The Dark Energy Science Collaboration Andy Connolly (DESC Computing Coordinator), Rachel Bean (DESC Spokesperson)

Andy Connolly/Rachel Bean, June 2016 Science to test  and beyond Origins of cosmic acceleration could come from varied modifications to Einstein’s equations LSST, DESI, Euclid, WFIRST, CMB-S4 others designed to test these using both spatial and time-domain data through revealing different facets both individually and in combination Dark Energy evolving with z? Dark sector interactions? Anisotropic clustering? Deviations from GR? 

Andy Connolly/Rachel Bean, June 2016 Observational Probes ProbePhysical Measurement Effect of dark energy Weak Gravitational Lensing Correlated distortions in galaxy shapes Geometric distance Project growth of structure Large Scale Structure Galaxy power spectrum Geometry/ distance-redshift (z) relation: BAO Standard Ruler Structure growth with redshift (clustering & peculiar motion) Galaxy ClustersCluster abundance as function of mass and redshift Structure growth with redshift (clustering & peculiar motion) Type 1a SupernovaeFluxes and redshift Geometry/ distance-z relation: luminosity distance standard candle Strong LensingTime Delays of Multiply Lensed Sources Geometry/ distance-z relation

Andy Connolly/Rachel Bean, June 2016 LSST Dark Energy Science Collaboration (DESC) Formed in June 2012 to bring together scientists to prepare for and carry out cosmological analyses with LSST data DESC whitepaper arXiv: set out initial goals HEP style structure with democratic, member-based governance Members with astrophysics and particle physics backgrounds Expertise in instrumentation, computing, observing & theory Rapidly evolved since inception to become active international collaboration Over 490 members, 156 “full members” DOE is the lead agency: Six DOE Labs, 1/3 of full members, playing key roles. ~20 DOE HEP supported university members Public website: Full member locations

Andy Connolly/Rachel Bean, June 2016 Collaboration Structure

Andy Connolly/Rachel Bean, June 2016 DESC work organized in 12 Working Groups

Andy Connolly/Rachel Bean, June 2016 DESC Planning: 2015 DESC Science Roadmap (SRM) Find at Lays out essential tasks across the working groups to be ready for LSST commissioning Focused on tasks to build and rigorously test the analysis pipeline to ensure meets requirements to analyze LSST-level data 3 sequential Data Challenges (DC1-3) of increasing complexity & integration DC3: End-to-end analyses at LSST data complexity for all science areas

Andy Connolly/Rachel Bean, June 2016 DESC Planning: 2015 DESC Science Roadmap (SRM) Lays out WG key projects, deliverables and individual tasks to meet them

Andy Connolly/Rachel Bean, June 2016 DESC Operations Well-planned research and operations effort crucial to enable delivery of the dark energy science Ensure DOE ROI on camera investment. DESC has been working with the DOE over the last year, or more, to put in place a coherent operations plan and governance structure, to facilitate operations support, through commissioning. SLAC serves as the DOE Host Lab. Operations support will be located at DOE Labs and DESC university groups. Operations resources include: Computing infrastructure personnel Pipeline support personnel Computing hardware Collaboration infrastructure (communications/leadership support) Operations management and administration

Andy Connolly/Rachel Bean, June 2016 How do I join and get involved? If your institute/country is a member: Applications for membership are online and are dealt with on a rolling basis Members have access to DESC communication tools, internal website, and documents Full members have access to DESC computing resources and all DESC data products. Full membership requires a description of the work you plan to undertake and a commitment of time to the collaboration Tools available include: mailing lists, a confluence wiki, a Github organization (hosting code and some documents)confluence wikia Github organization Bi-annual collaboration meetings (including a dark energy school, hack days, working group meetings). Next meeting: Oxford July If your institute/country is not a member: Ask your institute to join!

Andy Connolly/Rachel Bean, June 2016 A single analysis/survey can’t give the full picture Trade offs/complementarity in Probes (SN1a, BAO, RSD, WL, Clusters + lensing, motions, positions) Photometric speed vs. spectroscopic precision Survey area vs depth - repeat imaging, dithering, cadence and overlap. Astrophysical tracers used (LRGs, ELGs, Lya/QSOs, clusters) Epochs, scales and environs being studied (cluster vs dwarf galaxies) Complementarity sensitivity to systematic errors Atmospheric contamination Chromatic PSF effects Cross-correlation science Weak lensing + spectroscopic galaxy clustering => gravitational slip CMB +LSS cross-correlations => mitigates lensing bias/contamination and yields additional cosmological science

Andy Connolly/Rachel Bean, June 2016 (based on publicly available data) LSST one of a number of upcoming surveys: Different strengths & systematics Starts, duration WFIRST ~2025, 5-6 yr Photometric galaxies (per sq arcmin) 68, in 3 bands into near IR Sample ELGs: z =1-2 (20m), 2–3 (2m) Diameter (m)2.4FoV (deg 2 )0.281 Area (deg 2 )2,400 (S) Euclid 2020 Q2, 6.25yr ~30-35, in one broad optical + IR band ELGs: z~ (~20m) ,000 (N + S) Stage IVDESILSST ~2018, 5 yr2022, 10yr ~30 over 6 bands (ugrizy) LRGs+ELGs z~ (20-30m), QSOs/Lya 1.9<z<4 (1m) Spectroscopic Survey Grism R= mm Grism R= mm Fibers R=3-4000) nm 4 (less 1.8+) ,000 (N)20,000 (S) SN1a 2700 SN1a z = 0.1–1.7 IFU spectroscopy SN1a/yr z = 0.–0.7 photometric

Andy Connolly/Rachel Bean, June 2016 To conclude LSST is a Stage IV survey with first light scheduled for early 2020 It will use multiple probes to discern the properties of dark energy and gravity on cosmic scales Varied probes promise to provide rich insights into cosmology through their complementary sensitivity to the fundamental physics & systematics In combination, LSST, DESI and CMB-S4 will provide unprecedented insights into dark energy, dark matter, the neutrino mass and inflation LSST DESC is actively preparing for the cosmological analysis of LSST data A concerted, collaborative effort is underway now, prior to commissioning, to ensure we realize the scientific potential that LSST data will provide and in a timely fashion We welcome interested members of the LSST community, please join us!