Mapping the cosmos with hydrogen?

[PB666]

http://astronomynow.com/2015/09/20/mysterious-energy-bursts-provide-new-way-to-chart-the-cosmos-in-3-d/

[Steel]

Mapping the universe with hydrogen is certainly no new thing, 21 cm radiation has been a big part of astronomy for a while now.

However, this seems pretty novel. I'll dig into the paper a bit later to see what it's actually about, you can never take news articles - even scientific ones - at face value.

[YNM]

Yeah, only the method for distance that's novel. They should be wary for the sources of there bursts, because AFAIK different sources have different signatures, just like how slow GRB differs with "standard" GRB and with fast GRB, and even we are not what are the source of each (just one event) of them. Also, I don't think intergalactic space have much effect on c at different wavelength...

[PB666]

Yeah, only the method for distance that's novel. They should be wary for the sources of there bursts, because AFAIK different sources have different signatures, just like how slow GRB differs with "standard" GRB and with fast GRB, and even we are not what are the source of each (just one event) of them. Also, I don't think intergalactic space have much effect on c at different wavelength...

Are they simultaneously mapping distance and relative velocity, how exactly are they doing this.

[YNM]

Are they simultaneously mapping distance and relative velocity, how exactly are they doing this.

They are only mapping position and not velocity.

This is quite well-known for other standard candles (which often ends up at visible wavelength because past datas are mostly in visible), for example SN Ia (even before we start to realize there're two kinds of SN Ia there's a way to compensate for difference in maxima ratios) or Cepheids type I and RR Lyrae. Their objects are quite novel, and they should be concerned of what caused it before going on to make it standard candles.

Mapping velocity is done through spectrograph, and AFAIK that's the only way to do it.