Solving Too Big to Fail: Baryon or Dark Matter Physics?
Solving Too Big to Fail: Baryon or Dark Matter Physics?
Solving Too Big to Fail: Baryon or Dark Matter Physics?
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<strong>Solving</strong> <strong>Too</strong> <strong>Big</strong> <strong>to</strong> <strong>Fail</strong>:<strong>Baryon</strong>ic <strong>or</strong> <strong>Dark</strong> <strong>Matter</strong> <strong>Physics</strong>?CDM SIDM WDMImages: M. RochaJames BullockJames BullockUC IrvineJ. Bullock, UC Irvine
Collab<strong>or</strong>a<strong>to</strong>rsShea Garrison-KimmelOliver ElbertJose Oñ<strong>or</strong>beJ. Bullock, UC Irvine
Outline1. Can Supernova Feedback Fix Dwarf Densities?- Unlikely in the smallest dwarfs (Mstar
Smallest Dwarfs: Great DM Lab<strong>or</strong>a<strong>to</strong>riesM ? ⇠ 10 6 Mr ? ⇠ 500pcM DMM ?⇠ 50<strong>Dark</strong> <strong>Matter</strong> Dominated => Easy <strong>to</strong> interpretVery Few Stars => SN Can’t Alter DMJ. Bullock, UC Irvine
Summary of the <strong>Too</strong> <strong>Big</strong> To <strong>Fail</strong> problem:Boylan-Kolchin, JSB, Kaplinghat 2012Expect 5-40subhalos withVmax >25 km/s(from 44 simulations)Garrison-Kimmel et al. in prepJ. Bullock, UC Irvine
Summary of the <strong>Too</strong> <strong>Big</strong> To <strong>Fail</strong> problem:Boylan-Kolchin, JSB, Kaplinghat 2012Why nothing here?Expect 5-40subhalos withVmax >25 km/s(from 44 simulations)Garrison-Kimmel et al. in prepJ. Bullock, UC Irvine
Basic Energy Argument Against SN FeedbackM ? ⇠ 10 6 MM DM ⇠ 5 ⇥ 10 7 MMust remove ~50 times m<strong>or</strong>e dark matter than mass in stars!Energy Required:> 10 55 ergsExceeds every supernovae that has gone offcoupled directly <strong>to</strong> the dark matter.Penarrubia et al. 2012;Garrison-Kimmel et al. 2013J. Bullock, UC Irvine
Numerical Experiment?Consider a M* ~10 6 Msundwarf galaxyWhat does it take <strong>to</strong>remove enough DM?J. Bullock, UC Irvine
Numerical ExperimentLive DM Halomdm = 8000 Msunε = 10pc (spline = 14pc)Dwarf galaxy potentialw/ variable mass dialstuck in the middle.(Mimics episodes of starf<strong>or</strong>mation & feedback)Garrison-Kimmel et al. 2013aJ. Bullock, UC Irvine
What does it take <strong>to</strong> solve the problem?M* ~10 6 Msun GalaxyJ. Bullock, UC IrvineGarrison-Kimmel et al. 2013a
What does it take <strong>to</strong> solve the problem?M* ~10 6 Msun Galaxy10 blow-outs of 10 7 Msun1 blow-out of 10 8 MsunJ. Bullock, UC IrvineGarrison-Kimmel et al. 2013a
What What does it does take it <strong>to</strong> take evacuate <strong>to</strong> solve the the c<strong>or</strong>e problem? of DM halo?M* ~10 6 Msun Galaxy10 blow-outs of 10 7 Msun10 blow-outs of 10 8 Msun1 blow-out of 10 9 MsunJ. Bullock, UC IrvineGarrison-Kimmel et al. 2013a
