CHIME Vicky Kaspi Department of Physics, McGill Space Institute McGill University, Montreal, Canada
CHIME Talk Summary Combines FFT Telescope design with cylinders to achieve huge FOV for wide- field radio imaging with GBT- like sensitivity at very low cost Exploits technology from telecommunications and computer gaming industry COTS Covers unique phase space in radio astronomy Applications: 21 cm cosmology Radio transients Pulsars Interstellar medium
CHIME: Canadian Hydrogen Intensity Mapping Experiment Penticton, BC at DRAO 4 20 m x 100 m cylinders Transit telescope 256 dual- pol feeds per axis, 2048 input signals 400-800 MHz FOV: E- W 2.5 o - 1.3 o, N- S ~90 o Area of six hockey rinks The End Beam size 0.5 o - 0.3 o CFI- funded $12M CDN
Cylinder focuses light only in EW direction Gives us large FOV
FFT telescope in NS direction 256 beams per cylinder
\ 1024 beams from full 4- cylinder CHIME
System Overview Feeds, LNAs, Filters!"#$%&'#"()&'*+,(-(./0.$1*+ 23011&4(/0.$1*+2$''&40.$1+ FFT Shuffle Correlator GPU Cluster Figure courtesy K. Vanderlinde
CHIME Cosmology Science Goal Measure Baryon Acoustic Oscillations (e.g. Chang et al. Nature, 2010) Map redshifted HI to look for periodic fluctuations in matter power spectrum 400-800 MHz z=0.8-2.5 Cosmic standard ruler: see size evolve with z Superb constraints on Dark Energy Mapping the Observable Universe CHIME will: z! survey BAO measure the growth of space from 0.8<z<2.5 over a volume of ~400 comoving Gpc 3 1100 CMB 50 Reionization Age of Universe 9 5 3 2 1 SDSS 0 300ky 500My 7Gy 13.7Gy WiggleZ Big Bang CHIME Slide from K. Vanderlinde Matt.Dobbs@McGill.ca, CHIME Pulsar Workshop 2013-04 7 Figure from M. Dobbs
Cosmology Collaboration UBC Mandana Amiri Meiling Deng Mateus Fandino Ken Gibbs Mark Halpern Adam Hincks Gary Hinshaw Kiyo Masui Richard Shaw Kris Sigurdson Mike Sitwell Carolin Hofer McGill Kevin Bandura Jean-Francois Cliche Matt Dobbs Adam Gilbert David Hanna Gilbert Hsyu Juan Mena Parra Tristan Pinsonneault-Marotte Amy Tang Graeme Smecher DRAO Tom Landecker UofT Dick Bond Liam Connor Nolan Denman Peter Klages Laura Newburgh Ivan Padilla Ue-Li Pen Andre Recnik Keith Vanderlinde Kendrick Smith Jeff Peterson (CMU)
CHIME structure as of July 23
Mystery of Fast Radio Bursts Few- ms radio bursts DM >> DM MW Some scattered ~3 x 10 4 /sky/day Origin unknown Likely cosmological Other models too Not microwave ovens Thornton et al. 2013 CHIME can be an excellent FRB detector!
Figure by Erik Madsen
CHIME/FRB Collaboration CHIME Cosmology team, plus: Vicky Kaspi (McGill U., PI) Alex Josephy, Erik Madsen, Shriharsh Tendulkar Ingrid Stairs (UBC) Cherry Ng Scott Ransom (NRAO) Paul Demorest (NRAO) Bryan Gaensler (U. Toronto)
CHIME/FRB Project CFI- funded $5.6M for onsite GPU- based back- end Significant changes to CHIME GPU- based correlator Output power with 8 bits, 1- ms cadence, 4096 freq channels for each of 1024 beams Real- time trigger of baseband buffer for post- analysis Simultaneous with cosmology experiment Current status: FRB back- end under design Study of different dedispersion, burst detection algorithms Predicted event rate depends on design: Minimize GPU power consumption (~140 kw max) but maximize sky coverage (no. beams searched)
Figure by Keith Vanderlinde
FRBs and CHIME What we want Thousands of events for event rate, flux distribution, angular distribution, DM distribution, scattering vs DM, Can CHIME deliver? Yes Detect or rule out repetition Real- time triggers Yes Yes Arcsecond localization Sensitivity to linear polarization vs freq, vs time Maybe, if optical/x- ray counterparts exist, are long- lived & bright Yes
CHIME FRB Localization: work in progress Animation by Erik Madsen
Cute time smearing trick Correlator starts with full phase info can coherently dedisperse to user- selected value Observe in runs optimized for different DMs Reduces bias in measured DM distribution
CHIME Sensitivity to Pulsars Large area, wide bw CHIME can detect nearly all pulsars above horizon Separate NSERC funding for pulsar backend: 10 simultaneous steerable beams 24/7 Coherently dedispersed, dual polarization Online folding for monitoring known pulsars Binaries (GR tests, eclipse studies, LMXB transitions, ) ISM monitoring (NANOGrav/IPTA, DM variations, scattering, scintillation, RMs, ESEs ) Nullers, mode changers, magnetospheric phenomena Glitches, timing noise Radio magnetar outbursts Slow pulsar searching possible too (MSPs too hard) Stack searches RRATs for free from FRB detector Cute new tricks: few ms slew time, excellent flux calibration
CHIME Sensitivity to Pulsars Courtesy Cherry Ng
Conclusions CHIME Cosmology 21cm imaging survey for BAO to study Dark Energy Also sensitive to slow transients (30- sec integrations, revisit sky daily) Could have entire talk on this!! CHIME also great for fast radio transients, pulsars, ISM variability, First light expected mid- 2016 Canada Research Chairs Program, Lorne Trottier Chair in Astrophysics & Cosmology