cosmic microwave background polarization and detection of primordial gravitational waves n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Cosmic Microwave Background Polarization and Detection of Primordial Gravitational Waves PowerPoint Presentation
Download Presentation
Cosmic Microwave Background Polarization and Detection of Primordial Gravitational Waves

Loading in 2 Seconds...

play fullscreen
1 / 48

Cosmic Microwave Background Polarization and Detection of Primordial Gravitational Waves - PowerPoint PPT Presentation


  • 154 Views
  • Uploaded on

Cosmic Microwave Background Polarization and Detection of Primordial Gravitational Waves. Wen Zhao @ Depart. of Astronomy, USTC. 1. OUTLINE. CMB field and Polarization Primordial gravitational waves & CMB Conclusion. 2. Temperature and Polarization of the CMB. 3.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Cosmic Microwave Background Polarization and Detection of Primordial Gravitational Waves' - mark-olsen


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
cosmic microwave background polarization and detection of primordial gravitational waves

Cosmic Microwave Background Polarization and Detection of Primordial Gravitational Waves

Wen Zhao

@ Depart. of Astronomy, USTC

1

outline
OUTLINE

CMB field and Polarization

Primordial gravitational waves & CMB

Conclusion

2

slide5

Thomson Scatter and Generation of PolarizationTwo factors:** Temperature Anisotropies ** Free electronsTwo stages: @ recombination stage @ reionization stage

5

cmb power spectra
CMB power spectra

Density perturbation

Gravitational waves

r = 1

7

generation of rgws
Generation of RGWs

In the curved space-time, the vacuum state at the stage 1 naturally corresponds to the multi-particle state at a different stage 2.

If considering the Universe, we can assume the universe had a vacuum state of graviton at the initial stage. With the expansion of the Universe, but the radiation-dominant stage, the gravitons were naturally generated. (Grishchuk, 1974)

If the Universe had an exact de-Sitter expansion in the inflationary stage, the generated primordial power spectrum of RGWs is scale-invariance. The amplitude of the spectrum directly depends on the Hubble parameter, which directly relates to the energy scale of the early Universe.

13

cmb power spectra1
CMB power spectra

Density perturbations

Relic gravitational waves

r=1

18

detection in the cmb
Detection in the CMB

Method a:BB channel

But B-polarization is very small. When the noise is large, this channel is useless.

Method b:TT+EE+TE channels

Total TT = TT (dp,+) + TT (gw,+)

Total EE = EE (dp,+) + EE (gw,+)

Total TE = TE (dp,+) + TE (gw,-)

This method is limited by cosmic variance of d.p. When r<0.05, these three channels will be useless.

19

relic gravitational waves in wmap data
Relic gravitational waves in WMAP data

WMAP7 gives: r<0.36 at 95% C.L. (Komatsu et al 2010)

This constraint comes from TT+TE observations.

(Planck)TT + (WMAP9)TE + highL even give: r<0.11 at 95% C.L. (Planck Collaboration, 2013)

BB only gives r<2.1 at 95% C.L. (Komatsu et al 2010)

20

slide21
Why?
  • 1. All TT+TE data, the multipoles till to around 10,000
  • 2. Power-law form for d.p. is correct at least for four orders in scale
wmap tt te data l 100
WMAP TT+TE data (l<=100)

1. power-law forms for d.p. and g.w.

2. d.p. with running

5. piece-wise form for d.p. and g.w.

3. power-law d.p. and g.w., but l<100 data (red curves)

4. power-law d.p. and g.w., but l<100 data + SNIa + SDSS

24

detecting b mode polarization by planck
Detecting B-mode Polarization by Planck

1. Planck can B-polarization, only if r>0.05.

2. Planck can only detect the reionization peak at l<10.

3. Planck is notgood at for the detection of gravitational waves (I will explain it later!).

27

other projects
Other Projects

S/N is determined by two factors:

1) sky survey area2) noise level.

Planck:full sky but large noise

Ground:lower noise but small partial survey

CMBPOL or COrE:lower noise + full sky survey

30

various ground based experiments
Various ground-based experiments

Survey method: a small part of full sky for a long time.

Ground-based Experiments: QUaD, BICEP, QUIET, POLARBEAR, ABS, CLASS, ClOVER, QUIJOTE, ACTPOL, SPTPOL, QUBIC, KECK and so on.

Noise level: cosmic lensing limit.

In addition, balloon-borne experiments: EBEX, PIPER, Spider.

http://en.wikipedia.org/wiki/List_of_cosmic_microwave_background_experiments

32

slide34

BICEP1: Updated

(Barkast et al. 2014)

34

ideal cmb experiment
Ideal CMB experiment

Cosmic lensing generates the E-B mixtures, and forms a nearly white B-mode spectrum.

For the ideal experiment, where only the reduced cosmic lensing contamination is considered.

Detection limit:

46

conclusion
Conclusion

CMB polarization was formed in the recombination stage (z~1100) and reionization stage (z~10). Now, with the observing of Planck mission, as well as other detectors, CMB polarization (including TE, EE and BB) becomes one of the key probes of the early Universe.

Detection primordial gravitational waves, especially by the B-mode polarization, is one of the main tasks for the current and future CMB experiments, including Planck , ground-based experiments , CMBPol and ideal experiment .

BICEP2 has detected the signal of gravitational waves with r=0.2, which corresponds the energy scale of inflation . In principle, it can be confirmed by the forthcoming Planck polarization data at different multipole range.

47