#Astrophysics incoming!
My very capable former colleague here in Stockholm, who is not on this platform, has made a very interesting discovery over the last couple of years, and has a press release out about it today.
She has been studying a galaxy that a lot of us in Stockholm have spent a lot of time studying, including myself. But where most of us have studied it in normal light, Alexandra has looked at it in 21cm. radio waves... 1/n
#Astrophysics incoming!
These 21 cm waves trace cold, neutral Hydrogen gas which wraps around every galaxy in the Universe, but is almost impossible to see in any other kinds of radiation.
Unfortunately, this 21 cm radiation is also very faint and very difficult to see at large distances. With her work, Alexandra has pushed the record for largest distance of a 21 cm image, by a significant margin. 2/n
#Astrophysics incoming!
The galaxy, called Haro 11, is interesting for many reasons. It is the result of a collision of at least two smaller galaxies, which has messed up its shape a lot, and sparked intense star formation. Simply put, it contains many different types of galaxy environment wrapped in one package.
My personal interest in it is that it is one of very few galaxies in the present-day universe which emits a certain kind of extreme-UV radiation 3/
#Astrophysics incoming!
This extreme UV radiation is absorbed by the envelope of cold gas that surrounds all galaxies, and a lot of my research is centered around trying to find out how this extreme-UV radiation gets through this cold hydrogen envelope and out into intergalactic Space. *Something* must be at least partially clearing away this gas so the EUV light can get out. Alexandras work now seems to have given a possible, and quite compelling, answer!
#Astrophysics incoming!
Here's her image! The white light is from stars in the galaxy, the diffuse red light is from hot ionized Hydrogen, and the blue color shows the extent of the 21 cm emission of the gold, neutral gas.
You see something weird? We expected the cold gas to be sitting as an envelope surrounding the main galaxy - that is how it usually works. But it is almost completely absent there! Instead, huge amounts of cold gas is trailing after the galaxy like the tail of a tadpole. 4/n
This so-called *tidal stripping* of the cold gas is most likely result of the merger itself or a gravitational interaction with another galaxy in the not too distant future. Its gravity will simply have pulled enough at this cold gas that it has been partially removed from the galaxy and dragged into this large tail (which is a good deal larger than we can see in the picture, by the way).
This would be an effective way of opening up gaps in the gas for the extreme-UV light to escape. 6/n
@tobychev Yeah that was a brain fart, I have corrected it now. Thanks, edit button!