Expect:0.01 Supernova persolar mass of stars.# of SN w<strong>or</strong>th of energy Garrison-Kimmel et al. 2013aJ. Bullock, UC Irvine Energy Required
Expect:0.01 Supernova persolar mass of stars.Req. m<strong>or</strong>e energythan sum of allsupernovae in thisgalaxy!# of SN w<strong>or</strong>th of energyGarrison-Kimmel et al. 2013aJ. Bullock, UC Irvine Energy Required
Expect:0.01 Supernova persolar mass of stars.Req. m<strong>or</strong>e energythan sum of allsupernovae in thisgalaxy!Slightly m<strong>or</strong>e energyinput unbinds thehalo all <strong>to</strong>gether(fine-tuningproblem)# of SN w<strong>or</strong>th of energyGarrison-Kimmel et al. 2013aJ. Bullock, UC Irvine Energy Required
Cosmological Dwarf Halo: Vmax=35 km/sJose Oñ<strong>or</strong>bemdm = 1200MsunUse “P-GADGET” SPH- Overcomes most standard SPH issues- Hopkins, Quartaert, and Murray (2012)Oñ<strong>or</strong>be et al. (in prep)mgas = 250Msunε dm = 40pc- Self-consistent ISM.- Hydro never turned off.- Fine-structure cooling <strong>to</strong> ~100K- SNe (II & Ia), Radiation pressurefrom stellar winds, Pho<strong>to</strong>ionization(HII Regions)- Stellar feedback inputs (energy,momentum, metal fluxes) directlyfrom stellar pop modelsJ. Bullock, UC Irvine
Oñ<strong>or</strong>be et al. (in prep)Minimal change in DM densityJose Oñ<strong>or</strong>be<strong>Dark</strong> <strong>Matter</strong> OnlyFull HydrodynamicsM* ~ 10 6 MsunNot convergednumericallymdm = 1200Msunmgas = 250Msunε dm = 40pcZ=0 Stats:Abundance Matching [GOOD]Fe/H ~ -2.5 [GOOD]Mgas/M* ~ 0.1 [OK]J. Bullock, UC Irvine
<strong>Baryon</strong>ic Feedback: Not so effective f<strong>or</strong> M* < 10 7Log slope density profileCOREDataCDM-onlypredictionSimulationswith feedbackCUSPGoverna<strong>to</strong> et al. 2012J. Bullock, UC Irvine
<strong>Baryon</strong>ic Feedback: Not so effective f<strong>or</strong> M* < 10 7CORELog slope density profileM*< 10 7 Msun:very littlechange in DMpredictionDataCDM-onlypredictionSimulationswith feedbackCUSPGoverna<strong>to</strong> et al. 2012J. Bullock, UC Irvine
Is there a baryonic solution <strong>to</strong> <strong>Too</strong> <strong>Big</strong> <strong>to</strong> <strong>Fail</strong>?SN Feedback alone: NoWhy nothing here?- Not Enough Energy: hard <strong>to</strong> affectdensities with < 10 6 Msun of stars (
What’s next?Extend these studies <strong>to</strong> the field (no ram-pressure <strong>or</strong> tides)Ferrero, Abadi,Navarro, Sales, &Gurovich 2012- Examine rotation curves of fielddwarfs with Mgal~10 6-7 Msun- Same problem: not dense enough- Hard <strong>to</strong> reconcile with DM halomass function + observed lumfunctionAbstract:.... Resolving this challenge seems <strong>to</strong>require new insights in<strong>to</strong> dwarf galaxyf<strong>or</strong>mation, <strong>or</strong> perhaps a radicalrevision of the prevailing paradigm.
