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GALEX Observations - COSMOS


Galaxy Evolution Explorer
An Ultraviolet Imaging and
Spectroscopic Survey

Morphologies of Star-
Forming Galaxies out to

May 21, 2005
David Schiminovich
Michel Zamojski
Columbia University
M. Rich UCLA +
GALEX and COSMOS teams
                       GALEX vs. COSMOS
                         NUV       I814W
                     FUVFUV NUVI814W
                                            GALEX Bands
                                    z=0.7   FUV (1530 A)
                                            NUV (2310 A)

                                            GALEX FOV:
                                            1.2 deg. diam

                                            PSF: 5” (FWHM)

 SSP - Bruzual and
   Charlot (2003)                                 May 23, 2005
               GALEX/COSMOS Field
Deep Imaging Survey   01                   03
Obs. Spring 2004

4 targets in region
on 0.5 degree grid

50 ks each
100, 150, 200 ks in
overlap regions
mAB <25-26

                      02                     04
COSMOS KYOTO                 1.4O   May 23, 2005
   Observing Status - Spring 05 (IR1.1)

Central pointing (COSMOS_00)

   • Shallow imaging (~3 ks processed)
   • Shallow grism spectroscopy (~20 ks)
   • candidate for deeper follow-up

No additional COSMOS observations in Spring 05

   • Schedule availability limited
   • Spectroscopy observations given lower priority
   • GALEX FUV detector off

COSMOS KYOTO                                          May 23, 2005
    Processing Status - April 05 (IR1.1)
Integration time on four fields (target was 50ks):

       COSMOS_01 - 44024 s
       COSMOS_02 - 44442 s
       COSMOS_03 - 41270 s
       COSMOS_04 - 44169 s
       (85-90% observed data passed checks)

Catalog Refinements

   • Source confusion/deblending
   • Background Subtraction - faint source photometry
   • Significant progress has been made in these areas

COSMOS KYOTO                                         May 23, 2005

COSMOS KYOTO         May 23, 2005
               GALEX/COSMOS Field
                          Green Contours: GALEX NUV
                          Image: COSMOS ACS

COSMOS KYOTO                              May 23, 2005
           GALEX Data Release Plan

GALEX/COSMOS images and catalogs will be released to
public as part of GALEX GR2 (second data release) in late
Fall 2005

       Pipeline outputs only

Will also be provided to IRSA at that time

GALEX has suffered serious funding cut, and FUV
problems which affects our ability to process the COSMOS

COSMOS KYOTO                                      May 23, 2005
           GALEX/COSMOS Catalog

New GALEX/COSMOS matched catalog using latest
COSMOS photo-z cat (05/2005)

   • Photometry using optical prior (positions only)

   • Michel Zamojski (grad student at Columbia)
   performing reduction/analysis

   • Can provide catalogs and images for COSMOS
   projects (or participation in analysis effort) upon

COSMOS KYOTO                                           May 23, 2005
                                           Schiminovich et al (2005)

               - Seibert et al 2005

COSMOS KYOTO                                            May 23, 2005
           GALEX/COSMOS Science

Nearly 100,000 galaxies have been detected by GALEX
down to NUV~25.5 over the full field.

COSMOS has no better tracer of SFR in the range 0<z<1
than the GALEX FUV and NUV observations (even w/
caveats of dust attenuation and SFH)

COSMOS KYOTO                                   May 23, 2005
 Short-term GALEX/COSMOS Projects
Morphological Properties of Star-Forming Galaxies at
  0.5<z<1.0 using COSMOS/GALEX(Zamojski, DS, Rich et al)
   •   Apj Letter part of Zamojski PhD thesis (also see next few slides)
   •   Overall project combines other local and deep data sets. For
       this reason Michel has measured his own morphologies
   •   Willing to distribute morph. catalog to team and/or use other
       morph. catalogs for some analysis
   •   Comparison morphologies in ugriz have been measured using
       SDSS NYU low-z galaxy catalog (can also provide to team)

