The quest for Dark Energy when theories meet simulations

Transcription

1 The quest for Dark Energy when theories meet simulations Gong-Bo Zhao ICG, University of Portsmouth

2 Universe is Accelerating Atoms Dark Matter Modified Gravity e.g. Chameleon, Symmetron, Dilaton, Braneworld, etc "?! Indistinguishable at the background level Need to study the structure growth to break the degeneracy

3 Make Universe accelerate by tweaking RHS Cosmological Constant (w=-1)! DARK ENERGY w=p/r<0 Quintessence (w>-1)! Phantom (w<-1)! Quintom (w crosses -1)!!!

4 Model-independent reconstruction of w Crittenden, Pogosian, GBZ (2009) Crittenden, GBZ, Pogosian, Samushia, Zhang (2012)

5 Hide w(z) models in the mock data

6 w reconstructed successfully Crittenden, GBZ, Pogosian, Samushia, Zhang(2012)

7 Result using the latest data (WMAP7+SNLS3(Union2.1)+BOSS BAO, RSD) GBZ, Robert Crittenden, Levon Pogosian, Xinmin Zhang, to appear soon

8 Make Universe accelerate by tweaking LHS MODIFIED GRAVITY chameleon, symmetron, dilaton DGP Massive gravity!!

9 Fighting against gravity: A painful happiness!! Image credit: Wayne

10 Testing GR on linear scales General Modified Relativity Gravity!!

11 Weak Lensing µ(a,k), g(a,k) cosmo. param. MGCAMB Galaxy Counts ISW!!

12 GBZ, Giannantonio, Pogosian, Silvestri, Bacon, Koyama, Nichol, Song , PRD, 2010!!

13 Song, GBZ, Bacon, Koyama, Nichol, Pogosian , PRD, 2011

14 GBZ, Li, Linder, Koyama, Bacon, Zhang , PRD, 2012!!

15 Testing GR on nonlinear scales? Simulation is needed!

16 In GR

17 In f(r) l C

18 In very dense regions l C

19 Get some sense

20 GR

21 f(r)

22 Structure formation in GR

23 Structure formation in f(r)

24 Dynamical Mass

25 Dynamical Mass

26 Dynamical Mass Spherical symmetry

27 Lensing Mass

28 Lensing Mass

29 Lensing Mass Spherical symmetry

30 Mass Difference

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32 In underdense environment

33 In underdense environment

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35 In dense environment

36 In dense environment The halos are screened so that they cannot feel the enhancement of gravity!

37 Fabian Schmidt, , PRD 2010

38 To see the pure environmental effect, we need a new environment indicator which is uncorrelated with halo mass The three-dimensional distance to the Nth nearest neighbour with a viral mass that is at least f times that of the halo under consideration, divided by the virial radius of the Nth nearest neighbour: Haas et al.,

39 Small D Affected by the local environment

40 Small D Affected by the local environment Large D Affecting the local environment

41 GR analysis, Haas et al., D is a clean indicator for the local environment!

42 f(r) analysis, GBZ, Baojiu Li, Kazuya Koyama (PRL 2011)

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44 Clean mass dependence!

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46 Large scatter shows the environmental effect!!

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48 Apparent environmental dependence!!

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50 No screening at all!!

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52 No screening!

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54 Maximum screening Core is better screened

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56 Screened purely by environment

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58 Screening on the edge shows environmental dependence!

59 Observationally Lensing Mass Dynamical Mass

60 Measure lensing and dynamical mass for each halo; Divide the sample using D; Compare!

61 Measure lensing and dynamical mass for each halo; Divide the sample using D; Compare! Applying to BOSS data

62 Screening map in the SDSS region Cabre, Vikram, GBZ, Jain, Koyama

63 RSD measurement Jennings, Baugh, Li, Zhao, Koyama see Elise s talk

64 A new GR test using the spin of halos Lee, GBZ, Li, Koyama

65 Summary and Outlook A 2s detection of w deviating from -1 GR so far so good N-body simulations for MG provide a platform for the GR tests on nonlinear scales using the upcoming data of BOSS, eboss, BigBOSS, Euclid, LSST, KDUST, TMT?