Gravita'onal Waves on the Horizon

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Osborne Foster
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1 Gravita'onal Waves on the Horizon Scien'fic Case for CMBPol The Horizon A Calcula'on Scott Dodelson Primordial Gravitational Waves August 27, 2009

Foreground Science Knowledge and Prospects. arxiv: 0811.3920 3. Probing Infla9on with CMB Polariza9on. arxiv:0811.3919 4.

2 Scien'fic Case for CMBPol 1. The Origin of the Universe as Revealed Through the Polariza9on of the Cosmic Microwave Background. arxiv: Foreground Science Knowledge and Prospects. arxiv: Probing Infla9on with CMB Polariza9on. arxiv: Reioniza9on Science with the Cosmic Microwave Background. arxiv: Gravita9onal Lensing. arxiv: Prospects for polarized foreground removal. arxiv: A Mission to Map our Origins. arxiv:

3 How can we detect Primordial Gravita'onal Waves? Backer, Jaffe, Lommen 2003 Primordial Signal

4 Polariza'on field decomposed into E/B modes Density perturba'ons produce only E modes

5 Polariza'on field decomposed into E/B modes Density perturba'ons produce only E modes Gravity waves produce E and B modes

6 Are there other ways to detect PGW? Gravita'onal Lensing: Ellip'ci'es of background galaxies also can be decomposed into E/B Can primordial gravita'onal waves be detected in large surveys which measure galaxy shapes?

7 Signal/Noise too small; largest on large scales Noise 2 nd order effects PGW Dodelson, Rozo, & Stebbins (2003) Sarkar et al. (2009)

8 RedshiP space distor'ons in futuris'c 21 cm surveys? Rela've contribu'on of PGW to scalars Bharadwaj & Sarkar (2009)_

9 Ambi'ous Plans for the coming Decade Baumann et al. (2008)_

10 Gravita'onal Wave amplitude pins down physics driving Infla'on Baumann et al. (2008)_

11 Challenge Scien'fic Risk: What if gravita'onal wave amplitude is too small? Other science with CMB Polariza'on: Lensing Reioniza'on Non gaussianity Magne'c Fields Exo'c Physics

12 Lensing of the CMB Unlensed T Unlensed E Deflec'on Field Lensed T Lensed E Lensed B Hu & Okamoto 2002

13 One Nasty Aspect of Lensing E-modes turn into B-modes

But lensing also provides a unique opportunity to measure the projected poten'al Hu & Okamoto 2002 Hirata & Seljak 2003 Projected potential Optimal

14 But lensing also provides a unique opportunity to measure the projected poten'al Hu & Okamoto 2002 Hirata & Seljak 2003 Projected potential Optimal Quadratic Likelihood Requires high resolu'on polariza'on measurements The sky has 600 of these fields! Invaluable informa'on for a wide variety of projects

15 I. De lens the E B contamina'on Improvement in Error on r with de-lensing Smith et al. (2008)_

16 II. Sta's'cs of the Projected Poten'al This power spectrum depends on, e.g., neutrino masses since neutrinos free stream out of over dense regions, leading to shallower poten'al wells on small scales Smith et al. (2008)_

17 Dis'nguish Normal from Inverted Hierarchy Smith et al. (2008)_

18 Reioniza'on Large scale polariza'on contains informa'on about the reioniza'on history of the universe. Planck WMAP CMBPol Zaldarriaga et al. (2008)_

19 Most powerful probe of early CMBPol reioniza'on WMAP Planck Might contain clues about DM annihila'on Zaldarriaga et al. (2008)_ Slatyer et al. (2008)_

20 Mysteries on the Horizon

21 E.g., History of Tunneling from False Vacuum to False Vacuum Large GW amplitude Expect PGW only near the horizon, with amplitude propor'onal to curvature. This would produce a completely different spectrum of B modes. 60 e folds of Infla'on Freivogel et al. (2005)_

22 Lensing B modes as Confirma'on The cross correla'on of CMB w/ Lensing is independent of the systema'cs in each (e.g. foregrounds, PSF distor'ons) The noise on this measurement is: So the Signal to Noise is:

23 Compute the Correla'on Coefficient The B mode moments are related to (Q,U) via where 2 Y lm are spin w spherical harmonics Large angle B modes come from the quadrupole at reioniza'on: Scagering rate Quadrupole Dvorkin, Peiris, & Hu (2008)_

25 Compute the power spectrum Use: The power spectrum reduces to a integral over k with

26 Go through a similar set of steps with lensing

27 Cross Correla'on is Large For a flat spectrum, α=2/3 This might be a viable way to add to our knowledge of gravita'onal waves on the horizon!

There is compelling evidence for new physics far beyond the Standard Model with extraordinary

28 My 2 pence to Panel Discussion Do we all agree with the statement: There was an early epoch during which the comoving Hubble radius decreased? There is compelling evidence for new physics far beyond the Standard Model with extraordinary proper'es We are now in the business of finding the right model for this early accelera'on Gravita'onal Waves (there or not) will help immensely

29 2020: Scenario I B modes detected by Planck and ground based experiments Gravita'onal wave amplitude precisely determined by CMBPol Scale of infla'on together with SUSY discovery at LHC leads to unified model for dark mager and infla'on

30 No B modes detected 2020: Scenario II Primordial Non Gaussianity detected (not expected in simple infla'on models but predicted in some alterna'ves) Cosmology in disarray: Is infla'on right? (Russians say yes; easy to construct models which fit data) Alterna'ves?

31 What can we do with this? Clean up B-mode contamination and measure even small tensor component Probe inflation even if energy scale is low Knox & Song; Kesden, Cooray, & Kamionkowski 2002

32 Smith et al. (2008)_

33 The obvious effect of redirec'on is to smooth out the peaks Seljak 1996

34 Leading to percent level changes of the acous'c peaks Lewis 2005

Weak gravitational lensing of CMB

Weak gravitational lensing of CMB (Recent progress and future prospects) Toshiya Namikawa (YITP) Lunch meeting @YITP, May 08, 2013 Cosmic Microwave Background (CMB) Precise measurements of CMB fluctuations