Beyond Cold <strong>Dark</strong> <strong>Matter</strong>?Warm <strong>Dark</strong> <strong>Matter</strong>:Self-interacting <strong>Dark</strong> <strong>Matter</strong>:CDM WDMCDM SIDMLovell et al. 2011 Vogelsberger et al. 2011m dm ⇠ keV/m dm ⇠ 1cm 2 /gLovell et al. 2011 Vogelsberger et al. 2011, 2012;Rocha et al. 2012; Peter et al. 2012;Spergel & Steinhardt (2000)J. Bullock, UC Irvine
Simula3ng Self-‐interac3ng DMScattering rate:=⇢ dm⇣m⌘v rmsF<strong>or</strong> now: Elastic, Velocity Independent, IsotropicInteresting things happen when⇠ H 0F<strong>or</strong> discussion of our methodsee talk by Miguel RochaP ij =⇣ ⌘M p v ij g ij tm
Iden3cal large-‐scale structureΛ+CDMΛ+SIDM σ/m = 1 cm 2 /g
Λ+CDMΛ+SIDM σ/m = 1 cm 2 /g
SIDM: Rounder, lower-‐density c<strong>or</strong>es. (substructure counts minimally affected)Λ+CDMΛ+SIDM σ/m = 1 cm 2 /g
DensityCold <strong>Dark</strong> <strong>Matter</strong>SIDM Makes C<strong>or</strong>ed HalosSIDM:σ/m=1cm 2 /gRocha et al. 2012radiusJ. Bullock, UC Irvine
SIDM Makes C<strong>or</strong>ed HalosDensityCold <strong>Dark</strong> <strong>Matter</strong>Velocity DispersionSIDM:σ/m=1cm 2 /gSIDM:σ/m=1cm 2 /gCold <strong>Dark</strong> <strong>Matter</strong>Rocha et al. 2012radiusradiusIsothermal velocity profile creates c<strong>or</strong>e.J. Bullock, UC Irvine
Fully cosmological zoom of isolated dwarf halo: Vmax~35km/sCDMSIDM:σ/m=0.5cm 2 /gSIDM:σ/m=1cm 2 /gSIDM makes ~ 500 pc c<strong>or</strong>eswith right density!~0.1 Msun/pc 3 (c.f. Strigari et al. 2008)Elbert et al., inpreparation.Mass resolution: 1200 Msun (DM)F<strong>or</strong>ce resolution: 40 pcJ. Bullock, UC Irvine
SIDM with σ/m=(0.5-1)cm 2 /g Solves <strong>Too</strong> <strong>Big</strong> To <strong>Fail</strong> ProblemSIDM:σ/m=0.5cm 2 /gCDMUrsMinDracoLeo ISIDM:σ/m=1cm 2 /gElbert et al., inpreparation.J. Bullock, UC Irvine
CDMPhenomenology of SIDM vs. WDMSIDMWDMRocha et al., in prep.
<strong>Dark</strong> <strong>Matter</strong> Phenomenology in the Milky Way HaloCDMRocha et al.SIDM σ/m=1cm 2 /gWDM:- Many fewer subhalosWDM m s = 6 KeV(m thermal = 1.3 KeV)<strong>Too</strong> big<strong>to</strong> failSIDM:- Roughly same number of subhalos- Solves <strong>Too</strong> <strong>Big</strong> To <strong>Fail</strong> by creating c<strong>or</strong>esin all halosCDMSIDMWDMJ. Bullock, UC Irvine
<strong>Dark</strong> <strong>Matter</strong> Phenomenology in the Milky Way HaloCDM Rocha et al.# of MW satellites > 20WDM m s = 6 KeVWDM:- Solves <strong>Too</strong> <strong>Big</strong> To <strong>Fail</strong> by removingoffending subhalos all <strong>to</strong>gether.Problem:- F<strong>or</strong> models that solve the TBTF: notenough subhalos <strong>to</strong> explain known satellitecount- Same models also struggle <strong>to</strong> explainLy-alpha f<strong>or</strong>est clumpingCDMSIDMWDMJ. Bullock, UC Irvine
<strong>Dark</strong> <strong>Matter</strong> Phenomenology in the Milky Way HaloCDMRocha et al.CDM WDM6WDM m s = 6 KeVSIDM Creates real, observable c<strong>or</strong>es in galaxies.WDM does not.CDMSIDMWDMJ. Bullock, UC Irvine
1. The <strong>Too</strong> <strong>Big</strong> <strong>to</strong> <strong>Fail</strong> ProblemTake-AwaysSatellites of MW have lower dark matter densities than expected.- Where are the most massive/dense subhalos?2. Possible solutions- SN Feedback? Not enough stars <strong>to</strong> do it.- Any <strong>Baryon</strong>ic process? Could be environmental- tides from disk/ram-pressure stripping; test w/ obs of isolated dwarfs- <strong>Dark</strong> <strong>Matter</strong> physics?- WDM: struggles w/ satellite counts, ly-a f<strong>or</strong>est, reionization. No big c<strong>or</strong>es.-‐ SIDM with σ/m ~ 0.5-‐1 cm 2 /g can do it. (This cross sec3on appears consistent w/ Bullet Cluster, cluster shapes, galaxy densi3es, but tests are ongoing. See W. Dawson / A. Peter talks.)
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