Wei-Tou NiDepartment of Physics

National Tsing Hua University[1] W.-T. Ni, http://astrod.wikispaces.com/file/view/GW-classification.pdf

 (MPLA 25 [2010] pp. 922-935; arXiv:1003.3899v1 [astro-ph.CO]).

[2] S. di Serego Alighieri, W.-T. Ni and W.-P. Pan, Astrophys. J. 792, 35 (2014).

[3] Mei, Ni, Pan, Xu, di Serego Alighieri, Ap J accepted; arXiv:1412.8569

Gravitational Waves:Spectrum Classification

2015.04.07 Beijing GWs: Spectrum Classification W.-T. Ni 1

Complete GW Classificationhttp://astrod.wikispaces.com/file/view/GW-classification.pdf

 (MPLA 25 [2010] pp. 922-935; arXiv:1003.3899v1 [astro-ph.CO])

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Space Detection: LF (100 nHz- 100 mHz)

& MF (100 mHz- 10 Hz)

Complete GW Classification (I)

Ultra high frequency band (above 1 THz): Detection methods include Terahertz resonators, optical resonators, and ingenious methods to be invented.

Very high frequency band (100 kHz – 1 THz): Microwave resonator/wave guide detectors, optical interferometers and Gaussian beam detectors are sensitive to this band.

High frequency band (10 Hz – 100 kHz): Low-temperature resonators and laser-interferometric ground detectors are most sensitive to this band.

Middle frequency band (0.1 Hz – 10 Hz): Space interferometric detectors of short armlength (1000-100000 km).

Low frequency band (100 nHz – 0.1 Hz): Laser-interferometer space detectors are most sensitive to this band.

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Complete GW Classification (II)

Very low frequency band (300 pHz – 100 nHz): Pulsar timing observations are most sensitive to this band.

Ultra low frequency band (10 fHz – 300 pHz): Astrometry of quasar proper motions are most sensitive to this band.

Extremely low (Hubble) frequency band （ 1 aHz – 10 fHz): Cosmic microwave background experiments are most sensitive to this band.

Beyond Hubble frequency band (below 1 aHz): Inflationary cosmological models give strengths of GWs in this band. They may be verified indirectly through the verifications of inflationary cosmological models.

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Improved Upper Limits on the Stochastic Gravitational-Wave Background from

2009-2010 LIGO and Virgo DataarXiv1406.4556

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Primordial Gravitational Waves[strain sensitivity (ω^2) energy sensitivity]

-18.0 -14.0 -10.0 -6.0 -2.0 2.0 6.0 10.0-24.0

-22.0

-20.0

-18.0

-16.0

-14.0

-12.0

-10.0

-8.0

-6.0

-4.0

-2.0

0.0

(a)

Nv = 3.2

ms pulsars

(b) String

LIGO or VIRGO

bar-intf

LISA

strings

cosmology

WMAP

ASTROD(correlation detection)

Super-ASTROD

inflation

Nv = 4

(c) cosmic

LIGO II/LCGT/VIRGO II (2 adv intf)

Log f [[[ [f(Hz)]

Log [h02Ω

gw]

2 intf

(single intf)

‘Average’

ExtragalacticExtrapolated

*

*

DECIGO/BBO-grand(correlation detection)ASTROD

Super-ASTROD (correlation detection)

GWs: Spectrum Classification W.-T. Ni

CMB observations7 orders or more improvement in

amplitude, 15 orders improvement in power since 1965

1948 Gamow – hot big bang theory; Alpher & Hermann – about 5 K CMB

Dicke -- oscillating (recycling) universe: entropy CMB 1965 Penzias-Wilson excess antenna temperature at 4.08

GHz 3.5±1 K 2.5 4.5 (CMB temperature measurement ) Precision to 10-(3-4) dipolar (earth) velocity

measurement to 10-(5-6) 1992 COBE anisotropy meas. acoustic osc. 2002 Polarization measurement (DASI) 2013 Lensing B-mode polarization (SPTpol) 2014 POLARBEAR, BICEP2 and PLANCK (lensing & dust B-

mode)2015.04.07 Beijing GWs: Spectrum Classification W.-T. Ni 7

Example sensitivity goals at 2008: Litebird (also CMBpol and B-POL)

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Constraints on Tensor-to-Scalar Ratio r ( nt/ns) before

2013.09.

Experiment ConstraintGoal/

Perspective (precision)

WMAP 9 < 0.38

WMAP 7 + ACT < 0.28

WMAP 7 + SPT < 0.18

PLANCK + WMAP Polarization

< 0.11 (2σ)

PLANCK 0.0?

QUIET (1st session) 0.35+1.06– 0.87 (43 GHz) 0.1 (43 GHz)

QUIET (2nd session) < 2.7 (2σ) (95 GHz) 0.01 (95 GHz)

POLARBEAR 0.007

B-pol, CMB-pol, Litebird 0.0012015.04.07 Beijing GWs: Spectrum Classification W.-T. Ni 9

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BICEP-2

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The BICEP-2 team has a lot to be proud of. They made a wonderful instrument, and collected great data. N. Czakon

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Three processes can produce CMB

B-mode polarization observed

(i) gravitational lensing from E-mode polarization (Zaldarriaga & Seljak 1997), (ii) local quadrupole anisotropies in the CMB within the last scattering region by large scale GWs (Polnarev

1985) (iii) cosmic polarization rotation (CPR) due to pseudoscalar-photon interaction (Ni 1973; for a review, see Ni 2010). (The CPR has also been called Cosmological Birefringence)

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consistent with no CPR detection

The constraint on CPR fluctuation is about 1. 5◦.

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NEW CONSTRAINTS ON COSMIC POLAR-IZATION ROTATION FROM DETECTIONS OF

B-MODE POLARIZATION IN CMBAlighieri, Ni and Pan

Fitting with dust, GWs and Lensing plus CPR

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Discussion & Outlook

GW detection Planck has releases its polarization data on the dust. Due to

Planck’s frequency coverage, we understand now that the dust foreground agrees with the BICEP2 B-mode observation. The GW interpretation needs to subtract this.

100 GHz Keck Array data will be available soon Three frequency BICEP3/Keck Array data (coming 2015?),

should be able to characterize foregrounds.BICEP/Keck has 2 more years

If r is small, it may take 5 years or more for next generation CMB experiments to come out to detect primordial GWs.

PTAs: any time around 2020; more data from binary orbit decays

Space: 20 years later, 2034 launch + 1 yr orbit transfer + Earth-based interferometer: 2015 +2015.04.07 Beijing GWs: Spectrum Classification W.-T. Ni 19

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Thank You！