Researchers are one step closer to identifying what lies beyond our galaxy thanks to the Canadian Hydrogen Intensity Mapping Experiment (CHIME).
Located in the Dominion Radio Astrophysical Observatory (DRAO) in Kaleden, CHIME is Canada’s largest radio telescope. Commissioned in 2017, it has already broken new ground in detecting fast radio bursts (FRB) originating 1.5 billion light years away.
“FRBs are fast burst of radio waves that appear to be coming from outside of our galaxy and they currently don’t have a firm explanation for them yet,” said Paul Scholz, research associate at DRAO and member of the CHIME FRB collaboration. “So they’re an open mystery in astrophysics right now.”
Over a three-week period in July and August 2018, CHIME recorded 13 FRBs, one of which was repeating. This is compared to the 50 that have been recorded over the past decade, one of which was also repeating.
Scholz explained that CHIME will “blow the field open” in the next few years because it can detect several FRBs per day.
“We found 13 of these in about a 3-week period this summer in a pre-commissioning phase of the telescope. So this is the iceberg of the results from CHIME,” said Scholz. “In regard to the first recorded repeating FRB, there was a question as to whether this was unique or how rare repeating sources were in the FRB population. So finding a second one means they are not super rare, but are fairly common.”
Prior to CHIME becoming operational, FRBs were only detected at wavelengths of approximately 800 megahertz. CHIME has the capacity to detect FRBs at wavelengths from 400 - 800 megahertz within the electromagnetic spectrum - meaning it has helped narrow down theories about these phenomena and the material around them.
Scholz said these FRBs are “coming from all directions in the sky” which means they are an object or phenomenon that is in a fairly common place in the universe. In addition, because their durations are short they can determine the object must be small because of the speed of the light.
“This means we’re left with dense energetic objects such as neutron stars or blackholes,” said Scholz. “Those are the lines that people are thinking along when coming up with explanations for FRBs.”
Because CHIME is able to detect several FRBs per day, Scholz said the research team will be able to build up a sample of hundreds of them for analysis, giving them a bigger picture as to what could be creating them.
“We’ll be able to transition from a regime where we know of a small amount of sources, so when we look at each individual one, we analyze them like individual snowflakes,” said Scholz. “With a large sample we can step back and analyze the whole population itself and answer questions like how much of the population is repeating, do they look like evolve, do their properties change as a function of cosmic time, things like that.”
Scholz’s responsibility with CHIME is to assist the software pipeline that detects and characterizes FRBs in real time. He explained because the amount of data collected per second by the telescope is so high, it can’t be all saved so the researchers must analyze it as it comes in to detect FRBs and determine whether it is interesting enough to save.
“I’m also involved in the follow-up analysis we perform when we detect exciting events,” said Scholz.
So what do FRBs have to do with the further examination of our galaxy and beyond? Scholz explained it has taken light billions of years to get here from whatever the source of these FRBs are.
“We’re of course very interested in figuring out what is causing FRBs, what exotic phenomenon is creating these energetic bursts. There’s also the promise of them being used as probes for the material between us and the source of the emission,” said Scholz. “We might be able to learn about the structure of our universe and the gas that populates the space between galaxies, which we have very few probes for currently.”
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