RadioNet Workshop 22 september 2020 Latest calibration results from QUBIC: The Q&U Bolometric Interferometer for Cosmology Louise Mousset Advisors: Jean-Christophe Hamilton Steve Torchinsky Laboratoire AstroParticules & Cosmologie (APC) Université de Paris 1 mousset@apc.in2p3.fr
The Cosmic Microwave Background 1965: First observation by A. Penzias and R.W. Wilson ⇒ Nobel Prize (1978) 2
Cosmic Microwave Background (CMB) Plasma at thermodynamic Big-Bang equilibrium electron Nucleus Photon 3
Cosmic Microwave Background (CMB) Plasma at Expansion CMB emission, Recombination thermodynamic ~ 380 000 ans Big-Bang equilibrium Atom electron Nucleus Photons propagate freely in a Photon transparent Universe 3
Cosmic Microwave Background (CMB) Plasma at Expansion CMB emission, Recombination thermodynamic ~ 380 000 ans Big-Bang equilibrium Atom electron Nucleus Photons propagate freely in a Photon transparent Universe Black Body 3
Cosmic Microwave Background (CMB) Plasma at Expansion CMB emission, Recombination thermodynamic ~ 380 000 ans Big-Bang equilibrium Atom electron Nucleus Photons propagate freely in a Photon transparent Universe Black Body Temperature isotropy = + + 3
Cosmic Microwave Background (CMB) Plasma at Expansion CMB emission, Recombination thermodynamic ~ 380 000 ans Big-Bang equilibrium Atom electron Nucleus Photons propagate freely in a Photon transparent Universe 1992: COBE satellite, Black Body G. Smoot and J. Mather ⇒ Nobel Prize (2006) Temperature isotropy = + + 3
Temperatures anisotropies Origin: Density fluctuations in the primordial plasma. Credit: Planck, ESA → Constraints on cosmological parameters and contents of the universe. Issue: Foregrounds such as galactic dust emit in the same frequency range. 4 8
The CMB polarization Origin: Thomson scattering between photons and electrons in the primordial plasma. Electric field For each position on the sky, one can define the Stokes parameters: → Intensity (temperature) } Linear polarization y a b 45° x 5
The CMB polarization Origin: Thomson scattering between photons and electrons in the primordial plasma. Electric field For each position on the sky, one can define the Stokes parameters: → Intensity (temperature) } Linear polarization y a b 45° x E and B modes: ⇒ A global definition over the sky 5
Primordial B modes, a clue for inflation Inflation: Accelerated expansion phase right after the Big-Bang (~10 -34 s). Expansion factor: ~ 10 26 Metric Primordial Inflation gravitational waves Tensor Quantum E and B modes perturbations fluctuations of the inflaton 𝝔 Density fluctuations Scalar E modes perturbations Measuring the primordial B modes will put constraints on inflation models, especially on the value of the tensor to scalar ratio r: 6 11
Primordial B modes, a clue for inflation Inflation: Accelerated expansion phase right after the Big-Bang (~10 -34 s). Expansion factor: ~ 10 26 Metric Primordial ~10 nK !! Inflation gravitational waves Tensor Quantum E and B modes perturbations fluctuations of the inflaton 𝝔 Density fluctuations Scalar E modes perturbations Measuring the primordial B modes will put constraints on inflation models, especially on the value of the tensor to scalar ratio r: 6 12
Limit on the tensor to scalar ratio r Forecasts with the QUBIC data analysis pipeline ~ 2 times better than Posterior probability the current limit. 7
Summary Primordial fluctuations from inflation are imprinted in the temperature anisotropy and polarization of the CMB. Time 8
QUBIC as an interferometer 9
The QUBIC project Observation site: Argentina, Plato de la Puna (~5000m) Calibration at APC 10
An imaging interferometer Point source at infinity 11
An imaging interferometer Point source at infinity Images on the focal plane 11
An imaging interferometer Point source at infinity = + Images on the focal plane Synthesized or “dirty” image 11
An imaging interferometer Correlator Point source “Dirty image” at infinity = + Images on the focal plane Synthesized or “dirty” image 11
