Fluctuations in models with sterile- WDM Silvio Bonometto Physics Dep., Trieste Univ. & INAF,...
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Transcript of Fluctuations in models with sterile- WDM Silvio Bonometto Physics Dep., Trieste Univ. & INAF,...
Fluctuations in modelswith sterile-WDM
Silvio BonomettoPhysics Dep., Trieste Univ. &INAF, Trieste Observatory
Conca Specchiulla, sep 10, 2014
Paper in collaboration with 3M’s
R.Mainini, A. Macciò, I.Musco
LWDM cosmologies, “spiced” with a pinch of strongly coupled CDM, meet all data LCDM fits, as well as data LCDM fails to fit
sterile mass predicted?
LCDM cosmologies meet cosmological data down to galactic scale
Problems below galactic scale:
•Milky Way satellite abundance LCDM N-body simulations yield 20 times more satellites than observed, for a galaxy of the MW size Klypin et al ApJ 522 (1999) 82, Moore et al. ApJ 524 (1999) L19
•Dwarf galaxies exhibit a core radial density not NFW in the central region Moore, Nature 370 (1994) 629, Flores & Primack, ApJ 427 (1994) L1, Diemand et al MNRAS 364 (2005) 665, Macciò et al MNRAS 378 (2007) 55, Springel et al., MNRAS 391 (2008) 1685, de Block et al., ApJ 552(2001) L23, Oh et al., AJ 141 (2011) 193
•Dwarf galaxy abundance in large voids ….
hydro sim.including baryonphysics reduce
discrepancyto factor 2-3
biggergalaxies also
found to have coreM-ind’nt size500-1000 pc
more controversial
LWDM cosmologies halos with coree.g. Macciò et al., MNRAS 428 (2013)
Core radius related toDM particle mass:To have a core around 500-1000 pcneed m = 80-110 eV
STERILE NEUTRINO with m \sim 90eV ?
a catch-22 problem:to have a dwarf galaxies with a 500-1000 pc corewe cannot have dwarf galaxies
however… cores & dwarfs do exist !!!
New class of models :LWDM spiced with a grain of DARK pepper
s-LWDM modelsnot ad-hoc
deriving from finding a newtracker solutionin coupled-DEmodels
Spiced LWDM cosmologies Summary
Background• A dual component in a stationary primeval Universe • Connecting DE with inflation
• Stationarity break and rise of present cosmic environment
Inhomogenities• Linear theory• Simulations: satellites and profiles
Problems• Early non linearity , DE-CDM decoupling
Bonometto S.A., La Vacca G., Sassi G., JCAP08 (2012) 015 Bonometto S.A. & Mainini R., JCAP03 (2013) 038 Macciò A.V., Bonometto S.A., Mainini R., Musco I. (in preparation)
Strong CDM-DE coupling allows fluctuations to persist also on dwarf galaxy and MW substructure scales
preliminary
Background metric
Quintessential DE
covariant form
Cou.DE :J.Ellis et al., PL 228B (1989) 264C.Wetterich, A&A 301 (1995) 321L.Amendola, PRD 69 (1999) 043501L.A. & Tocchi-Valentini D., PRD 66 (2002)043528…. and many many others
In FRW space
data (hopefully) to yield w(a) [sooner than V(F)]
couplingallows DE
to keep signif.density also
at high z
We shall forget the potential shape, just assumingw+1 at large z, w-1 at small z, transition at zd
resultsmildly dependent
on ad &
resultsmildly dep. on zd
scarse dep.on
classical approachesassume cou.CDM to beonly DM, then << 1
here CDM is a tiny componentmain DM is uncoupled
this allows quite large
w=+1 at large z is a generic featurefor any choice of self-inter. potential
Kinetic field would dilute as aCDM would dilute as aEnergy flow from CDM to DE makes both component to dilute as a--4
--3-6
= (mp/b) ln()
f=exp[-ln()]=1/L = ()
“…. mass redshifting”
density parametersduring radiative expansion
At high z all components sharesimilar densities (remindingsimilar decoupling redshifts)in a fully stationary expansion
