Evolution of Massive Haloes in non-Gaussian Scenarios

We have performed high-resolution cosmological N-body simulations of a concordance LCDM model to study the evolution of virialized, dark matter haloes in the presence of primordial non-Gaussianity. Following a standard procedure, departures from Gaussianit

Mon.Not.R.Astron.Soc.000,(2007)Printed1February2008

A(MNLTEXstyle lev2.2)

EvolutionofMassiveHaloesinnon-GaussianScenarios

M.Grossi1,2,K.Dolag1,E.Branchini3,S.Matarrese4,5,L.Moscardini2,6

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arXiv:0707.2516v1 [astro-ph] 17 Jul 2007

3456

Max-PlanckInstitutfuerAstrophysik,Karl-SchwarzschildStrasse1,D-85748Garching,Germany(margot,kdolag@mpa-garching.mpg.de)

DipartimentodiAstronomia,Universit`adiBologna,viaRanzani1,I-40127Bologna,Italy(lauro.moscardini@unibo.it)DipartimentodiFisica,Universit`adiRomaTRE,viadellaVascaNavale84,I-00146,Roma,Italy(branchin@ s.uniroma3.it)DipartimentodiFisica,Universit`adiPadova,viaMarzolo8,I-35131,Padova,Italy(sabino.matarrese@pd.infn.it)INFN,SezionediPadova,viaMarzolo8,I-35131,Padova,Italy

INFN,SezionediBologna,vialeBertiPichat6/2,I-40127Bologna,Italy

Accepted???.Received???;inoriginalformJuly2007

ABSTRACT

Wehaveperformedhigh-resolutioncosmologicalN-bodysimulationsofaconcordanceΛCDMmodeltostudytheevolutionofvirialized,darkmatterhaloesinthepresenceofpri-mordialnon-Gaussianity.Followingastandardprocedure,departuresfromGaussianityaremodeledthroughaquadraticGaussiantermintheprimordialgravitationalpotential,charac-terizedbyadimensionlessnon-linearitystrengthparameterfNL.We ndthatthehalomassfunctionanditsredshiftevolutioncloselyfollowtheanalyticpredictionsofetal.Theexistenceofpreciseanalyticpredictionsmakestheobservationofrare,massiveobjectsatlargeredshiftanevenmoreattractivetesttodetectprimordialnon-Gaussianfeaturesinthelargescalestructureoftheuniverse.

Keywords:earlyuniverse–cosmology:theory–galaxies:clusters–large-scaleoftheUniverse

1INTRODUCTION

In ationisconsideredthedominantparadigmforunderstand-ingtheinitialconditionsforstructureformationintheUniverse.Asaconsequenceoftheassumed atnessofthein atonpo-tential,anyintrinsicnon-linear(hencenon-Gaussian,NG)effectduringstandardsingle- eldslow-rollin ationisgenerallysmall.Thus,adiabaticperturbationsoriginatedbythequantum uctu-ationsofthein aton eldduringstandardin ationarenearlyGaussiandistributed.Despitethesimplicityofthein ationaryparadigm,however,themechanismbywhichperturbationsaregeneratedisnotyetfullyestablishedandvariousalternativestothestandardscenariohavebeenconsidered.Akey-pointisthattheprimordialNGismodel-dependent.Whilestandardsingle- eldmodelsofslow-rollin ationleadtosmalldeparturesfromGaussianity,non-standardscenariosforthegenerationofprimor-dialperturbationsinsingle- eldormulti- eldin ationallowforalargerlevelofnon-Gaussianity(see,e.g.Bartoloetal.Bernardeau&Uzan2002;Chenetal.2007).Moreover,alternativescenariosforthegenerationofthecosmologicalperturbationslikethecurvaton(Lythetal.2003;Bartoloetal.2004),theinhomoge-neousreheating(Kofman2003;2004)andtheDirac-Born-Infeld(DBI)-in ation(Alishahihaetal.2004)scenarios,arecharacterizedbyapotentiallylargeNGlevel(seeforareviewBartoloetal.Becauseitdirectlyprobestheprimordialperturbation eld,theCosmicMicrowaveBackground(CMB)temperatureanisotropyandpolarizationpatternhasbeenconsideredthepref-

erentialwayfordetecting,orconstraining,primordialNGsignals,therebysheddinglightonthephysicalmechanismsforperturbationgeneration.

Alternatively,onecanconsidertheLarge-ScaleStructure(LSS)oftheUniverse.Thisapproachhasbothadvantagesanddis-advantages.UnliketheCMB,whichreferstoa2Ddataset,LSScarriesinformationonthe3Dprimordial uctuation elds.Ontheotherhand,thelatenon-linearevolutionintroducesNGfea-turesonitsown,thatneedtobedisentangledfromtheprimor-dialones.Thiscanbedoneintwodifferentways:observingthehigh-redshiftuniverse,suchase.g.anisotropiesinthe21cmback-ground(Pillepichetal.2007,seealsoCoorayorstudyingthestatisticsofrareevents,suchasmassiveclusters,whicharesen-sitivetothetailsofthedistributionofprimordial uctuations.Sofar,theinvestigationoftheeffectsofNGmodelsintheLSShasbeencarriedoutprimarilybyanalyticmeans(Lucchin&Koyamaetal.Matarreseetal.Robinsonetal.Robinson&et2000,2001;Komatsuetal.2003;Scoccimarroetal.2004;Amara&RefregierRibeiroetal.Sefusattietal.Sefusatti&Komatsu2007;Sadehetal.N-bodysimulationswithNGinitialconditionswereperformedintheearlyninetiesetal.1990;Moscardinietal.1991;Weinberg&Cole1992),buttheconsideredNGmodelswererathersimplistic,beingbasedonfairlyarbitrarydistributionsfortheprimordialdensity uctuations(seealsoMathiset2004).Onlyveryrecently,Kangetal.haveinvestigatedmorerealisticNGmodels.