A galaxy that has never merged

[echo-lily-mai]

As I was looking at BP’s photos I saw this one and I thought I might post it over here.



I don’t know which galaxy this is, do you?

I wanted to post this in complete contrast of a galaxy merging. It is thought that a galaxy like this may never in its history encountered another galaxy, not even as a fly by.

This galaxy has no bulge.

Zookeeper Chris (it may have been Kevin as well) was talking about these galaxies at our Oxford Zoo meet-up 28/04/12

I’m hoping to find more out about these. If anymore info gets posted or blogs get written I will add them to this thread. If these are being collected on the forum somewhere a link to them can simply be added here too.

Sorry, I know this has nothing to do with Merger Zoo, but strangely I believe it needs a mention here.   

[Alice]

I wrote it down and am hoping to get at it on the database somewhere for an OOTD

It's NGC 4395, if I wrote it correctly.

[echo-lily-mai]

That's ace Alice!!!!! I really look forward to that OOTD 

[zutopian]

It was an OOTD by Alice in 2008:
http://www.galaxyzooforum.org/index.php?topic=272239.msg172819#msg172819

[Alice]

I had completely forgotten that! Also, according to that picture, I'd say that one does have a bulge, even if it is mostly clumpy . . .

[zutopian]

Here is a new paper about possibly a similiar galaxy (NGC 4178) and they mention NGC 4395:

"The Chandra View of NGC 4178: The Lowest Mass Black Hole in a Bulgeless Disk Galaxy ?"

To date, there are only three such bulgeless disk galaxies that are confirmed to host SMBHs: NGC 4395 (Filippenko & Ho 2003; Shih et al. 2003;Peterson et al. 2005), NGC 1042 (Shields et al. 2008), and NGC 3621 (Satyapal et al. 2007; Barth et al. 2009; Gliozzi et al. 2009; Satyapal et al. 2009).

Authors: Nathan Secrest, Shobita Satyapal, Mario Gliozzi, Teddy Cheung, Anil Seth, Torsten Boeker
(Submitted on 1 May 2012)
http://arxiv.org/abs/1205.0230

I ask for an OOTD about those galaxies!

[echo-lily-mai]

That's great zutopian!

Here is the quote from Alice's notes from the Oxford meet-up

NGC 4395, which Echo and Zutopian put here This is a bulgeless galaxy. (Is it? Looks like it has one to me, albeit a small one.) Having no bulge means that it has never undergone a merger. This galaxy can be used to find out what galaxies do when they are left alone. For example: are black holes built up through mergers? This one's black hole size is a factor of 100 less than that of the Milky Way. (I assume this has been adjusted for size? This is especially interesting because I read somewhere that all galaxies possess a black hole of about 1% of their total mass at their centre. So am I right in thinking this galaxy's central black hole is only 0.01% of its total mass?)

The team are therefore checking bulgeless galaxies, especially looking at their emission lines. Are they actively growing an AGN? We find a few AGN, unexpectedly. The AGN is a point source; the bulge is a larger area. Those "fake AGN" cause people to say the galaxy has a larger bulge. So they're doing some simulations to remove the AGN and disk, which leaves the spiral arms and bulge. If there is generally a bulge present, the hypothesis is rejected. But many of these clumpy, never-merging galaxies do have tiny bulges. Some demonstrate that galaxies can grow their own AGN without ever having merged.

On a separate little note, nothing to do with bulgeless galaxies. I thought this was interesting too

The odds of a galaxy being a red spiral get higher in clusters, but other properties are not affected. That means that the mechanism for turning a galaxy red depend on the local environment. If interaction, for example, depended on the local area, we woulid see this happening. It is likely that red spirals are near-mergers - the flyby has removed their gas.

I hope even when our lovely Merger Zoo project has finished that there will be further merger related projects to work on.

[zookeeperChris]

One of the problems is that galaxies quite often have star clusters at their centre, which can look a little like small bulges - that's probably what's going on here. Hence the need for careful modelling...

Chris

[Blackprojects]

As I was looking at BP’s photos I saw this one and I thought I might post it over here.



I don’t know which galaxy this is, do you?

I wanted to post this in complete contrast of a galaxy merging. It is thought that a galaxy like this may never in its history encountered another galaxy, not even as a fly by.

This galaxy has no bulge.

Zookeeper Chris (it may have been Kevin as well) was talking about these galaxies at our Oxford Zoo meet-up 28/04/12

I’m hoping to find more out about these. If anymore info gets posted or blogs get written I will add them to this thread. If these are being collected on the forum somewhere a link to them can simply be added here too.

Sorry, I know this has nothing to do with Merger Zoo, but strangely I believe it needs a mention here.   

I Think i have a High res version of said Photo
Link only due to Size!

http://img.photobucket.com/albums/v402/markredgwell/GALAXYZOO%20OXFORD%202012/GalaxywithnoCore.jpg?t=1336265166

[zutopian]

There is a new blog post:

"Galaxy Zoo at the European Week of Astronomy and Space Science"

Brooke Simmons (now settling in as a new postdoc at Oxford after finishing her PhD at Yale recently) had a poster on some work I’m sure you’ll hear about soon about some very interesting totally bulge free disc galaxies which still have actively growing supermassive black holes in their centres.

http://blog.galaxyzoo.org/2012/07/04/galaxy-zoo-at-the-european-week-of-astronomy-and-space-science/

[zutopian]

"Galaxy Zoo: Bulgeless Galaxies With Growing Black Holes"
B. D. Simmons, C. Lintott, K. Schawinski, E. C. Moran, A. Han, S. Kaviraj, K. L. Masters, C. M. Urry, K. W. Willett, S. P. Bamford, R. C. Nichol
(Submitted on 17 Jul 2012)
http://arxiv.org/abs/1207.4190

[echo-lily-mai]

"Galaxy Zoo: Bulgeless Galaxies With Growing Black Holes"
B. D. Simmons, C. Lintott, K. Schawinski, E. C. Moran, A. Han, S. Kaviraj, K. L. Masters, C. M. Urry, K. W. Willett, S. P. Bamford, R. C. Nichol
(Submitted on 17 Jul 2012)
http://arxiv.org/abs/1207.4190

Great! Thanks for all the posts zutopian 

[zutopian]

Great! Thanks for all the posts zutopian 

You are welcome. Thanks for starting this topic!

[zutopian]

"Galaxy Zoo: Bulgeless Galaxies With Growing Black Holes"
B. D. Simmons, C. Lintott, K. Schawinski, E. C. Moran, A. Han, S. Kaviraj, K. L. Masters, C. M. Urry, K. W. Willett, S. P. Bamford, R. C. Nichol
(Submitted on 17 Jul 2012)
http://arxiv.org/abs/1207.4190

I looked at the images of the galaxies, which are presented in that paper.
First I was confused, because they look different than NGC 4395, but I guess, that it is due to pseudo-bulges.:

Ten compact host components have n < 2 and are thus considered pseudobulges.

Table1

[zutopian]

However, owing in part to the compounded rarity of both massive, bulgeless galaxies and active galactic nuclei (AGN),
the the extent to which a SMBH can grow in the absence of merger processes remains difficult to characterise.

Oops, the word "the" is twice in above sentence, which is on page 2 of that GZ paper!