Filters Main optical elements Cryostat Rotating Half wave plate Polarizer Horn array Secondary mirror Focal plane Primary mirror (992 bolometers) Remark: The full instrument will have 2 focal planes centered at 150 and 220 GHz with 40 GHz band width each. 12
Self-calibration Well known technique in radio astronomy. [T. J. Cornwell, P. N. Wilkinson, A new method for making maps with unstable radio interferometers, 1981] Horn array (8x8) Switches Method : For 2 equivalent baselines, in case of a perfect instrument, the synthesized image on the focal plane should be identical. The measured differences are used to characterize systematic effects. [Bigot-Sazy et al., Astronomy & Astrophysics, 2013, vol. 550, p. A59.] Fringes on the focal plane created by 2 redondant baselines 13 one baseline on the horn array
Fringes measurement A quarter of the focal plane (17x17) Simulation taking into account optical aberrations One bolometer 14
QUBIC as a spectro-imager 15
Spectro-imaging Wide band 130 170 150 QUBIC observes in a wide band. Spectro-imaging allows us to split the wide band f (GHz) into multiple sub-bands in post processing . Maps I, Q, U 16 25
Spectro-imaging Wide band 130 170 150 QUBIC observes in a wide band. Spectro-imaging allows us to split the wide band f (GHz) into multiple sub-bands in post processing . Maps I, Q, U ⇒ Very useful to remove foregrounds Temperature Polarization 16 Credit: Planck, 2018 26
QUBIC beam is frequency dependent Source at 130 GHz scanned by a single detector : Measurement Simulation Calibration source El Scan in azimuth and elevation Az Point source (150 GHz) ∝ λ Synthesized beam for one detector 30 ° QUBIC 17
QUBIC beam is frequency dependent Source at 150 GHz scanned by a single detector : Measurement Simulation Calibration source El Scan in azimuth and elevation Az Point source (150 GHz) Synthesized beam for one detector 30 ° QUBIC 17
QUBIC beam is frequency dependent Source at 170 GHz scanned by a single detector : Measurement Simulation Calibration source El Scan in azimuth and elevation Az Point source (150 GHz) Synthesized beam for one detector 30 ° QUBIC 17
Spectro-imaging on the galactic dust Input Output Residuals Input Output Residuals Forecasts with the Polarization Q QUBIC data analysis pipeline Intensity I 5 bands at 220 GHz 15° radius patch on the galactic center 18
Spectro-imaging pixel by pixel Forecasts with the QUBIC data analysis Observation of the galactic dust pipeline Pixel area ~ 54 deg² Intensity as function of the frequency in one pixel Input sky convolved at the Reconstructed sky QUBIC resolution X X Dots and error bars being the mean and the standard deviation over independent noise realisations. 19
Summary Observing the CMB polarization allows us to test inflation models, a major issue in cosmology today. ➢ First light in Argentina next year. ➢ Bolometric Interferometry is a new concept that combines: ➢ the sensitivity of bolometric detectors ○ the instrumental systematics control of interferometers ○ Capability to perform spectro-imaging ➢ Special issue of JCAP in preparation: - QUBIC I: Overview and Science Program [in prep] - QUBIC II: Spectro-Polarimetry with Bolometric Interferometry [in prep] - QUBIC III: Laboratory Characterization [https://arxiv.org/abs/2008.10056] - QUBIC IV: Performance of TES Bolometers and Readout Electronics [in prep] - QUBIC V: Cryogenic system design and performance [https://arxiv.org/abs/2008.10659] - QUBIC VI: Cryogenic half wave plate rotator, design and performance Website: http://qubic.in2p3.fr [https://arxiv.org/abs/2008.10667] - QUBIC VII: The feedhorn-switch system of the technological demonstrator Facebook: https://www.facebook.com/qubiccosmo [https://arxiv.org/abs/2008.12721] 20 - QUBIC VIII: Optical design and performance [https://arxiv.org/abs/2008.10119]
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