GALEX Far and Near Ultraviolet Observations of the
  HST/COSMOS Survey Region (DS, Zamojski, Rich et al)
   •   Basic description of GALEX observations, properties and initial
   Letter + Paper will be distributed to team/ready for submission in
COSMOS KYOTO                                                 May 23, 2005
       GALEX/COSMOS Projects (~1 yr)
• Morphological evolution of star-forming galaxies and the evolution of
rest-frame ultraviolet luminosity function/density vs. morphological type.
(Zamojski, DS, Rich, et al)

• Physical properties of star-forming galaxies at 0.5<z<1.0 (Rich, Salim,
DS, et al)

• SFR/Mass vs. morphology (DS, Rich et al)

• Morphological properties of galaxies at SF extremes (starburst/LBGs,
~k+a/red objects) (Rich, DS et al)

• Evolution of UV extinction properties and dependence on morphological
type, size. (would be excellent to combine w/ VLA/COSMOS, possibly X-
ray and some Spitzer data)

• Evolution of UV luminosity/SFR vs. density/local environment
 COSMOS KYOTO                                                    May 23, 2005
             GALEX/COSMOS Analysis
Over full 2 sq. deg:
>75k GALEX matches
w/ optical data NUV<25

Analysis for 1 sq. deg:
(using Dec/Jan photo-z and
Cycle 12 ACS data)

High S/N I-limited sample with
I<23 and good photo-zs
(17k objects)

NUV<25 (9k galaxies)

Redshift Range: 0.55<z<0.8

Quantities measured:
ACS: Morphology, r50
 COSMOS KYOTO                        May 23, 2005
    I.     Morphology of FUV luminous vs.
           FUV faint galaxies at 0.55<z<0.8
Non-parametric morphologies:

         Concentration          (C)        B/D, Type
         Asymmetry              (A)        Merger
         Clumpiness             (S)        Star Formation
         Gini Coefficient       (G)        B/D, Type
         M20                    (M20) B/D, Merger
following work of Abraham et al (1996), Conselice (2003), Lotz et al

•17000 total CASGM measurements from ACS/COSMOS
•5540 in redshift slice 0.55<z<0.8
COSMOS KYOTO                                                 May 23, 2005
I. Morphology of
  FUV luminous
 vs. FUV under
   galaxies at

 MFUV < -18

 MFUV > -18

 2.5k galaxies
 each bin
  II. Sizes of extreme UV-luminous galaxies
          Local Measurement: Heckman, Hoopes et al (2005)
LFUV,bol > 2x1010 Msol
SFR 5-50 Msol/yr                           Large

SDSS u-band half-light
radius (circles)

Compact galaxies may
be LBG analogs
with high SFR/area and

Large galaxies may be
extreme disks

COSMOS rest frame
V-band half-light radius (squares)
 COSMOS KYOTO                                                May 23, 2005
  Compact UV Luminous Galaxies (UVLGs)
      r50~2.5 kpc     0.55<z<0.8

COSMOS KYOTO                     May 23, 2005
    Large UV Luminous Galaxies (UVLGs)
        r50~10 kpc     0.55<z<0.8

COSMOS KYOTO                       May 23, 2005
     Conclusions and Work in Progress
• GALEX has performed deep imaging entire 2 sq. deg.
  COSMOS field
• At 0.55<z<0.8, FUV luminous galaxies have higher
  Concentration, Clumpiness, Gini Coefficient, M20 (and
  somewhat higher Asymmetry) than their FUV faint
• At 0.55<z<0.8, UVLGs (extreme UV luminous galaxies)
  have half-light radii roughly consistent with range seen in
  local sample, where both compact and large galaxies are
  seen. Locus slightly higher than for typical LBG.

Work in Progress
• Further investigation into relation between morphology,
  SFR and mass and evolution w/ z.
• Morphologies of local comparison sample
              Of General Interest …

• GALEX photometry could be used to constrain better the
  photo z’s especially for star forming galaxies z<1.5

• Would be useful to have final throughput bandpasses as
  a function of  for all optical/IR flux points >> Salim’s
  physical parameters (masses, SFR, etc.). Can this be
  made available on web site?

• We could add these derived parameters to the data set.

• Should a U-cosmos proposal to “finish” Galex
  photometry of the field and to add ~200 ksec of
  spectroscopy be proposed?

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