Why Do Some Galaxies Have Warped Structures?

[Astronuc]

I was browsing sites on the galaxies in response to another thread, and I encountered a rather unusual picture of ESO 510-G13

Hubble Photographs Warped Galaxy as Camera Passes Milestone
http://hubblesite.org/newscenter/archive/releases/2001/23/

http://hubblesite.org/newscenter/archive/releases/2001/23/image/a/

http://apod.nasa.gov/apod/ap030607.html

http://www.eso.org/public/images/eso9924e/

The galactic plane is 'bent'. I'm curious as to the reason.

I was also interested in a comment about a 'recent' interaction with another galaxy. But how recent?

And another interesting comment - The Milky Way Galaxy is Warped - apparently somewhat like ESO 510-G13!
http://www.etnaastros.com/documents/MW_Warped_2-06.pdf

Are there other galaxies similarly warped?

 

[turbo]

Are there other galaxies similarly warped?

Lots of them. During the data-collection for our paper on interacting galaxies, we reviewed images of thousands of galaxies, and there are a lot of oddities - distortions created by gravitational interaction, mergers, ejection events, etc. In fact, distortions, tidal features and enhanced star formation are evidence for interaction rather than chance alignment of foreground and background galaxies.

If you will browse these two sites, you'll see a lot of oddities. These collections are hosted by CalTech, ironically part of the very consortium that stripped Arp of all his observing time because his study of interacting galaxies was politically unpopular with members of the observing-time allocation committee.

http://nedwww.ipac.caltech.edu/level5/Arp/frames.html
http://nedwww.ipac.caltech.edu/level5/SPGA_Atlas/frames.html

There are lots of oddities in major catalogs as well, but Arp and Arp-Madore did a nice job isolating oddities and highlighting them by type. Follow-up spectroscopy on many of the "obviously" interacting pairs turned up anomalous redshifts, and the inviolability of the Hubble redshift-distance relationship prevented (and still prevents) mainstream cosmologists from considering them to be interacting bodies instead of chance projections.

 

[Astronuc]

Lots of them. During the data-collection for our paper on interacting galaxies, we reviewed images of thousands of galaxies, and there are a lot of oddities - distortions created by gravitational interaction, mergers, ejection events, etc. In fact, distortions, tidal features and enhanced star formation are evidence for interaction rather than chance alignment of foreground and background galaxies.

I was wondering more about warped galaxies in which there are no apparent 'near-by' neighbors (clearly galaxies interact significantly when close enough). I couldn't tell from the images of ESO 510-G13 if there was a neighboring galaxy near enough to interact.

The Milky Way have a few neighbors. In the cited pdf, it mentions the SMC and LMC, but not the closer ones - Canis Major Dwarf and Sagittarius Dwarf Sphr - but perhaps they lack sufficient mass to be significant.


Ah - I found a bit more information - http://heritage.stsci.edu/2001/23/supplemental.html

. . . . Galaxies that look like ESO 510-G13 are very rare in the nearby universe. . . .

In the nearby universe galaxy interactions are spectacular, but rare. Less than 5% of galaxies are currently undergoing a strong interaction with another galaxy of similar mass. In the distant universe we see many more galaxies undergoing interactions, with perhaps as many as half involved in what are called major mergers where two galaxies merge together to form a new galaxy. It is now thought that most galaxies we see today originated from this merging process.

ESO 510-G13 is unique in that several scenarios could be responsible for producing it's structure. The warped disk could result from a fly-by encounter of a galaxy, or, a more interesting possibility, the warped disk itself is the remains of a galaxy captured by ESO 510-G13 in the past.

Small disk warps around galaxies are not uncommon however, and most galaxies show some form of a warp when viewed in the distribution of their internal hydrogen gas. Stellar warps, like the one seen in ESO 510-G13, are not as common, but small stellar warps are seen in several other galaxies. Our nearest large neighbor, the spiral galaxy M31, also has a warped stellar disk, probably the result of an interaction with the Milky Way.

. . .

Note the DSS image of ESO 510-G13

turbo - thanks for the links. I also found an article on Lopsided Spiral Galaxies
http://nedwww.ipac.caltech.edu/level5/Sept09/Jog/frames.html

 

[turbo]

Galaxies like the one in the OP may not be as rare as stated in the above link. Part of the rarity factor is that such a galaxy needs to be edge-on or nearly so for us to see the warped outer regions. If that galaxy was face-on or nearly so it could be impossible to discern a warp. We can't go zooming around there, so we have to take what we see.

 

[turbo]

I was wondering more about warped galaxies in which there are no apparent 'near-by' neighbors (clearly galaxies interact significantly when close enough). I couldn't tell from the images of ESO 510-G13 if there was a neighboring galaxy near enough to interact.

If the neighbor is on the far side of that galaxy, it might be blocked from our view, so we can't identify the body that caused the warp. For instance, we don't know to what extent M51's companion has warped its disk because the system is practically face-on. We know that there has been significant gravitational interaction though, from studying the outer environs of the host and the extended halo and tails of the companion. If we were to see M51 and it's companion edge-on with the companion occluded by the host, I wouldn't be a bit surprised to see some significant warping.

 

[Chronos]

The disturbance may have occurred billions of years ago. The interacting object may have been obsorbed, passed right through or some combination thereof. The milky way rotates once every ~250 million years. How many rotations would it take to gravitationaly smooth out a bump in the disc?