Scientists track down the source of mysterious radio bursts(washingtonpost.com)
washingtonpost.com
Scientists track down the source of mysterious radio bursts
https://www.washingtonpost.com/news/speaking-of-science/wp/2016/02/25/scientists-finally-track-down-the-source-of-mysterious-radio-bursts/
28 comments
One of my favourite stories about mysterious signals also involves the Parkes radio telescope: some of the signals detected during this 'fast radio burst' search came from people opening a microwave's door without first waiting for the heating cycle to complete: http://www.abc.net.au/news/2015-05-05/scientists-discover-si...
That's what I thought too, and before reading the article, I guessed "it's a microwave again".
I wouldn't say they've tracked down the "source", merely the location of the source. Still, I really enjoyed learning a bit about how they managed to organize quick notifications to point a bunch of telescopes at a fleeting event.
And only a single FRB source at that. These only happen a few times a year, and this is the first time they were able to pin down the source. It will be much more interesting once we know the pattern of the sources (assuming there is one).
> Scientists believe they must occur thousands of times a day, but until this most recent study, only 16 had ever been detected. They seem randomly distributed throughout the sky, and no one is sure what causes them.
They are said to happen more frequently than a few times a year. I'm guessing it's just that we are not detecting the bulk of them because they're randomly distributed.
They are said to happen more frequently than a few times a year. I'm guessing it's just that we are not detecting the bulk of them because they're randomly distributed.
And they haven't even tracked down the location of the source as well as it sounds. They detected a burst, and found a fading radio source in that field of view, but there's a decent chance (<6% or <0.1%, depending on which of their estimates you prefer) that it's just coincidence.
Alas, if it's just coincidence, the rest of the (beautiful!) paper falls apart.
Alas, if it's just coincidence, the rest of the (beautiful!) paper falls apart.
What happens if someone has scheduled time with the telescope. Do they get bumped? Who has priority?
> What happens if someone has scheduled time with the telescope. Do they get bumped? Who has priority?
Yes they generally get bumped and they will generally get that time back later on in the telescope schedule. Folks who do these "target of opportunity" proposals apply like usual, but don't specify targets. If awarded time, they get the ability to "trigger" their observations once an interesting target appears. So their time allocation is (generally) capped like everyone else's, but isn't scheduled. So presumably the people who get bumped will have their observations rescheduled for later.
In detail the question of priority is a bit more complicated, and sometimes the people observing can refuse to be bumped for a TOO, but that varies with the observatory and their rules.
Edit: Also, people are frequently happy to even "donate" a little bit of their telesocpe time to observe interesting transient sources (sometimes in exchange for co-authorship or acknowledgements in papers, sometimes not). This is partly because astronomy is a reasonably friendly field. And it's also because we can't design and carry out experiments like other fields of science – we have to take what the Universe gives us. So it's good to take advantage of opportunities to view interesting and new sources when they happen.
Yes they generally get bumped and they will generally get that time back later on in the telescope schedule. Folks who do these "target of opportunity" proposals apply like usual, but don't specify targets. If awarded time, they get the ability to "trigger" their observations once an interesting target appears. So their time allocation is (generally) capped like everyone else's, but isn't scheduled. So presumably the people who get bumped will have their observations rescheduled for later.
In detail the question of priority is a bit more complicated, and sometimes the people observing can refuse to be bumped for a TOO, but that varies with the observatory and their rules.
Edit: Also, people are frequently happy to even "donate" a little bit of their telesocpe time to observe interesting transient sources (sometimes in exchange for co-authorship or acknowledgements in papers, sometimes not). This is partly because astronomy is a reasonably friendly field. And it's also because we can't design and carry out experiments like other fields of science – we have to take what the Universe gives us. So it's good to take advantage of opportunities to view interesting and new sources when they happen.
Usually when applying for time on a large telescope there are a few different categories of time. Most ordinary observations don't have to be done at any particular time and many of the larger observatories use queue observing for these targets. There's just a big list of these targets and the observer goes down the list and observes them one by one.
You can also apply for a "target of opportunity" when you don't know exactly when or where the event will take place, but there is a good chance that some event will occur over the next observing cycle. If you execute on a target of opportunity you jump to the front of the queue. If there's a particularly high time sensitivity (like for an FRB) then you might even interrupt an ongoing observation.
Things are trickier at a smaller observatory because they generally don't use queue observing. What happens instead is that an astronomer is granted some number of nights and they have the whole telescope for that amount of time. All you can do then is call them up and ask nicely. Usually they will though because they get on a paper without too much work. (The most highly cited paper I'm on happened that way!)
You can also apply for a "target of opportunity" when you don't know exactly when or where the event will take place, but there is a good chance that some event will occur over the next observing cycle. If you execute on a target of opportunity you jump to the front of the queue. If there's a particularly high time sensitivity (like for an FRB) then you might even interrupt an ongoing observation.
Things are trickier at a smaller observatory because they generally don't use queue observing. What happens instead is that an astronomer is granted some number of nights and they have the whole telescope for that amount of time. All you can do then is call them up and ask nicely. Usually they will though because they get on a paper without too much work. (The most highly cited paper I'm on happened that way!)
You get to stare at the stars all night? How wonderful!
I used to! But permanent jobs are hard to come by in astronomy so I have since moved on to work in the medical technology industry.
