problem: Boylan-Kolchin, JSB, Kaplinghat 2012 Expect 5-40 subhalos with Vmax >25 km/s (from 48 simulations) Garrison-Kimmel et al. in prep

11 Summary of the Too Big To Fail problem: Boylan-Kolchin, JSB, Kaplinghat 2012 Why nothing here? Expect 5-40 subhalos with Vmax >25 km/s (from 48 simulations) Garrison-Kimmel et al. in prep

12 What Can Baryons Do?? Consider a M* ~10 6 Msun dwarf galaxy What does it take to remove enough DM?

13 Basic Energy Argument Against SN Feedback M? 10 6 M M DM M Must remove ~50 times more dark matter than mass in stars! Energy Required: > ergs Exceeds every supernovae that has gone off coupled directly to the dark matter. Penarrubia et al. 2012; Garrison-Kimmel et al. 2013

14 Oñorbe et al. (in prep) Minimal change in DM density Jose Oñorbe Use P-GADGET SPH - Overcomes most standard SPH issues - Feedback of Hopkins, Quartaert, and Murray (2012) Dark Matter Only Full Hydrodynamics M* ~ 10 6 Msun Not converged numerically mdm = 1200Msun mgas = 250Msun ε dm = 40pc Z=0 Stats: Abundance Matching [GOOD] Fe/H ~ -2.5 [GOOD] Mgas/M* ~ 0.1 [OK]

15 Baryonic Feedback: Not so effective for M* < 10 7 Log slope density profile CORE Data CDM-only prediction Simulations with feedback CUSP Governato et al. 2012

16 Baryonic Feedback: Not so effective for M* < 10 7 CORE Log slope density profile M*< 10 7 Msun: very little change in DM prediction Data CDM-only prediction Simulations with feedback CUSP Governato et al. 2012

17 Is there a baryonic solution to Too Big to Fail? SN Feedback alone: No Why nothing here? - Not Enough Energy: hard to affect densities with < 10 6 Msun of stars (<10 4 SN) Garrison-Kimmel et al. 2013; Governato et al. 2012; Penarrubia et al Environment: best bet - Tidal forces (extra from disk) and ram-pressure stripping provide additional sources of energy to remove DM Brooks & Zolotov 2012; Zolotov et al. 2012; Arraki et al. 2012

18 What s next? Extend these studies to the field (no ram-pressure or tides) Ferrero, Abadi,Navarro, Sales, & Gurovich Examine rotation curves of field dwarfs with Mgal~ Msun - Same problem: not dense enough - Hard to reconcile with DM halo mass function + observed lum function Abstract:... Resolving this challenge seems to require new insights into dwarf galaxy formation, or perhaps a radical revision of the prevailing paradigm.

19 Beyond Cold Dark Matter? Warm Dark Matter: Self-interacting Dark Matter: CDM WDM CDM SIDM Lovell et al Vogelsberger et al m dm kev /m dm 1cm 2 /g Lovell et al Vogelsberger et al. 2011, 2012; Rocha et al. 2012; Peter et al. 2012; Spergel & Steinhardt (2000)

20 Simula'ng Self- interac'ng DM Scattering rate: = dm m v rms For now: Elastic, Velocity Independent, Isotropic Interesting things happen when H 0 m 1cm2 /g Miguel Rocha Annika Peter Manoj Kaplinghat

21 Rocha et al IdenGcal large- scale structure Λ+CDM Λ+SIDM σ/m = 1 cm 2 /g

22 Rocha et al Λ+CDM Λ+SIDM σ/m = 1 cm 2 /g

23 Rocha et al SIDM: Rounder, lower- density cores. (substructure counts minimally affected) Λ+CDM Λ+SIDM σ/m = 1 cm 2 /g

24 Density Cold Dark Matter SIDM Makes Cored Halos SIDM: σ/m=1cm 2 /g Rocha et al radius

25 SIDM Makes Cored Halos Density Cold Dark Matter Velocity Dispersion SIDM: σ/m=1cm 2 /g SIDM: σ/m=1cm 2 /g Cold Dark Matter Rocha et al radius radius Isothermal velocity profile creates core.

26 Fully cosmological zoom of isolated dwarf halo: Vmax~35km/s CDM SIDM: σ/m=0.5cm 2 /g SIDM: σ/m=1cm 2 /g SIDM: ~ 500 pc cores w/ densities ~0.1 Msun/pc 3 - Both values match dsph observations (Strigari et al. 08; Walker & Penarrubia 12) Mass resolution: 1200 Msun (DM) Force resolution: 40 pc Elbert et al., in preparation

27 SIDM with σ/m=(0.5-1)cm 2 /g Solves Too Big To Fail Problem SIDM: σ/m=0.5cm 2 /g CDM UrsMin Draco Leo I SIDM: σ/m=1cm 2 /g Elbert et al., in preparation.

28 Galaxy Clusters as a Probe of SIDM?

29 Less than cuspy cluster cores? Newman,Treu, Ellis, & Sand

30 Cosmological Sim of a Galaxy Cluster: Msun CDM SIDM σ/m=0.1 cm 2 /g SIDM σ/m=0.5cm 2 /g SIDM σ/m=1cm 2 /g Rocha et al., in prep.

31 Cosmological Sim of a Galaxy Cluster: Msun CDM SIDM σ/m=0.1 cm 2 /g ρcore ~ M sun /kpc 3 SIDM σ/m=0.5cm 2 /g SIDM σ/m=1cm 2 /g Rocha et al., in prep.

