Quasar spectra

Where is a good place to find out about the specta of quasars, if
any?

David A. Smith

"N:dlzc D:aol T:com (dlzc)" wrote in message
...
: Where is a good place to find out about the specta of quasars, if
: any?
:
: David A. Smith
:
:
The sky. You might need some hefty and expensive equipment, though.

N:dlzc D:aol T:com (dlzc) wrote:
Where is a good place to find out about the specta of quasars, if
any?

What exactly are you looking for? There are probably hundreds of
spectra published (mostly in the 1980's, I'd guess) and thousands
available from various data centers.

A quick search in ADS doesn't turn up a review article. I'm surprised
by that. Probably my bad choice of keywords is bad; I can hardly
believe there isn't a good review.

Dear Steve Willner:

On Jul 16, 2:16 pm, Steve Willner wrote:
N:dlzcD:aol T:com (dlzc) wrote:

Where is a good place to find out about the specta
of quasars, if any?

What exactly are you looking for? There are probably
hundreds of spectra published (mostly in the 1980's,
I'd guess) and thousands available from various data
centers.

I had a "wild hair" that quasars might be regions of "oscillating
spacetime" (like a float bobbing up and down in a lake), but the
description he
http://www.astronomynotes.com/galaxy/s12.htm
QUOTE
Quasars have a decidedly non-thermal spectrum...
END QUOTE
.... puts an end to my fancy.

A quick search in ADS doesn't turn up a review article.
I'm surprised by that. Probably my bad choice of
keywords is bad; I can hardly believe there isn't a good
review.

I found enough to answer my immediate need. Thank you for the
response!

David A. Smith

dlzc wrote:
http://www.astronomynotes.com/galaxy/s12.htm
QUOTE
Quasars have a decidedly non-thermal spectrum...

Sounds like what you wanted is what we call a "spectral energy
distribution" (SED): the amount of energy emitted as a function of
wavelength across a broad wavelength range but without high spectral
resolution.

As the source says, quasars have a very broad SED, covering many
decades of the electromagnetic spectrum from radio to X-rays. (For
careful writers, "quasar" = quasi-stellar _radio_ source. The more
general term quasi-stellar _object_ or QSO includes both radio-loud
and radio-quiet objects.)

There are lots of sources of SEDs, but one standard one is Elvis et
al. (1994 ApJS 95, 1). Try
http://adsabs.harvard.edu/cgi-bin/np...k_type=ARTICLE
for a copy.

Dear Steve Willner:

"Steve Willner" wrote in message
oups.com...

dlzc wrote:
http://www.astronomynotes.com/galaxy/s12.htm
QUOTE
Quasars have a decidedly non-thermal spectrum...

Sounds like what you wanted is what we call a "spectral
energy distribution" (SED): the amount of energy emitted
as a function of wavelength across a broad wavelength
range but without high spectral resolution.

As the source says, quasars have a very broad SED,
covering many decades of the electromagnetic spectrum
from radio to X-rays. (For careful writers, "quasar" =
quasi-stellar _radio_ source. The more general term
quasi-stellar _object_ or QSO includes both radio-loud
and radio-quiet objects.)

There are lots of sources of SEDs, but one standard
one is Elvis et al. (1994 ApJS 95, 1). Try
http://adsabs.harvard.edu/cgi-bin/np...k_type=ARTICLE
for a copy.

Home run! Many thanks.

Have you heard any explanation for the "gap" between the UV and
the few more energetic data points? Absorption perhaps?

David A. Smith

SW There are lots of sources of [QSO] SEDs, but one standard
SW one is Elvis et al. (1994 ApJS 95, 1). Try

N:dlzc D:aol T:com (dlzc) wrote:
Have you heard any explanation for the "gap" between the UV and
the few more energetic data points? Absorption perhaps?

Yep. That's the "extreme ultraviolet" range, where neutral hydrogen
is a strong absorber.