Author Topic: Active galaxies with ionized gas clouds - more denizens of the Zoo  (Read 135256 times)

NGC3314

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With the excitement about new observations of Hanny's Voorwerp, this might be a good time to point out that Zoo participants are finding new examples of a related (albeit less spectacular) class of objects. (That was evidently my roundabout way of saying "hey, everyone, you can look for these too!").

What do these four galaxies have in common?


NGC 5972


588017991773520114


587736809916399664


Mkn 266

First off, they all have active galactic nuclei (AGN) as revealed by the spectra. Second, and more unusual, the SDSS images all show oddly colored filaments or loops around the nucleus. (Kevin named that second one the Teacup because of the loop). Colors this pure don't come from starlight - and indeed, wherever we have the additional information to say, we find that these are ionized gas illuminated by the nucleus. (This should sound familiar to member of the Voorwerp Van Club). Seeing these giant emission-line clouds tells us about the environment of the AGN - how much gas is out there, what its density and ionization state are... It also tells us about the AGN, since the gas views it from various directions that we don't. Some AGN are partially surrounded by cods of absorbing material so that our view isn't necessarily representative.

What else do we know about these galaxies? NGC 5972 attracted some interest as possibly being a spiral with a giant double-lobed radio source, which would be quite rare. In a study published in 1995, Phillippe Veron and Mira Veron-Cetty showed that  the "spiral arms" are filaments of gas ionized by the central AGN, whose motions are mostly smooth rotation about the core.

Colleagues at Georgia State University kindly measured a spectrum for part of the handle of Kevin's Teacup, using the 1.8m Perkins telescope at Lowell Observatory. Same story - the gas is ionized by the copious UV and X-radiation of an AGN. The loop shape is interesting, spanning something like 15,000 light-years. Could this be a bubble driven by some kind of hot outflow from the core? Scribble, consult Chandra instrument guide...

Mkn 266 (AKA NGC 5256) is a picturesque merger with embedded AGN. Its emission-line features have received attention all the way back to 1988, with interpretations including gas shocked by collisions during the merger.

I'd be willing to bet that there are more of these hiding in the SDSS data. In the usual color mapping, strong [O III] emission shows up as blue and H-alpha as green at low redshifts. H-alpha shifts to the red (i) band at greater redshifts. The Teacup shows both [O III] and H-alpha, and at its redshift these add to purple.

Find another one? Feel free to chime in and share it here! Sharing common features but being much smaller, maybe we could call them voorwerpjes.

« Last Edit: April 23, 2009, 04:50:00 pm by NGC3314 »

Half65

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Re: Active galaxies with ionized gas clouds - more denizens of the Zoo
« Reply #1 on: April 21, 2009, 05:34:14 pm »
I believe another syndrome is coming.
Could be
Ionized ... Ionized ... Ionized ...  :D :D :D :D :D :D :D

NGC3314

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Re: Active galaxies with ionized gas clouds - more denizens of the Zoo
« Reply #2 on: April 21, 2009, 06:41:13 pm »
I'd hate to think I'm only a carrier.

Ioannab

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Re: Active galaxies with ionized gas clouds - more denizens of the Zoo
« Reply #3 on: April 21, 2009, 07:03:51 pm »
With a little trepidation (as I am still quite new at this game) I make the following offering: it has some nice emission lines, and hopefully fits the bill.  :) :) :)


http://cas.sdss.org/dr7/en/tools/quicklook/quickobj.asp?id=587739406784790531
"Nature herself has never attempted to effect great changes rapidly" - Quintilian

mitch

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Re: Active galaxies with ionized gas clouds - more denizens of the Zoo
« Reply #4 on: April 21, 2009, 11:11:57 pm »
http://cas.sdss.org/dr6/en/tools/quicklook/quickobj.asp?id=587739706873806988



I share Ionnab's trepidation and hope the purple is not caused by filters - it has high Ha and OII ....

Half65

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« Last Edit: April 23, 2009, 05:58:35 pm by Half65 »



Half65

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« Last Edit: April 23, 2009, 06:11:40 pm by Half65 »

Half65

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« Last Edit: April 23, 2009, 06:12:34 pm by Half65 »

stellar190

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Re: Active galaxies with ionized gas clouds - more denizens of the Zoo
« Reply #10 on: April 23, 2009, 04:24:52 pm »
I believe another syndrome is coming.
Could be
Ionized ... Ionized ... Ionized ...  :D :D :D :D :D :D :D

i think iv caught it :o ;D

*goes off to find galaxies with ionized stuff*

i love that galaxy with the pink gas

Half65

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« Last Edit: April 23, 2009, 06:13:39 pm by Half65 »

ElisabethB

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Re: Active galaxies with ionized gas clouds - more denizens of the Zoo
« Reply #12 on: April 23, 2009, 04:30:58 pm »
It's official : Half is suffering from another syndrome !  ;D

zookeeperKevin

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Re: Active galaxies with ionized gas clouds - more denizens of the Zoo
« Reply #13 on: April 23, 2009, 04:41:58 pm »
I'm stickying this as it's an exciting and important topic!

Half65

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Re: Active galaxies with ionized gas clouds - more denizens of the Zoo
« Reply #14 on: April 23, 2009, 04:43:48 pm »
It's official : Half is suffering from another syndrome !  ;D
I need to update my signature.  :D :D :D :D :D