Latest calibration results from QUBIC: The Q&U Bolometric - - PowerPoint PPT Presentation
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
RadioNet Workshop
22 september 2020
The Q&U Bolometric Interferometer for Cosmology
mousset@apc.in2p3.fr
Louise Mousset
Advisors: Jean-Christophe Hamilton Steve Torchinsky Laboratoire AstroParticules & Cosmologie (APC) Université de Paris 1
1965: First observation by
⇒ Nobel Prize (1978) 2
Cosmic Microwave Background (CMB)
Big-Bang Plasma at thermodynamic equilibrium electron Nucleus Photon
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Cosmic Microwave Background (CMB)
Big-Bang Plasma at thermodynamic equilibrium CMB emission, Recombination Photons propagate freely in a transparent Universe Expansion ~ 380 000 ans electron Nucleus Photon Atom
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Cosmic Microwave Background (CMB)
Black Body Big-Bang Plasma at thermodynamic equilibrium CMB emission, Recombination Photons propagate freely in a transparent Universe Expansion ~ 380 000 ans electron Nucleus Photon Atom
3
Cosmic Microwave Background (CMB)
Black Body Big-Bang Plasma at thermodynamic equilibrium CMB emission, Recombination Photons propagate freely in a transparent Universe Expansion ~ 380 000 ans electron Nucleus Photon Temperature isotropy
= + +
Atom
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Cosmic Microwave Background (CMB)
Black Body Big-Bang Plasma at thermodynamic equilibrium CMB emission, Recombination Photons propagate freely in a transparent Universe Expansion ~ 380 000 ans electron Nucleus Photon Atom
1992: COBE satellite,
⇒ Nobel Prize (2006)
Temperature isotropy
= + +
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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.
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For each position on the sky, one can define the Stokes parameters: Electric field
→Intensity (temperature)
The CMB polarization
Origin: Thomson scattering between photons and electrons in the primordial plasma.
x y b a
45°
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x y b a
45° For each position on the sky, one can define the Stokes parameters: Electric field
→Intensity (temperature)
The CMB polarization
Origin: Thomson scattering between photons and electrons in the primordial plasma. E and B modes:
⇒ A global definition over the sky
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Primordial B modes, a clue for inflation
Measuring the primordial B modes will put constraints on inflation models, especially on the value of the tensor to scalar ratio r: Quantum fluctuations
inflaton 𝝔 Primordial gravitational waves E and B modes E modes Density fluctuations Metric Tensor perturbations Scalar perturbations Inflation
Inflation: Accelerated expansion phase right after the Big-Bang (~10-34 s). Expansion factor: ~ 1026
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Primordial B modes, a clue for inflation
Measuring the primordial B modes will put constraints on inflation models, especially on the value of the tensor to scalar ratio r: Quantum fluctuations
inflaton 𝝔 Primordial gravitational waves E and B modes E modes Density fluctuations Metric Tensor perturbations Scalar perturbations Inflation
Inflation: Accelerated expansion phase right after the Big-Bang (~10-34 s). Expansion factor: ~ 1026
~10 nK !!
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Limit on the tensor to scalar ratio r
Forecasts with the QUBIC data analysis pipeline
~ 2 times better than the current limit. Posterior probability
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Time Primordial fluctuations from inflation are imprinted in the temperature anisotropy and polarization of the CMB.
Summary
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Observation site: Argentina, Plato de la Puna (~5000m) Calibration at APC
The QUBIC project
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An imaging interferometer
Point source at infinity
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Images on the focal plane
An imaging interferometer
Point source at infinity
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Images on the focal plane
An imaging interferometer
= +
Synthesized or “dirty” image
Point source at infinity
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Images on the focal plane
An imaging interferometer
“Dirty image”
Correlator
= +
Synthesized or “dirty” image
Point source at infinity
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Horn array Focal plane (992 bolometers) Polarizer Cryostat Rotating Half wave plate Filters Secondary mirror Primary mirror
Main optical elements
Remark: The full instrument will have 2 focal planes centered at 150 and 220 GHz with 40 GHz band width each. 12
2 redondant baselines
Fringes on the focal plane created by
Method : For 2 equivalent baselines, in case of a perfect instrument, the synthesized image on the focal plane should be
Horn array (8x8) Switches
[Bigot-Sazy et al., Astronomy & Astrophysics, 2013,
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]
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A quarter of the focal plane (17x17) One bolometer Simulation taking into account
Fringes measurement
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Spectro-imaging
150 130 170
f (GHz) Maps I, Q, U
Wide band QUBIC observes in a wide band. Spectro-imaging allows us to split the wide band into multiple sub-bands in post processing.
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Spectro-imaging
⇒ Very useful to remove foregrounds 150 130 170
f (GHz) Maps I, Q, U
Wide band QUBIC observes in a wide band. Spectro-imaging allows us to split the wide band into multiple sub-bands in post processing. Temperature Polarization
Credit: Planck, 2018 16
QUBIC beam is frequency dependent
Scan in azimuth and elevation
Source at 130 GHz scanned by a single detector: Measurement
Simulation
∝ λ
Az El 30 °
Calibration source QUBIC
Synthesized beam for one detector Point source (150 GHz) 17
Source at 150 GHz scanned by a single detector: Measurement
Simulation Scan in azimuth and elevation Calibration source QUBIC
Synthesized beam for one detector Point source (150 GHz) Az El 30 °
QUBIC beam is frequency dependent
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Source at 170 GHz scanned by a single detector: Measurement
Simulation Scan in azimuth and elevation Calibration source QUBIC
Synthesized beam for one detector Point source (150 GHz) Az El 30 °
QUBIC beam is frequency dependent
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Forecasts with the QUBIC data analysis pipeline 5 bands at 220 GHz 15° radius patch on the galactic center Input Output Residuals
Spectro-imaging on the galactic dust
Intensity I Polarization Q Input Output Residuals 18
Spectro-imaging pixel by pixel
Forecasts with the QUBIC data analysis pipeline Input sky convolved at the QUBIC resolution Reconstructed sky
Observation of the galactic dust Pixel area ~ 54 deg²
Intensity as function of the frequency in one pixel
X X
Dots and error bars being the mean and the standard deviation over independent noise realisations.
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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
Website: http://qubic.in2p3.fr Facebook: https://www.facebook.com/qubiccosmo Special issue of JCAP in preparation:
[https://arxiv.org/abs/2008.10667]
[https://arxiv.org/abs/2008.12721]
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