Canadian Hydrogen Intensity Mapping Experiment (CHIME) Richard Shaw Figure 2: The CHIME telescope consists of five parabolic, cylindrical reflectors and associated radio
CHIME Collaboration UBC Graeme Addison Mandana Amiri Meiling Deng Mateus Fandino Kenneth Gibbs Carolin Hofer Mark Halpern Adam Hincks Gary Hinshaw Kiyo Masui Kris Sigurdson Mike Sitwell Rick Smegal Don Wiebe McGill Kevin Bandura J-F Cliche Matt Dobbs Adam Gilbert David Hanna Juan Mena Parra Graeme Smecher Amy Tang DRAO Tom Landecker Toronto/CITA Dick Bond Liam Connor Nolan Denman Peter Klages Laura Newburgh Ue-Li Pen Andre Recnick Jeff Peterson (CMU) Richard Shaw Keith Vanderlinde
CHIME Overview N 100m The CHIME telescope consists of five parabolic, cylindrical reflectors and associated ra and correlators. The structure is 100m 100m. Note the people in the N figure, for sca cope has no Transit moving radio parts, interferometer and maps half of the sky every day. Observe between 400-800 MHz 0.5 MHz spectral resolution 1280 dual pol antennas (T recv = 50K) 120 x 2 degree FoV 15 arcmin resolution Located at DRAO in BC Beam: ~120 x 2 deg
CHIME Overview N 100m The CHIME telescope consists of five parabolic, cylindrical reflectors and associated ra and correlators. The structure is 100m 100m. Note the people in the N figure, for sca cope has no Transit moving radio parts, interferometer and maps half of the sky every day. Observe between 400-800 MHz 0.5 MHz spectral resolution 1280 dual pol antennas (T recv = 50K) 120 x 2 degree FoV 15 arcmin resolution Located at DRAO in BC Beam: ~120 x 2 deg
CHIME Overview N 100m The CHIME telescope consists of five parabolic, cylindrical reflectors and associated ra and correlators. The structure is 100m 100m. Note the people in the N figure, for sca cope has no moving parts, and maps half of the sky every day. Science Goals Intensity mapping for BAOs Pulsar observations Radio transients Beam: ~120 x 2 deg
15 h 14 h Intensity Mapping 13 h Observe galaxies with 21cm line 12 h Automatically gives redshift Don t need to resolve individual galaxies 11 h Other experiments: BINGO(next talk), Tianlai, SKA(?) 10 h 0.00 0.05 0.10 Redshift z Chang et al, 2008; Wyithe and Loeb 2008
15 h 14 h Intensity Mapping 13 h Observe galaxies with 21cm line 12 h Automatically gives redshift Don t need to resolve individual galaxies 11 h Other experiments: BINGO(next talk), Tianlai, SKA(?) 10 h 0.00 0.05 0.10 Redshift z Chang et al, 2008; Wyithe and Loeb 2008
Survey Volume WiggleZ: 1.2 (h -1 Gpc) 3 BOSS LRG: 5.3 (h -1 Gpc) 3 Lyα: 37 (h -1 Gpc) 3 CHIME: 203 (h -1 Gpc) 3 Scaled such that: area of patch=volume of survey
Probing BAO Potentially 21cm could extend this to higher redshifts Anderson et al. 2013
Probing Dark Energy with CHIME 4 2 Planck 0 LCDM 2 0.1 DD M (z) / 100 Mpc 0.0 0.1 DH(z) / H 0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Redshift z
CHIME Status Fully funded ($11 million) Construction due to start in early 2015 Fully operational in 2016 What are we doing in the meantime?
CHIME Pathfinder 2x40m cylinders (vs 5x100m) 64 dual pol antennas per cylinder 256 correlated channels Currently operating (with reduced number of feeds)
CHIME Pathfinder
CHIME Pathfinder
CHIME Pathfinder
CHIME Pathfinder
Commissioning First light at the end of November with 8 feeds Installing full 256 feeds over the next month Cas A (single E-W
Dark Energy with CHIME Pathfinder 4 2 Planck 0 LCDM 2 0.1 DD M (z) / 100 Mpc 0.0 0.1 DH(z) / H 0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Redshift z
Data Analysis Analysis is challenging: Wide field at given instant (~ 120 x 2 degrees) Effectively an all sky survey (3π sr) Data volume (>~ 1 TB/day for pathfinder) Polarisation leakage Foreground removal (> 10 6 times brighter)
Unpolarised Foreground 480 460 440 420 400 270 280 290 300 500 Frequency / MHz 500 Polarised Foreground (Q) Frequency / MHz Frequency / MHz Simulated Sky d Foreground Problem 480 460 440 420 400 330 340 f / degrees 0K 350 360 21cm Signal 500 480 460 440 420 400 270 280 f / degrees 750 K 2K 290 300 f / degrees 2K 140 µk Foregrounds 106 times larger than signal 140 µk
m-mode transform Developed m-mode formalism Transit telescopes only (stationary noise) Naturally full sky and widefield. Exact (no UV plane) Breaks problem into statistically independent modes (efficient) Published in arxiv:1302.0327; arxiv:1401.2095 Enables an efficient cleaning of foregrounds: Use covariance of data to find a statistical separation (KL Transform/SN eigenmodes) Fully treats mode mixing effects
Unpolarised Foreground 480 460 440 420 400 270 280 290 300 500 Frequency / MHz 500 Polarised Foreground (Q) Frequency / MHz Frequency / MHz Simulated Sky d Foreground Cleaning 480 460 440 420 400 330 340 f / degrees 0K 350 360 21cm Signal 500 480 460 440 420 400 270 280 f / degrees 750 K 2K 290 300 f / degrees 2K 140 µk Foregrounds 106 times larger than signal 140 µk
Frequency Frequency Frequency 440 460 440 Foreground Cleaning 420 400 270 280 290 300 420 400 330 340 f / degrees 750 K 2K 480 460 440 420 420 400 270 280 290 300 500 480 460 440 420 400 330 340 140 µk 0.5 µk 2K 300 350 360 140 µk 21cm Signal 500 480 460 440 420 400 270 280 f / degrees 30 750µK K 290 f / degrees 2K f / degrees 30 0 KµK 440 Polarised Foreground (Q) Frequency / MHz 500 280 360 460 f / degrees Unpolarised Foreground 400 270 350 Frequency / MHz 0K Frequency / MHz S SimulatedFiltered Sky Foreground d 460 290 300 f / degrees 0.5 µk 2K 120 µk 140 Foreground residuals significantly smaller than signal 120 µk 140
Power spectrum Estimation Use Optimal Quadratic Estimator (Tegmark 1997) Fractional powerspectrum errors (blue is better) 0.25 NoPol FG No FG Full FG Full FG 1.00 0.70 0.20 0.50 k k / h Mpc 1 0.15 0.10 0.30 0.20 0.15 Subtraction works well into foreground wedge 0.10 0.05 0.07 0.00 0.00 0.04 0.08 k? / h Mpc 1 0.00 0.04 0.08 0.05
Summary CHIME is a new wide-field, low frequency radio interferometer intended for surveying Main goal: measure BAOs through Intensity Mapping Coming online in 2016 CHIME Pathfinder is currently taking data New techniques have been developed to address the data analysis challenges (optimality, foregrounds...)