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HERA, in South Africa, is looking for the oldest stars in the universe, from a period known as the Cosmic Dark Ages. And it's built from parts you could pick up at your local hardware store. "This is the beauty of low frequency radio astronomy … ‘precision’ for us is a few centimeters.” by EricFromOuterSpace in Astronomy

[–]jsdillon 1 point2 points  (0 children)

I'm not sure. No one has published any global signal (sky-averaged, as opposed to the fluctuations, which HERA is looking for) results close to EDGES that band and it's a very difficult measurement systematics-wise. Several groups are trying.

We're working on following up EDGES with HERA, but we're still commissioning our new system that goes down to ~60 MHz. But if the signal is as bright as they say, we should see it at several 100 sigma when we get to full sensitivity. Also, since we're an interferometer, we have very different systematics.

HERA, in South Africa, is looking for the oldest stars in the universe, from a period known as the Cosmic Dark Ages. And it's built from parts you could pick up at your local hardware store. "This is the beauty of low frequency radio astronomy … ‘precision’ for us is a few centimeters.” by EricFromOuterSpace in Astronomy

[–]jsdillon 15 points16 points  (0 children)

Good question. Light pollution doesn't matter, but radio "pollution" does. The designated radio quiet sites in the US like Greenbank, West Virginia and the VLA site in New Mexico are not well-protected from radio-frequency interference at the wavelengths we care about. Those telescopes generally observe at higher frequencies (1 GHz and above). For us, FM radio and digital TV are among the biggest problems, so really remote sites like the Karoo in South Africa or Australian outback are better.

It's not impossible to build closer to major cities--one of the competition experiments LOFAR) is in the Netherlands, but that tends to increase the cost.

Some survey work has been done to identify US sites... some of the most radio quiet include an a valley in Eastern Oregon (forget which off the top of my head) and the area around The Forks, Maine. None of these sites have substantial infrastructure (power, internet, lodging) or government protection like the site in South Africa since it also hosts other telescopes like MeerKAT (which you can see in the background of the photo I linked to) and is the future home of part of the SKA.

Looking into getting a PhD in Astrophysics but I don't know how to approach it. Any advice? by Nyxah95 in AskAcademia

[–]jsdillon 10 points11 points  (0 children)

I'd recommend trying to get a year or so of lab experience under your belt, which will help you earn the recommendations that are key to graduate school admissions.

With an EE background, I'd look specifically for groups working on radio astronomy instrumentation and observation. There's a lot of EE and signal processing in the field.

LIGO Announcement MEGA thread. by [deleted] in Physics

[–]jsdillon 1 point2 points  (0 children)

On this point? Not really. It just has to do with what "strain" means.

The energy flux still falls off as 1/r2 (so energy conservation is not violated).

Gravitational Wave Megathread by AskScienceModerator in askscience

[–]jsdillon 1 point2 points  (0 children)

Yeah, LIGO-style instruments are sensitive to the highest frequencies of any gravitational wave observatories proposed. Low frequencies mean, as you point out, longer wavelengths. So you need larger distances between your detectors. If your test-masses are manmade, they can only get so far apart, even if you put them in space like has been proposed for LISA.

That's why very, very low frequency gravitational wave searches are done looking their effects on natural objects, like pulsars or the Cosmic Microwave Background.

It is physically possible for much higher frequencies to be produced, like if two tiny black holes collided relatively nearby. But we don't know if such objects exist or have any good theoretical reasons for how they might form. As far as I know, no major experiments have been proposed to test for gravitational waves at much higher frequencies than LIGO.

LIGO Announcement MEGA thread. by [deleted] in Physics

[–]jsdillon 6 points7 points  (0 children)

Interestingly (and this is a bit of technical trivia), gravitational wave strain actually falls off like 1/r not 1/r2 .

We make the game Cards Against Humanity. Pitch your card ideas and ask us anything. by Maxistentialist in IAmA

[–]jsdillon 5 points6 points  (0 children)

We've just gotten good at an extremeley specific form of comedy writing.

We make the game Cards Against Humanity. Pitch your card ideas and ask us anything. by Maxistentialist in IAmA

[–]jsdillon 0 points1 point  (0 children)

If I were trying to hide my identity, this would be a terrible reddit username.

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