The Canadian Hydrogen Intensity Mapping Experiment (CHIME): Status and update. Juan Mena-Parra MIT Kavli Postdoctoral Fellow October 30, 2018

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1 The Canadian Hydrogen Intensity Mapping Experiment (CHIME): Status and update Juan Mena-Parra MIT Kavli Postdoctoral Fellow October 30, 2018

2 The CHIME telescope CHIME is an interferometer radio telescope designed to: Measure the expansion history of the universe to learn about dark energy Study Fast Radio Bursts (FRBs) and pulsars Dominion Radio Astrophysical Observatory, BC, Canada

3 CHIME design Four 20m x 100m cylindrical reflectors 1024 broadband dual-polarization antennas sensitive to MHz Field of view: ~90 degrees NS by degrees EW Synthesized beam size: arcminutes Full CHIME Feeds along focal line of one of the cylinders CHIME pathfinder

4 Field of view and scan strategy CHIME observes the sky as it transits through its field of view We map the northern half of the sky every day Each feed sees a N-S stripe of the sky Feeds on each cylinder sample the sky along the N-S stripe The E-W array of cylinders provide resolution in the EW direction

5 The CHIME receiver 2048 analog receivers Receiver noise temperature: below 50 K Analog sampling: 800 MSPS, 8 bits Frequency resolution: 390 khz, 1024 channels Deng et al Bandura et al Bandura et al. 2016

6 The CHIME correlator FX architecture Processes 2048 inputs over 400 MHz of bandwidth Massive data rate: 13.1 Tbit/s raw input 6.6 Tbit/s F-engine internal networking 840 trillion complex operations per second Separate real-time backends for: Cosmology FRB search Pulsar timing Recnik et al Klages et al Denman et al Bandura et al CHIME/FRB Collaboration 2018

7 Backends Cosmology Full N² visibility matrix 10 s cadence Raw output: 210 TB/day Real time flagging and gain calibration 1 TB/day after data compression FRB search 1024 stationary beams 1 ms cadence 16k frequency channels Pulsar timing 10 steerable beams 2.56 μs cadence Lorimer et al. 2007

8 Status First light ceremony on September 7, 2017 Began collecting science data on March, 2018 Implemented flagging and calibration in real-time N² data is compressed over redundant baselines prior to long-term archiving We also save full N² data for 4 frequency channels for development of flagging, compression and calibration algorithms Credit: Seth Siegel

9 FRBs with CHIME 13 FRBs detected during pre-commissioning phase We were not yet at final design specification Telescope characterization in progress Not all beams were being processed Varying frequency coverage Calibration strategies being tested FRBs observed to frequencies down to 400 MHz (ATEL #11901) Most FRBs show scattering, some appear unscattered even at lowest frequencies One FRB has the lowest DM yet reported (109 pc/cc) One repeater CHIME/FRB Collaboration, Nature, submitted

10 A second repeating FRB RA, Dec = 63 (4h 22m), +73 High Declination. Falls within the primary beam twice per day DM = pc/cc Galaxy contribution ~ pc/cc DM excess ~ pc/cc (z <~ 0.1) About half the distance to the first repeater (Spitler et al. 2016) Some events exhibit multiple spectro-temporal structures, reminiscent of bursts from R1 Suggests there exists a substantial population of repeating FRBs CHIME/FRB Collaboration, Nature, submitted

11 Summary CHIME will measure the expansion history of the universe and study the nature of dark energy It will also study pulsars, FRBs, and other transient radio phenomena It is already detecting FRBs (including a second repeater) CHIME is operational and collecting early science data There is an ongoing effort to characterize the instrument to the level required to reach the science goals

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