CosmicVisions:DarkEnergyIntroduction

CosmicSurveysStatusandReport

NextSteps

KlausHonscheidOhioStateUniversityHEPAP,Dec2,2016

CosmicVisions–DarkEnergyCosmicVisionsDarkEnergygroup:

EstablishedbyDOEOHEPinAugust2015asa2-waycommunicationgroupwiththeHEPcommunity:ScottDodelson(Chair),Katrin Heitmann,ChrisHirata,KlausHonscheid,AaronRoodman,Uros Seljak,Anze Slosar,MarkTrodden.

Whatwillcomplement,buildon,andextendbeyondthecurrentlyplannedHEPDarkEnergyexperiments.

2otherCVgroups(CMBandDarkMatter)coordinatewithDOECMBisinadifferentphaseTheCMB-S4community-basedcollaborationreleaseafirstversionoftheirScienceBook

Wearenowstartingalongthesameprocess:buildingbroadcommunitysupportanddevelopingstrongsciencecase)1-2yearsawayfromaDE++ScienceBook(goodtimingfornextSnowmass/P5andDecadalSurvey)

FutureCosmicSurveysStudiesNAS’s“AStrategytoOptimizetheU.S.OpticalandInfraredSystemintheEraofLSST”(Elmegreen report)ReportonKavli FuturesSymposium(NOAO,LSST):“MaximizingScienceintheEraofLSST:AcommunityBasedStudyofNeededU.S.OIRCapabilities”

Process– Weeklytelecons betweenAugust2015andJanuary2016– AttendedDESIandLSSTDESCCollaborationMeetings– Organizedthreeworkshopsheldtogatherinputforthethreewhitepapers:

– Brookhaven,October1,2015.Agendaandslidesavailableathttps://indico.bnl.gov/categoryDisplay.py?categId=124

– Fermilab,November10,2015.Agendaandslidesavailableathttps://indico.fnal.gov/conferenceOtherViews.py?view=standard\&confId=10639

– SLAC,November13,2015.Agendaandslidesavaiable athttps://indico.fnal.gov/conferenceDisplay.py?confId=10842

• Face-to-FacemeetingatFermilab inJanuary2016– ThreewhitepaperssubmittedtoDOE– TwopapersweresubmittedtothearXiv:1604.07626 and1604.07821

(A) Theroadmapforcosmicsurveysiswelldefined.SinceSnowmass:LSST,DESI,WFIRSTapproved*

Anewprojectcannotbeincremental

2 Dark Energy 5

BOSS$

2029$2027$2025$2023$2021$2017$2015$2013$ 2019$

Dark$Energy$Experiments:$2013$9$2031$

Dark$Energy$Survey$(DES)$

Extended$BOSS$(eBOSS)$

HSC$imaging$ PFS$spectroscopy$

Dark$Energy$Spec.$Instrument$(DESI)$

Large$SynopHc$Survey$Telescope$(LSST)$

BOSS$

HETDEX$

2031$

Blue$=$imaging$Red$=$spectroscopy$

Stage$III$

Stage$IV$

Euclid$

WFIRST9AFTA$

Figure 1. A timeline of Stage III and Stage IV dark energy experiments – photometric and spectroscopic– in which US scientists are playing an important or leading role. Most of the projects are ground-based witheither US leadership (BOSS, DES, HETDEX, eBOSS, DESI, LSST) or active participation (HSC, PFS).The two space missions are Euclid, led by the ESA with a NASA-sponsored team of US participants, andWFIRST, led by NASA.

of spectroscopic redshift measurements can enhance the dark energy constraints from LSST compared toits baseline capabilities [12]. Finally, new instrumental capabilities – e.g., methods that suppress flux fromemission lines from the night sky, which are much brighter than distant galaxies at infrared wavelengths,or new detector technologies that would measure photon energy rather than just quantity – could enablepowerful new dark energy experiments to be conducted at reduced costs. Modest investments in theseavenues may yield large potential payo↵s in the future.

The following sub-sections summarize the physical probes and measurements that speak to dark energyscience. Each of these approaches is detailed further in a separate document [13, 14, 11, 15]. Taken together,these measurements and the projects that enable them constitute an all-out attack on the problem of cosmicacceleration. The program planned over the coming decade guarantees continuing US leadership in this field.

