2005-09-14nvo summer school, aspen, colorado1 finding and exploring merging pairs of galaxies in...
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2005-09-14NVO Summer School, Aspen, Colorado 1
Finding and Exploring Merging Pairs of Galaxies in 2MASS using the NVO
Sahar Allam, Perry Gee, Yeong Loh,
Ivanio Puerari, Douglas Tucker
2005-09-14NVO Summer School, Aspen, Colorado 1
Goals
• Use the NVO to identify (relatively) isolated merging pairs of galaxies from the 2MASS eXtended Source Catalog (XSC)
• Perform exploratory research into the properties of the pairs and their member galaxies (NIR, Optical, Radio, X-Ray)– Existence of hot or cold gas surrounding
individual pairs– Star Formation/AGN Properties (e.g., like in
Chris's and Simon's talks)
2005-09-14NVO Summer School, Aspen, Colorado 1
Finding Merging Pairs in 2MASS
• Used Open Sky Query to download 125 sq deg of data (ra, dec, J, H, Ks, rext, flags) from the photoXSC table in the TWOMASS database
D>20xss<4di
i
j
• Modified Karachentsev Criteria
2005-09-14NVO Summer School, Aspen, Colorado 1
The Catalog (SDSS astrotools)
• 91 candidate merging pairs in 125 sq deg– some are garbage (~10%)
DEC
RA
+1.25° -
-1.25° -
0° 50°
2005-09-14NVO Summer School, Aspen, Colorado 1
Image Gallery (Optical/SDSS SkyServer)
2005-09-14NVO Summer School, Aspen, Colorado 1
Image Gallery (Opt.,NIR, Radio/SkyView)
2005-09-14NVO Summer School, Aspen, Colorado 1
Image Gallery (NIR & Radio/SkyView)
• image: 2MASS Ks; red contours: FIRST
2005-09-14NVO Summer School, Aspen, Colorado 1
Photometric Properties (NIR/TOPCAT)
• concordance in Ks magnitude?
Ks
(gala
xy
1)
Ks (galaxy 2)
11.5
14.5
11.6
14.6
2005-09-14NVO Summer School, Aspen, Colorado 1
Photometric Properties (TOPCAT)
SDSS g-r vs u-g
2MASS H-Ks vs J-H
2MASS J-H vs SDSS i-z
GALEX nuv – fuv
u-g i-z
fuv magJ-H
g-r
H-K
s
J-H
2005-09-14NVO Summer School, Aspen, Colorado 1
Redshifts (matches with SDSS)
redshift
0.00
0.10
0.20
0.30
Nu
mb
er
0
18
2005-09-14NVO Summer School, Aspen, Colorado 1
Spectra (SDSS)
Pair 8
8-951
8-952
z=0.0631
z=0.0636
dv ~ 150 km/s
2005-09-14NVO Summer School, Aspen, Colorado 1
Spectral Classfication (Open Sky Query)
SELECT t.ra, t.dec,t.pairid,t.objid,t.matchobjid, s.specobjid, s.z,s.zerr,s.zWarning, s.velDisp, s.velDispErr, s.specClass, s.eClass, s.plate,s.fiberID,
l.height, l.sigma, l.wave,l.restWave,l.z
FROM SDSSDR3:PhotoPrimary o, SDSSDR3:SpecObj s,SDSSDR3:SpecLine l,Mydata:MergePair t
WHERE o.specobjid = s.specobjid and l.specobjid = s.specobjid and XMATCH(o, t) < 3.5 and s.zWarning=0 and l.restWave between 5008.2 and 5008.3
ORDER BY t.pairid
2005-09-14NVO Summer School, Aspen, Colorado 1
Spectral Classification ( TOPCAT/IDL)
log [N II] / [Halpha]
log [
O II]
/
[Hb
eta
]
AGN
Starbursts
2005-09-14NVO Summer School, Aspen, Colorado 1
Future
• AstroGRID or other GRID resources to do full 2MASS XSC (all-sky)
• Move from web-based to command-line-based queries
• NVO Research Initiative proposal? (Oct 1!)
2005-09-14NVO Summer School, Aspen, Colorado 1
Extra Slides
2005-09-14NVO Summer School, Aspen, Colorado 1
Tools
• Open Sky Query– download 2MASS XSC data– match 2MASS merging pair galaxies with
SDSS, FIRST, XMM, ROSAT, and GALEX catalogs
• Topcat and VOPlot– analyze photo. and spectro. properties of pairs
• SkyView– obtain 2MASS, FIRST, and X-ray images of pairs
• SDSS SkyServer– obtain optical images of pairs
2005-09-14NVO Summer School, Aspen, Colorado 1
2MASS Merging Pairs at z>0.2