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The Question
(Submitted January 16, 1998)
I don't know very much about astronomy but I have to do I paper on it for
school. I was very confused at your info on Blazars. I would like a simple
answer to: What are blazers? Thanks!
The Answer
This is a good question, and it might be good to divide it
up into 2 parts: first, what does a blazar look like to astronomers,
and second, what is actually going on in a blazar?
It turns out that astronomers themselves can't even answer the
first question with certainty. I would say that in order to be called
a blazar, an object must have the following characteristics:
1) It must appear point-like on the sky, i.e. not appear fuzzy like
a galaxy or a nebula. Some blazars have nebulae around them, but most of
the light comes from a point source.
2) Their spectra appear to be smooth (i.e. no strong absorption lines
that a star might have) and flatter than a star. These 2 properties by
themselves would make them a quasar.
3) Their visible light is often partially polarized.
4) Their output in all wavelength bands varies more rapidly and by a larger
amount than a quasar.
Now, what is going on? As the website says, possibly a jet of material
coming from near a black hole, with the gas in the jet moving very nearly
the speed of light and coming nearly straight toward us.
I hope this helps,
Tim Kallman
for the Ask a High-Energy Astronomer team
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