2.1 Distances

The relationship between the redshift and distance of an object is one of the primary tests of the expansionhistory of the Universe, and therefore played a key role in the discovery of the accelerating Universe. Thesimple graph of the distance scale of the Universe as a function of redshift, indicating the evidence forcosmic acceleration, has become an iconic plot in the physical sciences. The data for this plot so farcome from measurements of Type Ia supernovae and baryon acoustic oscillations (BAO) and these willbe the sources of streams of data in coming years. DES and LSST will provide an essentially limitlesssupply of supernova, thousands, then hundreds of thousands. The DES collaboration and LSST-DESCwill coordinate the spectroscopic classification of a fraction of these objects. The challenge is to makemeasurements thoroughly enough to mitigate systematic problems, especially those that depend on redshift.Detailed studies of nearby supernovae are beginning to provide clues for how to do this. Much would be

Community Planning Study: Snowmass 2013

Findings

GreatSynergies

DESWLmassmap Massmap(κ)inferredfromdistortionsinCMB

GalaxySurveysandCMB GalaxySurveysandGammaRays6

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Figure 2. Binned �-ray counts maps (E > 1 GeV) for 10� ⇥ 10� ROIs centered on 15 targets that were not analyzed by Drlica-Wagneret al. (2015a) or Ackermann et al. (2015b). The dSph candidates are indicated with white “⇥” symbols, while 3FGL sources in the ROIare indicated with white “+” symbols. The counts maps are binned in 0.�1 ⇥ 0.�1 spatial pixels and smoothed with a 0.�25 Gaussian kernel.

Figure 3. Bin-by-bin integrated energy-flux upper limits at 95% confidence level assuming a point-like model for the 15 targets inFigure 2. The median expected sensitivity is shown by the dashed black line while the 68% and 95% containment regions are indicated bythe green and yellow bands, respectively. The expected sensitivity and containment regions are derived from 300 Monte Carlo simulationsof the �-ray background in the regions surrounding each respective target.

DarkMatterMass[GeV]

GammaRaysfromDESDwarfGalaxies

AnalogywithParticlePhysicsParticle Physics Survey Cosmology

New physics discovery relies on:

• increasing energy of collisions, • Allows access to new eventsthat don’t appear at lower E.

• increasing accelerator luminosity• e.g. produce more Higgs, and measure decay modes more accurately.

• Can allow very rare decays to be discovered at statistically significant level.

New physics discovery relies on:

• increasing redshift of detection,• Allows access to new eventsand objects absent at lower z.

• increasing number of objects• detecting more objects, allowsmore precise measurements ofinhomogeneities.

• Can allow different signatures inshape of power spectrum to bediscovered at statistically significant level.

All allow access to a lot of new physics!SlidebyMarkTrodden

(B)EvenafterDESIandLSST,therewillbealotofinformationleftinthesky

1604.07626Findings

NotjustDarkEnergy

Broadrangeofimprovementsfromguaranteedtosearches

(C)InstrumentationR&Dandnewtechnologieswillbekeyformany(all)futurecosmicsurveys

CVWhitepaperonarXiv 1604.07821

GeCCDs(MITLL,LBNL)

C.Leitz

MicroShutterArraysdevelopedforJWST

MKIDSDetectorArraysFindings

DESI-2

21cm

(D)Therearemultipleideasforfutureprojectsthatcanminethatinformation

Findings

SouthernSpectroscopicSurveyInitiative(SSSI)

LowResolutionSpectroscopyakaHi-ResPhotometry

BillionObjectApparatus

Theory,SyntheticSkyMaps&SimulationsReliablepredictionsofobservablesonsmallScales;viablefundamentalphysicsmodels,modelingeffortstomatchtheexpectedstatisticalpowerofLSSTandDESI;End-to-endsimulationsandsyntheticcatalogsforvalidationofpipelinesandsystematics

Manyadditionalideas,variationsandmore

KinematicWL(E.Huff):Getshapepriorsbymeasuringrotationcurves

NovelProbes(StudyModifiedGravity)Comparethebehaviorofgravityinscreenedandunscreenedregions(e.g.infall velocitiesofnearbygalaxies)

PixelLevelComparisonCombinedatasamplesatthepixellevelacrossprojects,fundingagenciesandcontinents.

Recent Activity• CosmologyusingLow-ResolutionSpectroscopy

https://kicp-workshops.uchicago.edu/LowResCosmology2020/overview.php(35participants)

• SSSIhttps://indico.hep.anl.gov/indico/conferenceDisplay.py?ovw=True&confId=1035(40participants)

• FutureCosmicSurveyshttps://kicpworkshops.uchicago.edu/FutureSurveys/index.php(145participants)

DESI-2• DESI isa5000-fiber,8deg2 FOVspectroscopicinstrumentwithR=2000

(350nm)-5500(980nm),tobeinstalledontheMayall @Kitt Peak.Willdoa14sq.deg surveyof35Mgalaxies&quasars+10Mstarsfrom2019-2024

• DESI-2: sciencewithDESIaftertheplannedsurveyiscomplete(2025+).Operatingcostsestimatedat7-8Mperyear.– DESIasiswillstillbeaworldleadinginstrumentin2025,canobserveroughly

20Mspectraperyear.– ModestupgradestoDESIcouldextendthespectrographintheredandenable

anefficienthigherredshiftsurvey• Possiblesurveys/sciencedrivers:

– Denselowredshiftsurvey(e.g.magnitudelimitedto21.5)allowsprecisepowerspectrum,density&velocityfield,withbroadscienceapplicationsingalaxyformationandcosmologyincludingtestsofmodifiedgravity

– Highredshiftsurveyatz>1.5wouldprovidenewinformationinthelinearregimebeyondDESI,couldbeenabledwithmodestinstrumentupgradesorimprovedselection

– Significantoverlapandcross-correlationsciencewithLSSTandCMB-S4– Targetedsurveys,e.g.gravitationalwavefollow-up,stellarstreams,dense

samplingofclusterorlensfields,etc.