Eve of the present epoch: T approaches mw
apologiesfor different color
choice
Coupling persists down to z=0 Coupling fades after invariance break
=10
WDM fluc.’ns restarted &baryon fluc.’ns enhanced bylarge ampl. cou-CDM fluc.’ns
” Cou.CDM : NO meszaros’ effect
fluc’ns in CDM continue to grow afterentering the horizon, over any scale
Creating deep “potential wells”
A possiblemodel pathology:coup’d CDM fluc.nsmay become >>1
Simplest solution:coupling shouldfade at low z
necessarily afterconformal inv. break by wdm derelativization
this preserves wdm fluc’n restoration
delay=Log[a(dec’g)/a(der’l’n)]
delay = 4decoup’gapproximativelywhen w shiftsfrom +1 to -1
delay = 2shown in the plot
after dec’gsufficient thatCDM+bar fluc’nsare linear
however : c<<b
models with non-linearCDM fluc’s could stillbe physicaljust hard to computestructure formation
early non-linearityto modify pop III predictions
2
mw/eV 96.80 48.51
g*/mw= 0.980
Simulated model
delay=4decouplingat +/- transition
very little changes for delay=2
Original simul.: Lbox=20 Mpc/h, Npa=300^3zoom grid: Npa=7200^3=3.73x10^11 Npa,halo=13.1x10^6,mpa=1500 Ms/h
Same halo: 2.07x10^10 Ms/h (within R200)CDM particles (v=0) WDM particles (thermal vel)
CDM pa. mw=95eV (thermal velocities)
Original simul.: Lbox= 90 Mpc/h, Npa=300^3zoom grid: Npa=4800^3, Npa,halo=2.4x10^6, mpa=4.57x10^5 Ms/hM_halo = 1.1x10^12 Ms/h (not a lucky halo choice)
CDM particles WDM particles only NO small halos
PRELIMINARY CONCLUSIONS FROM SIMULATIONS
s-LWDM LCDM 1:6 cold
10^10 profile forming core NFW intermediate Dwarf closer to NFWGalaxy satellites almost 0 in excess intermediate just a few
10^12 profile NFW in all casesMilky fattening blobsWay satellites massive satellites remain small ones vanish
BUT:small halocomponentproportions
?
reso-lution
....
Conclusions
• Sub-galactic scale features hard to explain by LCDM• LWDM can help: critical feature warm particle mass• LWDM with particle 80-110 eV meets rotation curves, satellites, etc.• LWDM spectrum for such mass unsuitable
• New tracker solution for cou-DE models (background)• Primeval conformal invariance• 2 DM component already widely considered in literature• here CDM coupled + WDM uncoupled, similar primeval densities• LWDM models spiced with a pinch of cold dark pepper ….• tracker solution holding since inflation• possible connection with inflationary dynamics
• linear fluctuation evolution solved • Cou-CDM does not feel Meszaros effect• CMB spectra identical to LCDM• CDM fluc’ns re-create WDM fluc’ns
• excessive amplitude of CDM fluctuations: a computational problem• however: once conformal invariance brocken, decoupling harmless
• Simulations based on s-LWDM cosmologies confirm : rotation curves, satellite problems solved• Pop III physics to be revisited: early seeds
mostly
when coupling switched on w+1 at high z for any potential
Small values of to be coherent with observational dataDE decreases when w close -1, then almost parallel to CDM
densities in the presenceof coupling
Spectral distorsionsdue toenergyflowfromDM toDEcompensatedbyspectral distorsionsdue toneutrino mass O(1ev)
La Vacca G. et al. J CAP 0904 (2009) 007 Amendola L. et al arXiv: 1111.1404 (0.180.16)
up to 0.18 consistent withdata if neutrino mass O(0.2eV)
CDM-DE coupling: a MUST if
“large” massdetected in particle
experiments (e.g.: )
C<0.4/mp
early universe:DE purely kinetic :constantlyd \sim 0.01c
at z \sim 10potential termtakes over