I didn't realize you had left the field. Sorry to hear that. Dunno if you remember, but we observed together at the LBT a while back, for one of the MODS runs. I've enjoying seeing you and your comments around HN – you give quite good and thorough explanations.
Small world! You were at Virginia then, right? I'm glad you enjoyed my comments! I still feel like I haven't totally left the field yet since I just graduated in December and I've been working on finishing up a few projects in my spare time.
Yep! I was UVa until I defended in mid-2014. Since then I have been a postdoc in Chile.
Best of luck finishing up the astro projects. And have fun in the medical tech area – seems like there's lots of exciting things happening there!
Best of luck finishing up the astro projects. And have fun in the medical tech area – seems like there's lots of exciting things happening there!
Here's a link to the Caltech (which runs Palomar and Keck) ToO policy:
http://www.astro.caltech.edu/observatories/coo/TOO/ToOpolicy...
You can ask for ToO time (http://www.astro.caltech.edu/observatories/coo/solicit/2016A...), but it has to be approved as part of the semi-annual solicitation for observing time. When you use it, you have to notify the PI you bumped and a committee, and later report back to them on the results.
Postdocs don't have to give up their observing for a ToO, but faculty do.
In Caltech's policy, interrupted observers don't get payback time.
http://www.astro.caltech.edu/observatories/coo/TOO/ToOpolicy...
You can ask for ToO time (http://www.astro.caltech.edu/observatories/coo/solicit/2016A...), but it has to be approved as part of the semi-annual solicitation for observing time. When you use it, you have to notify the PI you bumped and a committee, and later report back to them on the results.
Postdocs don't have to give up their observing for a ToO, but faculty do.
In Caltech's policy, interrupted observers don't get payback time.
You confuse "source" and "cause".
It has been suggested that some if not most elliptical galaxies are the result of two similarly sized spiral galaxies colliding: http://spacetelescope.org/images/potw1148a/
The most energetic event I can think of would be two galactic core sized black holes colliding. Has this been ruled out already as a possible cause of FRBs?
The most energetic event I can think of would be two galactic core sized black holes colliding. Has this been ruled out already as a possible cause of FRBs?
Yes. The timescale of FRBs is too short to be caused by mergers of supermassive black holes. In general the source of an event cannot be any larger than the time for light to cross the source. In the case of a supermassive black hole binary the light crossing time is of order seconds to minutes, but FRBs last for only a few milliseconds. This limits them to be the size of neutron stars or smaller.
The accretion disks around black holes merging could act like a really massive and short lived particle accelerator. However, that's more likely to spit out a few Oh-My-God particle's than just a radio burst.
I think they buried the lede here! By combining the ability to determine dispersion in the signal path and now pinpointing the source, they recalculated the percentage of matter vs dark matter.
Dark matter makes up 95% of the universe now?!? As the article states, this is indeed mind boggling. We're missing a BIG piece of our understanding about the nature of the universe itself.
Dark matter makes up 95% of the universe now?!? As the article states, this is indeed mind boggling. We're missing a BIG piece of our understanding about the nature of the universe itself.
I think you misunderstood. 95% of the universe is not-ordinary-matter, which is split between 70% dark energy and 25% dark matter. _This model has been widely held for years._
This same model suggests that there should be 5% ordinary matter, but until now we have only observed half of that 5%. This new FMB observation shows the full 5% for the first time, bringing our observed data to better alignment with the model.
This same model suggests that there should be 5% ordinary matter, but until now we have only observed half of that 5%. This new FMB observation shows the full 5% for the first time, bringing our observed data to better alignment with the model.
> Dark matter makes up 95% of the universe now?!?
The article was very poorly worded. As @infogulch noted, the 5% is of the total energy content of the universe, not the "matter" content. So that's been known.
But what seems to be new is that of that 5% of normal (baryonic) matter, we've only been able to account for about half of it (stars, gas in galaxies). These FRB observations claim to have found evidence for the other half of the "missing baryons", likely in hot gas between galaxies.
The article was very poorly worded. As @infogulch noted, the 5% is of the total energy content of the universe, not the "matter" content. So that's been known.
But what seems to be new is that of that 5% of normal (baryonic) matter, we've only been able to account for about half of it (stars, gas in galaxies). These FRB observations claim to have found evidence for the other half of the "missing baryons", likely in hot gas between galaxies.
It is mind boggling, but it isn't new. The article is saying that these researchers were able to confirm the 5% estimate with a direct measurement.
Here's a book from 2011 on the subject: http://www.amazon.com/The-Percent-Universe-Discover-Reality/...
Here's a book from 2011 on the subject: http://www.amazon.com/The-Percent-Universe-Discover-Reality/...
Would older, elliptical galaxy be less hospitable to life? Or would it not matter? Would there be more GRB's and various other conditions that would decrease the likelihood of life? Just curious.
According to the article, supernovas occur more frequently in younger galaxies, and we know these can blow a star's heliosphere away temporarily exposing all its planets to deadly radiation (which it seems has happened to Earth before).
Also, stars that are large enough to experience a supernova have shorter lifespans than our Sun, giving less time for life to develop.
The article is good, but am I the only person who noticed the bizarre poll that's slapped into the middle of it?
no, no they didn't
"We still don't know what causes FRBs"
"but it's possible [...] that FRBs come from a VARIETY of sources"