What will our galaxy look like in radio+IR?
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Milkybear
Looking at these images makes me wonder.
Presumably we cannot image the milky way until we can travel outside of it, but do we know what it would look like?Posted
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KWillett
scientist, admin, translator
That's a fantastic question, @Milkybear. You're quite right - we really don't know for sure without having that "birds-eye" view that we do of other galaxies. However, we can look at nearby spiral galaxies and presume they're pretty similar to the Milky Way.
One of the most important differences is in the state of the radio jets; as we've talked about a lot, the jets you see in RGZ are ionized plasma powered by the magnetic field of material falling in near the central black hole. We do know that the Milky Way has a black hole - its name is Sgr A* (pronounced Sadge A-star), located about 8400 parsecs from the Sun. However, our black hole - unlike most of these galaxies - is NOT in an active state. Rather, it's what we call passive or quiescent - there's not enough material falling near the black hole to produce these spectacular jets.
So in an RGZ image, there likely wouldn't be any emission from an extended jet. Depending on the sensitivity and distance of your telescope, you'd see some compact radio emission that comes from the supernovae and HII regions in the Milky Way; and if you were close enough, you'd be able to see that the radio emission tended to trace the spiral arms and the disk. What you wouldn't see is a bright source at the core, nor the big jets stretching out way beyond the disk as you do for many RGZ galaxies.
The IPAC "Cool Cosmos" site has a nice multiwavelength view of M101, a nearby spiral galaxy, which gives a great visual picture of this. The near-infrared and radio views are what you'd be likely to see. http://coolcosmos.ipac.caltech.edu/cosmic_classroom/multiwavelength_astronomy/multiwavelength_museum/m101.html
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Milkybear
Thank you for the explanation and link 😃
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