BICEP2 Results & Its Implication on inflation models and Cosmology Seokcheon Lee 48 th Workshop on Gravitation & NR May. 16 th. 2014

OUTLINE Cosmic Microwave Background Physics –Temperature Anisotropies –Polarization Implication of B ackground I maging C osmic E xtragalactic P olarization 2 –Data –Interpretation –Constraints on Inflation Models –Alternative Interpretations on its results Conclusions th Workshop on GRAV&NR (SLEE/KIAS)

CMB Spectra Spring-Yonsei Workshop (SLEE/KIAS) 3

CMB Physics : Temperature Anisotropies The Universe was in thermal equilibrium when the last scattering happened We obtain the blackbody spectrum with average T = K Last Scattering : when the photon is decoupled with electron th Workshop on GRAV&NR (SLEE/KIAS) 4

CMB Physics : Temperature Anisotropies This is much colder than the H ionization energy (13.6 eV) After LS, the photon freely propagates to us (exception reionization) What we see is the fossil of the standing wave between photon and baryon Deviation from Average T : Ensemble Average of this small deviation is called Temperature Power Spectrum th Workshop on GRAV&NR (SLEE/KIAS) 5

CMB Physics : Temperature Anisotropies Measure the anisotropy of T Measuring the directional difference of T (average doesn’t work) th Workshop on GRAV&NR (SLEE/KIAS) 6

CMB Physics : Temperature Anisotropies General solution Ω cr th Workshop on GRAV&NR (SLEE/KIAS)

CMB Physics : T-E-B contaminations Temptation to measure GHz th Workshop on GRAV&NR (SLEE/KIAS) 8

Polarization : How to generate E & B-mode ? Generating E-mode (linear polarization) –From both scalar and tensor perturbations th Workshop on GRAV&NR (SLEE/KIAS)

B-mode Polarization : How to generate B-mode ? Generating B-mode –From tensor perturbation (h) –From converting E-mode into B-mode (Gravitational lensing, Birefringence, primordial magnetic field) th Workshop on GRAV&NR (SLEE/KIAS)

B-mode Polarization : Why Important E & B modes around hot and cold spots Gravitational wave : Unique (?) channel to generate B-mode th Workshop on GRAV&NR (SLEE/KIAS)

CMB Physics : Temperature and Polarization N = ln[ ((10E16 GeV)/(10E-4 eV))] = 29 * ln[10] = th Workshop on GRAV&NR (SLEE/KIAS) Limited by cosmic variance if only consider T : Knox & Turner (94) r < 0.1

Implication of BICEP2 : why BICEP2 ? Ground based south pole / starting from Nov Frequencies : 100 (BICEP1), 150 GHz (BICEP2) / 26cm aperture Bolometer / 512 antenna (will be updated to 2560 antenna) Fig from BICEP th Workshop on GRAV&NR (SLEE/KIAS)

Why BICEP ? II Comparison for CMB polarization experiments (G : ground, HEMT : High-Electron- Mobility-Transistor, TES : Transition Edge Sensors ) NAMEBEGINBASIS/LO C FrequencyAmplifierTargets AMiBA2002G/Hawaii86-102Interferome ter SZ, Pol BICEP2005G/South Pole 100, 150BolometerLarge scale Pol CBI (DASI) (99-03) G/Chille (SP) 26-36HEMTSmall scale QUaD G/ SP100, 150BolometerSmall scale Pol EBEXFutureBallon/Anta rctica BolometerInflation GW POLARBE AR 2011G/Chille150Antenna- Coupled TES Lensed B QubicFutureG/97,150,230Bolometer / TES Intermediat e B SPOrtFutureSpacePol SPT2006G/SP90, 150, 220 Pol SPIDER2011Balloon90,150,220BolometerLarge scale Pol Planck2009Space30-857HEMT/Bolo meter th Workshop on GRAV&NR (SLEE/KIAS)

Instrument : Optics th Workshop on GRAV&NR (SLEE/KIAS)

Instrument th Workshop on GRAV&NR (SLEE/KIAS)

Foreground Removal : Contaminations Contamination sources & Sensitivity th Workshop on GRAV&NR (SLEE/KIAS)

Planck & BICEP : Dust Contamination Planck (May ) 353 GHz, whole sky BICEP2 (Mar ) Part of sky

Problems in Foreground Remove Not much is known about the polarization of foregrounds Understanding and removing foregrounds are critical for Polarization detection Independent Component Analysis (ICA) used in T None of studies take into account the impact of foregrounds in the presence of lensing and instrumental systematics Lack of a polarized dust map (BICEP relies on Planck data for this) –BICEP considered several models (FDS, BSS, LSA, PSM, DDM1 p.12) –Important because this affects the result of r (Fig. 6 & 11) th Workshop on GRAV&NR (SLEE/KIAS)

Results th Workshop on GRAV&NR (SLEE/KIAS)

Results : continued th Workshop on GRAV&NR (SLEE/KIAS)

Connection between Inflation models and CMB

Properties from CMB polarization

Scale of Inflation

Inflaton rolling distance

Constrain on Superstring

Constraints on Inflation Models I Slow roll parametersObservable quantities in terms of slow roll parameters to first order (Liddle & Lyth 00) th Workshop on GRAV&NR (SLEE/KIAS)

Constraints on Inflation models Prefer simple inflation? Rule out many r < 10E-5 models? Not really, it can’t have large running index Does BICEP2 confirm large r if we trust their data? (assume their systematic is correct) th Workshop on GRAV&NR (SLEE/KIAS)

Alternative Interpretations Many alternative ideas are possible (r = 0.1 still work) –Any other mechanism to create large scale B- mode in addition to GW? –Lowering the scalar amplitude As (Peloso et.al ) –Primordial Magnetic field (Bonvin et.al ) –Alleviate Bunch Davies vacuum (Collins et.al ) Cause the blue tilt nT > 1 – Strongly against this, because it costs changes in Temperature power spectrum (however it’s still consistent with error limit of T th Workshop on GRAV&NR (SLEE/KIAS)

Conclusions BICEP2 shows the first B-mode signal (still need to investigate the origin of this signal) It might show that we are under the right track to understand the Universe For the data interpretation, we still need to understand many others –Need better control for foreground contamination –Need to suspect for alternative interpretations and mechanism Stay tune for KECK and PLANCK th Workshop on GRAV&NR (SLEE/KIAS)