Peas Project

[fluffyporcupine]

Hiya Fluffy? I hope all is well with your engineering. Remember this thread? It was you
who first explained where doubly-ionised oxygen was in the spectrum. Cool.

Posted by Nightwatch,   Dec. 10.
What Is This Green Colored Thingy?
http://www.galaxyzooforum.org/index.php?topic=8926

it just doesnt look like a typical pea to me (visually rather than spectrum wise) and engineering is goign well thanks

[ElisabethB]

it has the right color, but sadly no spectrum 
587742061603258482

[fluffyporcupine]

posted by Q here
587739706335297717

[j_doe]

I actually found one!  (It looks as if it has been cooked almost long enough.)

http://cas.sdss.org/astro/en/tools/explore/obj.asp?id=587742013266985266



Spectrum

[laihro]

Hi Carie,

sorry but I'm one of the more impatient people. I have created a database for you. It contains a basic set of 800 candidates. I also included a couple of queries that give different views for the peas with no respect to their color. Additionally, there is a query "greenishStuffOnly" that selects 186 objects according to your initial specification.

database: here
                 |
                 v

[laihro]

To find duplicate easier here the list of 186 greenish OIII objects. I will look for earlier posts and give references as soon as possible.
The selection limit I chose is quite arbitrary. So, I think there are still some objects left to be found.

Edit:I reviewed this list and removed 76 objects that are already on Rick's list. I also removed some objects that are not as green as they should be.

Photo Object - Spec Object
587738947196944678 541786908364111872
588010360696209599 236663927444865024
587738570859413642 500130878568005632
                       none 115064361977905152
587726878884692397 203449235012583424
587739376706978028 550794566979026944
587745243085013206 685341275162935296
587745243087372534 687030089728131072
588017114517536797 392884475173797888
587741816245387433 665356280742805504
587742863132983414 700259559851163648
587739096987271268 573031085898727424
587739610239402144 555016842003873792
587741534393598186 664230653180510208
587739720849555951 621728162019016704
587741392649781464 661134131559661568
588017605211390138 382189325120438272
588848899909943451 79597814920773632
587733441055359356 377684658189500416
588013384336998734 243419094156574720
587733609091236150 330396879844016128
588018056199012708 474232522759208960
587729229297090692 173331941871845376
587738371672178952 542349800209645568
587726032253419628 146873201631166464
587730774965354630 212174998977118208
587726102030451047 167419670226272256
587739706874724542 602306381382418432
587741601501085839 631579416505352192
588023048021868671 660571083518246912
587733411516842159 293523379556712448
588018090013098618 398233830344884224
587741490903974025 661697116661350400
587725550133444775 217523632648224768
588009371762098262 218367714442346496
587725041706074227 94235953001922560
587741708865700132 642275109616222208
587732151496147105 342781272638095360
587735664780640637 376277168012918784
587741709403750673 642838138749714432
587727178986815586 183464155003486208
588017978351616137 562053559906992128
588848898845638824 82695480772919296
587732590643445978 269315138933227520
587724649803022514 96204976413474816
587739304219312312 569373588625293312
588011122502336742 219212317798170624
588023240745943289 664511706654834688
587742010046808228 683370902372483072
587732582055870602 267626191991603200
587726032799400204 149967997929259008
587725576962244831 99864587058282496
587734621628989647 356856138198679552
587733080807506110 284515854677180416
587731185663344827 108027473324670976
587728919520608387 170517217916485632
587733398646620415 297744632819744768

[Rick Nowell]

So, I think there are still some objects left to be found.

Yes, I would guess there are...

In order to be USEFUL, this list needs to be NUMERICALLY sorted, so it is very much easier
to see what is what. At the mo', it is fairly useless- you want us to go through the whole
list? The way I initially sorted the first list was by making each object file into a folder,
which can then be sorted using Windows as per usual. As a programmer, you might be
able to shorten the process.

Secondly, what is in your list that has already been posted?

Thirdly, very well done indeed, but you need to sort it much more for it to be useful as a
database. It is too higgeldy-piggeldy to be of any benefit.

Fourthly, cool. Have you been through each one individually? 

[laihro]

Hi Rick,

In order to be USEFUL, this list needs to be NUMERICALLY sorted, so it is very much easier
to see what is what. At the mo', it is fairly useless- you want us to go through the whole
list?

This list is sorted by my pea rating height / average descending. To check whether an object you are about to propose here is already one of the 186 I would suggest to hit [ctrl]+[f] (in firefox) and search for the photo object id. Or simply use the search function of the forum.

The way I initially sorted the first list was by making each object file into a folder,
which can then be sorted using Windows as per usual. As a programmer, you might be
able to shorten the process.

I gave you an Excel file containing the top 750 classic peas, because Excel provides means to order a table by any of its columns, without requiring any SQL knowledge

Secondly, what is in your list that has already been posted?

[..] I will look for earlier posts and give references as soon as possible. [..]

Thirdly, very well done indeed, but you need to sort it much more for it to be useful as a
database. It is too higgeldy-piggeldy to be of any benefit.

This is the database. You can sort it in any way you like. As I mentioned it also contains some example queries that demonstrate how to sort.

Fourthly, cool. Have you been through each one individually? 

No, I took samples and trust in my selection criterion for the remaining.

[Rick Nowell]

We, you, have to make this as easy as possible for Carie to use. Is that how it is at the moment?

We, you, have also to take a deep breath and condense the numbers we are generating into
'the list'. It would be useful to know how many is needed for the paper- perhaps Zookeeper
Kevin can tell us. Some are very maybe, whereas others are pure peas. We need to get a list
that is as 'pure' we can make it- little is open to interpretation.

