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The BINGO radio telescope and 21 cm Cosmology

The BINGO radio telescope and 21 cm Cosmology. Filipe B. Abdalla On behalf of the Bingo Collaboration (just went through our CDR). Talk outline. Cosmological relevance The BINGO telescope Current status. Era of precision cosmology. Cosmology is now in a golden area

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The BINGO radio telescope and 21 cm Cosmology

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  1. The BINGO radio telescope and 21 cm Cosmology Filipe B. Abdalla On behalf of the Bingo Collaboration (just went through our CDR)

  2. Talk outline • Cosmological relevance • The BINGO telescope • Current status

  3. Era of precision cosmology • Cosmology is now in a golden area • Standard ΛCDM model appears to be the best descripton so far! • But still major questions remain! • Inflation (t<10-32 s) • Dark energy CMB map from Planck collaboration et al. (2016)

  4. Baryon Acoustic Oscillations (BAOs) Planck collaboration (2016) • Acoustic waves imprinted on CMB 380,000 years after Big Bang • Acoustic scale set by distance light travelled at that time • Known precisely from CMB power spectrum • D=149 ± 0.6 Mpc • BAO scale imprinted on all matter in the Universe • Use as a “standard ruler” Credit: Chris Blake

  5. Alternative to optical BAO: HI Intensity mapping Use relatively large beam on the sky • Measure HI *fluctuations* • Similar to CMB, using • HI intensity mapping can be used as mass tracer, probing distortions in redshift space • No competition in the radio • Complementary to large optical surveys • Large beam on the sky (≈1 deg) contains many galaxies. • HI signal is measured through its overall intensity

  6. Importance of confirmation! Baryon Acoustic Oscillations in the Lyα forest of BOSS DR11 quasars. T. Delubac et al. [BOSS Collaboration] – A&A 574, A59 (2015), arXiv: 1404.1801 • From adjusting the BAO peaks and combining with the ΛCDM fiducial values from Planck+ WMAP: • Values differ: 1.8σ from Planck+WP; • 1.6σ from WMAP9+ACT+SPT Constraints on (DA/rd,DH(=H/c)/rd) Conclusion: Approximately 2σ below the value of DH And 2σ above the value of DA compared to the ΛCDM prediction. NOT THE ONLY TENSION IN THE MODEL!

  7. Why BAO in radio and in total intensity? • Complementary to optical data, different systematics • Decay time of HI hyperfine transition is ~ 10^15 seconds, but, 75% of visible matter in the Universe is made of H… • Efficient alternative for measuring a large number of galaxies individually (plus integrating the signal “alla” CMB allows for the reuse of a vast experiment in instrumentation and data analysis) • Interferometers are excellent instruments for these measurements, but are expensive and hard to operate and mantain • Single-dish instruments have been used recently, but with no positive results (although one should wait for CHIME and FAST) • Approach: single-dish, many horns X single horn per dish Battye, R.A. et al. MNRAS (2013) and arXiv:1610.06826 Wuensche, C. A. et al. arXiv:1803.01644

  8. Talk outline • Cosmological relevance • The BINGO telescope • Current status

  9. BINGO playersBAOs from Integrated Neutral Gas Observations

  10. BINGO concept (revised) Key specifications • Dish diameter : 40m • Resolution : 0.67 deg • Frequency range : 960 - 1260MHz • Z interval: z=0.13 - 0.48 (Δz<0.05) • Number of feeds : 50 (dual pol.) • No cryogenics : Tsys ≈ 50K • Pixel temperature ~ 100 μK • Digital correlation receiver • Channel resolution ~ 1 MHz • Most t/x components “off-the-shelf” Key specifications • Horn largest diameter: 1.9m • Horn length: 4.3m • Focal plane size: 15°x10° ~21x14m Survey Design • Observation time : 1 year on source • Area : 15 x 200 deg2 – drift scan Telescope with 1 45-m and 1 38-m wire-mesh dishes (No moving parts) Guiding principle : simplicity !

  11. The HI signal power spectrum Cosmological HI signal is weak! (≈100 μK rms) and on degree scales BAOs Total HI signal l≈(200/θ) degrees

  12. Frequency windows and FWHM graphs from Battye et al., 2013

  13. Correlation receiver • 1/f knee frequency of typical receivers is ≈1 Hz • To achieve 1mHz we need : • - Input matching to < 3% • - Hybrid accurate to < 1.5% • Probably go with digital backend after 1st LNA Bigot-sazy et al. 2015

  14. Component separation • Dominant foregrounds are expected to be spectrally smooth • HI signal fluctuates in frequency, allowing for it to be extracted • Simple PCA can do a remarkable job by removing the first few eigenmodes of the freq-freq covariance matrix • Caveat: assumes calibration is PERFECT • New methods using frequency and spatial info can be found in Olivari et al. (2015) Bigot-Sazy et al. 2015

  15. Data analysis efforts • HI power spectrum reconstruction (Olivari et al., 2015) • Cosmological parameters forecast (Olivari et al. 2017) • Collaboration is improving these: Methods implemented: • GMCA, FASTICA, PCA, GNILC. HI input HI reconstructed Noise

  16. BAO “Hubble diagram”

  17. Forecasts:

  18. (We will have an ultra-deep large-area spectral survey at 960-1260 MHz) Additional science with BINGO • BAOs contain additional information • Matter density • Redshift distortions • Anisotropic BAOs… • Life history of hydrogen • Radio recombination lines • Galactic continuum • Fast radio bursts (BINGO is an ideal survey instrument! est. 1 detection/week) • Pulsar science and GR science (will time same objects again and again).

  19. Talk outline • Cosmological relevance • The BINGO telescope • Current status

  20. Project status • BINGO is under construction! • Strong collaboration has been formed • About 80% completely funded • Partnership has the expertise including • Cosmology/astronomy (BR/UK/China/CH) • Receivers, antennas, telescopes, engineering (INPE/UK) • 80m antenna range with 5m shielded room (INPE/CH) • Local support / engineering / EM facilities / Companies support (UFCG) • Students/post-docs interest-> knowledge exchange with Brazil • Brazil is hosting 3 pos-docs working on BINGO at the moment, 2 foreigners • M.Sc. and Ph.D. students both from USP and INPE to attack problems related to BINGO subsystems

  21. 3-D model of optical design Secondary mirror Horn array (detectors) Courtesy Bruno Maffei & Adrian Galtress Primary mirror

  22. Receiver status

  23. Challenge: BINGO horns are big! • Aluminum horns (6060 T4 alloy) • Mass: 347 kg, not including screws and bolts, which may add ~ 30 kg to the unit • Number of rings: 127

  24. Bingo Horns - Aluminum • “The BINGO horns: design, fabrication and EM characterization” (in preparation). To be submitted either to: • Journal of Astronomical Telescopes, Instruments and Systems or • Journal of Astronomical Instrumentation Dimensions Length: 4318 mm Mouth opening: 1900 mm Throat opening: 250 mm

  25. 6 month RFI campaign for site selection. Paraíba sites Paraíba sites Uruguay sites Uruguay sites

  26. Still concerns about airplane coverage • “BINGO: RFI measurements and site selection” (Peel et al. 2018) submitted either to: • Journal of Astronomical Telescopes, Instruments and Systems or • Journal of Astronomical Instrumentation • (Collaboration decision in 2019)

  27. More to come soon Thank you! Please visit us at http://www.bingotelescope.org

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