Simulating the joint Simulating the joint evolution of quasars, evolution of quasars,

galaxies and their large-galaxies and their large-scale distributionscale distribution

Springel et al., 2005Springel et al., 2005

Presented by Eve LoCastroPresented by Eve LoCastro

October 1, 2009October 1, 2009

IntroductionIntroduction Astronomers are still seeking answer(s) to how galaxies Astronomers are still seeking answer(s) to how galaxies form and explanations for large-scale distribution of form and explanations for large-scale distribution of structurestructure

Observational surveys (2dFGRS, SDSS; Hubble) have Observational surveys (2dFGRS, SDSS; Hubble) have substantially improved knowledge of nearby clustering substantially improved knowledge of nearby clustering patterns and physical properties of galaxiespatterns and physical properties of galaxies

CDM predicts hierarchical growth of structure via CDM predicts hierarchical growth of structure via gravitational instability, largely confirmed by gravitational instability, largely confirmed by observations but more rigorous confirmation requires observations but more rigorous confirmation requires detailed calculated predictions for comparisondetailed calculated predictions for comparison

The authors and members of the Virgo Consortium The authors and members of the Virgo Consortium contrived the contrived the Millennium RunMillennium Run to reproduce formation to reproduce formation and evolution of structure starting at earliest seed and evolution of structure starting at earliest seed perturbationsperturbations

OutlineOutlineNew galaxy surveys are giving new, New galaxy surveys are giving new, insights into clustering patterns and insights into clustering patterns and physical properties of galaxiesphysical properties of galaxies

Necessary to have robust prediction of CDM Necessary to have robust prediction of CDM for comparison; made difficult by non-linear for comparison; made difficult by non-linear behavior of DM at early, small scalesbehavior of DM at early, small scales

The The Millennium SimulationMillennium Simulation is the largest, is the largest, most-intricate attempt to model evolution most-intricate attempt to model evolution of dark and baryonic matter into large-scale of dark and baryonic matter into large-scale structurestructure

The Millennium RunThe Millennium Run Completed 2004 after Completed 2004 after a month of processinga month of processing

NN-body simulation -body simulation evolved 2160evolved 216033 particles particles of baryonic and dark of baryonic and dark matter from z=126 matter from z=126 through present epochthrough present epoch

Cubic region Cubic region measuring 500measuring 500hh-1-1Mpc Mpc per side; mass approx per side; mass approx by 10by 1088MM~~ particles particles

Periodic boundary Periodic boundary conditionsconditions

Image credit: the Virgo Consortium

Dark Matter: Halo HistoryDark Matter: Halo HistoryResults of this and prior simulations show dark Results of this and prior simulations show dark matter with complex filamentary structure, matter with complex filamentary structure, stretching in all directions through spacestretching in all directions through space

Exceptionally-concentrated nodes of dark Exceptionally-concentrated nodes of dark matter contain many halos that have matter contain many halos that have gravitationally accumulated over timegravitationally accumulated over time

The formation of structure is detailed by The formation of structure is detailed by merger-tree history of objectsmerger-tree history of objects Image credit: the Virgo

Consortium

Dark Matter Halos & Dark Matter Halos & GalaxiesGalaxies

From Springel et al., 2005

Snapshots of differential Snapshots of differential halo number density by halo number density by massmass

Weighted by Weighted by ρρ, mean , mean density of universe (density of universe (ρρ was greater at earlier was greater at earlier times)times)

Dotted linesDotted lines are are Press-Press-Schecter predictions at Schecter predictions at zz=10.07 and =10.07 and zz=0=0

The Earliest QuasarsThe Earliest Quasars

Image credit: the Virgo Consortium

Furthest quasars lie near Furthest quasars lie near zz=6.43, housing =6.43, housing extremely massive black holes (~10extremely massive black holes (~1066 M M~~))

Such early, massive bodies extremely rare Such early, massive bodies extremely rare co-moving density 2.20{co-moving density 2.20{++.73}x10.73}x10-9-9 hh33MpcMpc-3-3

Should be ~<1 in volume of M.S.Should be ~<1 in volume of M.S.

Fate of the quasars?Fate of the quasars?Three methods of combing through results Three methods of combing through results to classify massive objects: halo mass, to classify massive objects: halo mass, stellar mass, or instantaneous S.F.stellar mass, or instantaneous S.F.

Environment of quasar candidate: sits on Environment of quasar candidate: sits on highly prominent dark matter filament highly prominent dark matter filament flanked by a large number of smaller, flanked by a large number of smaller, fainter “galaxies”fainter “galaxies”

M.S. data, can trace the evolution of quasar M.S. data, can trace the evolution of quasar from earliest progenitor at from earliest progenitor at zz=16.7, one of =16.7, one of only 18 collapsed objects in entire volumeonly 18 collapsed objects in entire volume

Simulating into future, quasars become Simulating into future, quasars become central objects in massive galaxy clusterscentral objects in massive galaxy clusters

Clustering evolution of dark Clustering evolution of dark matter & galaxiesmatter & galaxies

Large volume and mass content of M.S. allows Large volume and mass content of M.S. allows significant statistical calculations on clustering significant statistical calculations on clustering of galaxies, i.e. a 2-point correlation functionof galaxies, i.e. a 2-point correlation function

Galaxy clustering in simulation reproduces Galaxy clustering in simulation reproduces dependence of slope on magnitude and color, dependence of slope on magnitude and color, but a difference in amplitude—unaccounted but a difference in amplitude—unaccounted physics process?physics process?

Modes of dark matter power spectrum grow Modes of dark matter power spectrum grow linearly at earliest times; nonlinear evolution linearly at earliest times; nonlinear evolution first affects smallest scalesfirst affects smallest scales

Galaxy clusteringGalaxy clustering

From Springel et al., 2005

““Wiggle” RoomWiggle” Room

Evolution of the power Evolution of the power spectrum from sim start, spectrum from sim start, divided out by CDM divided out by CDM spectrum to leave spectrum to leave signature ripplessignature ripples

Black curve traces same Black curve traces same initial conditions for initial conditions for comparison as structure comparison as structure developsdevelops

Red is dark matterRed is dark matter

Green is galaxiesGreen is galaxies

From Springel et al., 2005

ConclusionsConclusionsDark matter:Dark matter:

Predicts hierarchical growth of structurePredicts hierarchical growth of structure

Results of M.S. disagree with Press-Schecter by Results of M.S. disagree with Press-Schecter by order of magnitude, agree with obs. surveysorder of magnitude, agree with obs. surveys

Quasars:Quasars:

FFormed at locations of earliest collapsed objects; ormed at locations of earliest collapsed objects; now believed to be enjoying retirement at centers now believed to be enjoying retirement at centers of massive clustersof massive clusters

Large Scale StructureLarge Scale Structure Baryon acoustic oscillations of CMB should be Baryon acoustic oscillations of CMB should be

detectable in power spectra of galaxy distribution detectable in power spectra of galaxy distribution at z<3 and low-z NL dark matter power spectrumat z<3 and low-z NL dark matter power spectrum

Will put constraints on dark energyWill put constraints on dark energy