High-ResPhotometry

MKIDS(energysensitive)R~100achievable?

PAUCam

SouthernSpectroscopicSurveyInstrument• SSSIwouldbeamassivelymultiplexed(>2500x),wide-field(goal:

>1deg2)optical/IRspectrographona6.5+mtelescope• SSSIprovidesspectroscopiccapabilitiesmatchedtoLSSTand

CMB-S4surveyareasanddepths;Southernsitepreferable• SSSItakesfulladvantageofcurrenttechnologiesandDESIlegacy• Widevarietyofsciencecases;e.g.:reduceLSSTphoto-zerrorsby

afactorof2viatrainingspectroscopy• AtoppriorityfromKavli/NOAO/LSSTandinternational

prioritizationsaswellasCosmicVisions:manypotentialpartners

BillionObjectApparatus• Concept: optical/IRspectrographona10mtelescope

– massivelymultiplexed(50k-100kfiber)– wide-field(1-5deg2)

• PrimaryObjective:completesamplingoflineardensityfieldusingbetween500Mand1Bspectroscopictracers– Maximalprecisiononcosmologicalconstraintswithclusteringtoz<3.5

• Feasibility: sharesinstrumentdesignwithexisting/proposedexperiments– Designfor10-mclasstelescopewithlargeFOV(Pasquini etal.,2016)– SpectrographdesignforDESIadaptableto4th infraredchannel(1-1.4micron)– TestsoftargetselectionandspectroscopiccompletenesswithPFS

• Programmatics: Stageddevelopmentwithotherspectroscopicsurveys– SimilarspectrographdesigntoDESI,DESI-II– SharedplatformwithSSSI

• PartnershipwithDOElabs: R&Dtomeettechnicalchallenges– Densepackingoffibersinfocalplane– Scalespectrographproductionto100,000fibers– DevelopmentofGeCCDsatLBNL

PossibleRoadMapforSpectroscopy• Theproposedspectroscopicsurveysbuildoneachotherdirectly• DESI-2wouldberelativelylowincostandcouldfollowDESI

immediatelyin2024– SpectrographupgradestoaddIRarmwouldenhancecapabilitiesathigherredshifts

– MovingtoBlancoisanoption,increasingLSSToverlap• SSSIcouldreuseDESIspectrographstoreducecosts– Earliestpossibledeploymentc.2026– Mostefficientoptionwouldbetodeployon11-12mtelescope(e.g.MSEorEuropeanwide-fieldconcepts)

• BOAwouldrequirebotha>10mwide-fieldtelescopeandsignificanthardwareR&D– Earliestpossibledeploymentearly2030s– CouldutilizetelescopeoriginallydevelopedforSSSI

RadioCosmology:21cm/IntensityMapping• Nearterm: Forecaststailoredtov.highradialresolutionof

radiocosmology;useexistinginstrumentstouncoversystematicsandtrytoconstraint forCMB-S4neutrinos.

• Longterm: Pushingtheredshift,scale,andsensitivityfrontierswithBAOmeasurementsfrom2<z<6;matterpowerspectrumonsmallscalesatz>35.

• ContrastwiththeSKA: Proposedinstrumentswouldbetargetedcosmologyexperiments,ratherthantheSKA’sphilosophyofageneralobservatory,allowingfundamentalphysicstobeprobedatafractionofthecost.

• PartnershipswithDOElabs:– Highdatarates:DOEHEPexpertiseinhighthroughputcomputing.– Next-gencorrelator techleveragingDOEradiofrequencytech.– R&Dforreal-timeionospheric calibrationforhighestz.– LargescaleDOEmanufacturingcapabilitiesfor~106 element“dream

cosmologyinstruments”

OurNextSteps• InterestgroupsformedattheCosmicSurveysWorkshop

• Proceedtogethergeneratingprojectionsoverthenext6months-oneyear,withtelecons onceevery3months

• CVDEGroupprovidescoordination– git Organizationforcodesharing,predictioncomparisons,writing,issues,…

– Follow-upworkshopinoneyearwiththegoalofstartingtheScienceBookbythen

• TowardSnowmass202x,P5andthenextDecadalSurvey

Backup

OverlapwithCMB:Lensing