THANKYOU for your hard work. I feel that to use your programming skills effectively, we must be
very rigorous and drop the maybes- they will take away from the really amazing deep green
peas that we come across.

My list is much the same. It has 106 peas, but how many could we put as objects for a paper?
Some advice is needed, for me, about the numbers and the 'pureness' of the galaxies we have.
These objects are rare...

These shouldn't be here (from your list) IMHO:

http://cas.sdss.org/astro/en/tools/explore/obj.asp?id=588017110224273454
 
etc. etc. for a lot of them...

[zookeeperKevin]

We, you, have to make this as easy as possible for Carie to use. Is that how it is at the moment?

We, you, have also to take a deep breath and condense the numbers we are generating into
'the list'. It would be useful to know how many is needed for the paper- perhaps Zookeeper
Kevin can tell us. Some are very maybe, whereas others are pure peas. We need to get a list
that is as 'pure' we can make it- little is open to interpretation.

Hi Rick,

To answer your question, we need to distill a list of "pure" peas only. How many do we need? Ideally, we'd like to get all peas that fit the classic/pure description so that we can not only study them, but also figure out how common (or rather, rare) they are. If we know that we have all "peas" in a certain area of the sky (e.g. all of SDSS), we can then work on things like their number density (number per unit volume) and their clustering.

If you guys just post the object ID, Carie and I have computer programs to gather everything else about them automatically, so just the objid is fine.

Cheers,
Kevin

[mrgoodwraith]

You could call yourselves the "Peas Brigade".

What, not the "Peas Corps"? 

[ccardamone]

Hi,
   Thanks so much for all the help!  As Kevin said the object ID is enough for us to add them to our list.  If you could sort through them so that you know each object ID you're posting has a spectrum (because if it doesn't, even if the object is small and green it could be so many other types of objects, eg. the redshift 6 quasar).  Also make sure the redshift is 0.15<z<0.45 and you can see the OIII line.
   Running queries is great, but could you let everyone on the forum know if you've looked through them by eye.  We want to make sure our Peas list is appropriately vetted.  And that all of the objects are small and green.  If it looks like its bigger then the images of stars or has any shape, its probably not what we're looking for.

thanks!
Carie

[ccardamone]

May I ask, why you are putting an upper limit on the redshift? I mean, it's not like any important emission line becomes invisible in the spectrum at z>0.45. [OI] fades out at this point while [H-alpha] is long gone then. There is no green OIII object from z>0.38 anyway. OIII dominated objects appear red in the range 0.38<z<0.65, see the color survey and the color discussion. Never mind, I'm sure there is a good reason for that upper redshift limit. I just would like to hear it. 

Hi,  The only reason we've applied that redshift range is to narrow our scientific question.  We'll start by looking for the Peas - which we've defined as green.  Its also important to note as you look further out in redshift, the same galaxy would be much fainter.  So a galaxy seen at z=0.1, might be missed in a sample looking at z=0.5.  So we'd like to try and look at one small sample of galaxies to start our investigation.

[ccardamone]

Some have colours that are open to interpretation! Mainly blue/greens, that sort of thing.

http://cas.sdss.org/astro/en/tools/explore/obj.asp?id=587725818034913419   

Hi Rick,   These are interesting.  They are small, compact and greenish.  But have a bit more of a blue tint to them.  I think the blue color is coming from the addition of an OII line in the spectrum.  Lets leave them in the sample for now and we can try and Kevin and I will investigate their spectrum to see how different they are.
That said, I think my main interest right now is on the ones that look very 'green'. 

thanks!

[ccardamone]

I had some great questions by message I thought I should answer here for all:
>We have been trying to collect these Peas for six months now, and it
>became somewhat obsessive! The green ones are pretty rare
>From what I understand, as a layperson, the galaxies (compact dwarfs?) are green
>because of how the colour has been redshifted from the original intense blue, but
>also from the amount of [OIII] present when compared to the other ingredients.

>Why the green ones are preferable to study rather than others is something that
>could be explained a bit more in the thread? I am not a scientist and often wonder
>why these galaxies are green in SDSS, but not in other sources.

Most galaxies (almost all the ones we see in SDSS & galaxy zoo) fall into 2 classes - the ellipticals, these tend to be red or the spirals, which tend to be blue.  Both classes of galaxies are much larger then the Peas.  The emission lines we see in the peas (that big OIII line) is cause by hot gas.  The heating source for gas in galaxies is sometimes a black hole (this is the quasars and AGN that are being collected in some of the other threads) or young hot stars.  By studying the Peas emission lines in greater detail we can determine the temperature of the the heating source of the gas and reveal whether its a black hole (it would have to be surrounded by lots of gas to look anything like the peas' spectrum) or if its star formation.

I think part of the reason we're so interested in the Peas is that they don't fall so neatly into any of the typically studied categories. They appear to be quite small and compact, but certainly aren't stars or distant quasars.  At first glance, they have emission lines like star forming galaxies & buried AGN, but they are much smaller then what we'd expect to see at these nearby redshifts.  (Or at least these redshifts seem nearby to me because I spend the rest of my time studying the Deep Fields.)

Please feel free to ask me any other questions.  I know that there are people with a variety of different Astronomy backgrounds reading this.  Also, if you're an expert with other ideas of why the Peas are so interesting - post away    I study star formation in AGN host galaxies, so of course those two lines of study are the first things I think of when confronted with the Peas.