32 SIDM σ/m=0.5cm 2 /g ρcore ~ M sun /kpc 3 Newman,Treu, Ellis, & Sand

33 What Do Baryons Do??

34 SIDM vs. CDM (no baryonic component) Final CDM halo (10 Gyr) Initial CDM halo 0 Gyr 0.0 Gyrs Baryon10.0 Potential Gyrs 10 Gyr CDM Density [M /pc 3 ] Initial CDM halo Run with SIDM for 10 Gyr Galaxy (grown slowly) 10 4 Elbert et al., in preparation Radius [pc]

35 SIDM vs. CDM (no baryonic component) Density [M /pc 3 ] CDM SIDM 0.0 Gyrs 10.0 Gyrs Initial CDM halo Velocity Dispersion [km/s] SIDM CDM 0.0 Gyrs 10.0 Gyrs Radius [pc] Radius [kpc] Elbert et al., in preparation

36 SIDM vs. CDM (no baryonic component) Final CDM halo (10 Gyr) Initial CDM halo 0 Gyr 0.0 Gyrs Baryon10.0 Potential Gyrs 10 Gyr CDM Density [M /pc 3 ] Initial CDM halo Run with SIDM for 10 Gyr Galaxy (grown slowly) 10 4 Elbert et al., in preparation Radius [pc]

37 e.g. Blumenthal et al Simulating Baryonic Contraction Galaxy (grown slowly) Final CDM halo 0 Gyr Baryon Potential 10 Gyr CDM Density [M /pc 3 ] Initial CDM halo 10 4 Elbert et al., in preparation Radius [pc]

38 e.g. Blumenthal et al Simulating Baryonic Contraction Galaxy (grown slowly) Final CDM halo 0 Gyr Baryon Potential 10 Gyr CDM Density [M /pc 3 ] Initial CDM halo 10 4 Elbert et al., in preparation Radius [pc]

39 Baryons + SIDM Galaxy (grown slowly) Final SIDM halo Final CDM halo halo 0 Gyr 0 Gyr Baryon 10 Gyr Potential CDM 10 Gyr 10 Gyr CDMSIDM Density [M /pc 3 ] Initial halo Initial CDM halo 10 4 Elbert et al., in preparation Radius [pc]

40 Baryons + SIDM Galaxy (grown slowly)!! Final SIDM halo Final CDM halo halo 0 Gyr 0 Gyr Baryon 10 Gyr Potential CDM 10 Gyr 10 Gyr CDMSIDM Density [M /pc 3 ] Initial halo Initial CDM halo 10 4 Elbert et al., in preparation Radius [pc]

41 Baryons make SIDM predictions complicated Density [M /pc 3 Density [M /pc 3 ] Galaxy (grown slowly) 0 Gyr 0 Gyr 0 Gyr SIDM + contraction 10 Gyr CDM Baryon 10 Gyr Potential CDM Final SIDM halo 10 Gyr SIDM 10 Gyr 10 Gyr CDMSIDM CDM + contraction Final CDM halo halo 10 Gyr SIDM, no potential Initial Initial halo Initial CDM halo SIDM (No galaxy) Elbert et al., in preparation Radius [pc]

42 SIDM + Baryons = Hard (~CDM + Baryons) 250 SIDM + contraction Velocity Dispersion [km/s] CDM + contraction SIDM (No galaxy) Initial Radius [kpc] 0 Gyr 10 Gyr CDM 10 Gyr SIDM 10 Gyr SIDM, no potential Elbert et al., in preparation

43 SIDM + Baryons = Hard (~CDM + Baryons) Size of SDM core will relate to baryonic distribution 250 SIDM + contraction Velocity Dispersion [km/s] CDM + contraction SIDM (No galaxy) Initial Radius [kpc] 0 Gyr 10 Gyr CDM 10 Gyr SIDM 10 Gyr SIDM, no potential Elbert et al., in preparation

44 Smallest Dwarfs: Great DM Laboratories M? 10 6 M r? 500pc M DM M? 50 Dark Matter Dominated => Easy to interpret Very Few Stars => SN Can t Alter DM

45 The Local Volume is the Next Frontier Observation Theory Masses of LG dwarfs Evan Kirby et al., in prep Simulating Local Groups... Garrison-Kimmel et al., in prep

46 ELVIS [Exploring the Local Volume In Simulations] Garrison-Kimmel, Boylan-Kolchin, JSB

47 1. The Too Big to Fail Problem Take-Aways Satellites of MW have lower dark matter densities than expected. - Where are the most massive/dense subhalos? 2. Possible solutions - SN Feedback? Not enough stars to do it. - Any Baryonic process? Could be environmental - test w/ obs of isolated dwarfs - Dark Matter physics? - SIDM with σ/m ~ cm 2 /g can do it. 3. Where to look for DM weirdness? Baryon-dominated systems are interesting in SIDM but HARD Dark matter dominated dsph s in the Local Field may be the best bet.

48 The Local Volume Looks Problematic too ELVIS Garrison-Kimmel et al. 2013b Expect ~ dense galaxies with Vmax>30 km/s!

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50 Massive Galaxy Cluster: Msun CDM SIDM σ/m=0.1 cm 2 /g SIDM σ/m=0.5cm 2 /g SIDM σ/m=1cm 2 /g SIDM: substructure affected at factor of ~2 level max Rocha et al., in prep. Subhalo mass (M sun )

51 Dark Matter Phenomenology: Substructure CDM SIDM (dashed) # of MW satellites > 20 WDM m s = 6 KeV Horiushi et al. WDM: - Solves Too Big To Fail by removing offending subhalos all together. Problem: - For models that solve the TBTF: not enough subhalos to explain known satellite count - Same models also struggle to explain Ly-alpha forest clumping CDM SIDM WDM

52 Expect: 0.01 Supernova per solar mass of stars. Req. more energy than sum of all supernovae in this galaxy! Slightly more energy input unbinds the halo all together (fine-tuning problem) # of SN worth of energy Garrison-Kimmel et al. 2013a Energy Required