BINGO: HI Intensity Mapping using a novel single-dish radio telescope

Tianyue Chen (on behalf of the BINGO collaboration)

Supervisors: Prof. Clive Dickinson Prof. Richard Battye Prof. Ian Browne

Jodrell Bank Centre for Astrophysics The

Nov 2016, Durban, South Africa Introduction

• Era of “precision ” Collaboration, 2013, XV • ΛCDM model works very well • Cosmological parameters - ~1% precision (mostly from CMB)

• The future - testing and refining this model: • New cosmological probes (e.g., BAOs) • Combining multiple probes Baryon Acoustic Oscillations (BAOs)

• What is it? Acoustic waves imprinted on CMB Imprint on all matter in the Universe

• Why BAO? Precisely known acoustic scale D= 147.4±0.3 Mpc Standard ruler --- Universe expansion vs. redshift --- Constrain dark energy

• Requirement? Limited by statistics --- require large sample size (HI) Intensity Mapping in a nut-shell

• What is Intensity Mapping Keywords: Emission line Large scale structure fluctuations Unresolved individual galaxies

• Benefits Relatively cheap and efficient 3D information --- 2D angular size + 1D redshift (obs. Freq.) HI - Good tracer of mass on LSS

Large beam on the sky (~1 deg) contains large number of galaxies The HI (21cm) power spectrum

Battye et al 2013 Intensity Mapping with SKA Single-dish (“autocorrelation”) mode -- lower z, more sensitive!

Bull et al. (2015) BINGO Concept

BAOs In Neutral Gas Observations

• Key Specifications: • Dish diameter : 40 m • Resolution: ~2/3 deg • Frequency range : 960 - 1260 MHz (z=0.12-0.48) • Channel width ~1 MHz (Δz<0.05) • Number of feeds: 50+ (dual pol) • Diameter of feed horns: ~1.7m • Field-of-view: ~15×15 deg2 • No cryogenic cooling : Tsys ~ 50K Survey Design • Digital correlation receiver • 2 years observing (~1 year on source) • Majority of receiver components “off-the-shelf” • Area:15°×200°(-5°declination)

Guiding principle : simplicity! Site selection

Quary Castrillon, near the town of Minas de Corrales, in Northern Uruguay

~40 Focal plane array m

Primary mirror Secondary mirror Optical design by Bruno Maffei. Drawings by Adrian Galtress. Topographical information from local mining company. • U. Sao Paolo, Brazil BINGO players • Elcio Abdalla (P.I.), Raul Abramo, Andreia Pereira de Souza (engineer), Benjamim Galvão (engineer, industry liaison), Marcos Lima • INPE, Brazil • Alex Wuensche, Thryso Villela, Renato Branco (engineer) • U. Montevideo, Ministry of Communications, Uruguay • Gonzalo Tancredi, Manuel Calas, Emilio Falco, Ana Mosquera • JBCA, Manchester, UK • Richard Battye, Ian Browne, Tianyue Chen, Peter Dewdney (SKAO), Richard Davis, Clive Dickinson, Keith Grainge, Stuart Harper, Lucas Olivari, Mike Peel (-> FAPESP fellow), Mathieu Remazeilles, Sambit Roychowdhury, Peter Wilkinson • ETH, Zurich, Switzerland • Alex Refregier, Adam Amara, Christian Monstein • UCL, London, UK • Filipe Abdalla • IAS, Paris, France SCIENTIFICALLY-LED by University of Manchester • Bruno Maffei (ex-Manchester) FUNDED by FAPESP in Brazil • U. Cardiff, UK • Giampaolo Pisano TELESCOPE in Uruguay • UKZN, South Africa COLLABORATION from UK, BR, UY, CH, SA, FR • Yin-Zhe Ma (ex-Manchester) • U. Portsmouth, UK • Alkistis Portsidou (ex-Manchester) It is not going to be easy!

• Large telescope! -> Novel horn fabrication • 1/f noise -> Correlation receiver • Radio Frequency Interference (RFI) -> Mobile-quiet frequency band choice • Bright foreground emissions! -> Component separation technique • Diffuse Galactic radio emission • Extragalactic sources • Calibration and stability -> Use moon for calibration • Sidelobe pick-up -> Careful optical design

• Atmospheric fluctuations -> ΔTatm = 0.01 mK < < ΔTther = 0.1 mK • …. BINGO horns fabrication

• 1.7 m diameter • 4.7 m in length • 50-60 of them! • Corrugated - low sidelobe response • Foam metalised (copper tape!) sheets

• Cheap • Light • Easy to make • and they seem to work!

Courtesy: Adam Colclough & Ian Browne BINGO BAO Hubble diagram BINGO sensitivity

5-7σ BAO detection

δkA/kA ~ 0.024

Much cosmological information from the HI power spectrum itself (Olivari et al., in prep.) BINGO Forecast: wCDM Approach: full shape of the HI power spectrum ● Ideal case (no foregrounds): w = -1.01±0.05 (Thermal noise)

● Foregrounds: w = -1.01±0.05 (using GNILC)

● Redshift-depend HI bias: (power-law model with 3 parameters) w = -1.02±0.07 (Thermal noise)

● Wavenumber-depend HI bias: (power-law model with 3 parameters) w = -0.93±0.06 (Thermal noise) Olivari et al. 2017 BINGO×Optical Galaxy Survey

Surveys: -21 cm: BINGO -Optical: DES, LSST

Methods: 1.Fisher Matrix forecast 2.Simulation 3.Real data

Expected Results:

-Cosmological parameter constraints, e.g., f(z)δ8, bHIδ8 -Astrophysics study, e.g., optical depth, etc. Conclusions and Project Status

 BINGO is a competitive BAO experiment using HI intensity mapping idea -Total cost $4M;FAPESP agreed $3M -Pathfinder for SKA

 Timeline End of 2016:Phase I – completion of receiver chain 2017-2018: Phase II – Building of telescope 2019-2020+:First scientific results