J. E. Hibbard (NRAO), with:

1
Spitzer Observations of Hickson Compact Groups of
Galaxies

• J. E. Hibbard (NRAO), with
• K. Johnson (P.I., UVa), A. Heiderman (NRAO REU),
  S. Gallagher (UCLA), A. Hornschemeier (GSFC) J.
  Charlton (PSU)

2
Compact Groups

• Hickson 1982
• Richness Ngt3 with mltm13mag
• Isolation Rneighborgt3Rgroup
• Compactness ?Glt26 mag/arcsec2
• (selected off of red plates, so bias towards
  early types)
• May be stage in evolution to cluster core, field
  early type, fossil group, or dry merger
  remnants (c.f. yesterdays talk by Emanuela
  Pompei)
• Stay tuned to meeting - 6 more CG talks on
  schedule!

3
Spitzer Survey of HCGs

• Kelsey Johnson (UVa) P.I.
• IRAC and MIPS imaging of 12 close HCGs spanning a
  range of evolutionary states
• Use MIR to conduct a complete census of activity
  (AGN star formation) and dust content of HCGs
• This is VERY MUCH a work in progress! (some
  photometry completed yesterday). See Kelseys
  presentation Amandas poster at January AAS
  (Washington D.C) for actual results!

4
Spitzer IRAC 3.6, 4.5, 5.8, 8 ?m bands MIPS
24?m

Starburst SED Models
Dust Stars
Spitzer
Radio ---gt
3.6?m 8?m 24?m
Brent Groves, 2005
5
Spitzer IRAC MIPS Mid-IR Imaging
3.6 ?m
4.5 ?m
Mostly Stars, some PAHs
Just Stars
5.8 ?m
8 ?m
24 ?m
Some Stars, mostly PAHs
PAHs
Hot dust
6
So whats a nice radio astronomer like me involved
for?

• Compact groups are deficient in HI with respect
  to field galaxies of the same type

Nearby galaxies
Virgo
Compact groups
Virgo core
Huchtmeier 1997
7
Verdes-Montenegro et al. 2001
Compact groups
Virgo
Coma I group
Coma
8
HI properties of 324 isolated galaxies Haynes
Giovanelli, 1984
9

• Evaluate evolution of HCGs, especially with
  respect to their cold gas content and proposed
  evolutionary scenario

(L. Verdes-Montenegro, 2001)
10
Can this help us understand quenching of star
formation in massive galaxies??
11
In models, continued infall slows color evolution
of remnants
(Somerville 2005)
12
SAMs can reproduce observed bimodality by
truncating SF when bulge gets above some critical
value
Mcrit2x1010 Mo
(Somerville 2005)
13
Spitzer IRAC 3.6?m, 4.5?m, 5.0?m, 8.0?m color
images
14

• Phase 1 HI in individual galaxies.
• HCG 02
• HCG 61
• HCG 59
• HCG 19
• HCG 22
• HCG 07
• at least one member HIdef
• all members HIdef

(L. Verdes-Montenegro, 2001)
15
HCG 02 (N3)
Not HI Def
OpticalHI
R-band
Halpha
X
Vilchez Iglesias-Paramo 1998
Verdes-Montenegro 2001
24um
IRAC
Log Lxlt41.1
16
HCG 61 (N3)
Not HI Def
R-band
Halpha
X
Vilchez Iglesias-Paramo 1998
24um
IRAC
Log Lxlt41.6
17
HCG 59 (N4)
Not HI Def
X
IRAC
Optical
E
A
D
B
C
Log Lxlt41.7
18
HCG 19 (N32)
Not HI Def
OpticalHI
Optical
A
C
B

X
D
VLA Archive
No X-ray
IRAC
24um
19
HCG 22 (N3)
DefHI0.59
OpticalHI
Optical
A
C

B
X
X
E
ATCA Archive, thanks to B. Koribalski
D
ROSAT
AdSy2
(Log Lx40.6)
IRAC
24um
Mulchaey et al. 2003
20
HCG 07 (N4)
DefHI0.64
R-band
Halpha
IRACHI




Vilchez Iglesias-Paramo 1998
VLA Archive
24um
IRAC
Log Lxlt41.7
21

• Phase 2 HI being tidal removed from galaxies.
• HCG 31
• HCG 16
• at least one member HIdef
• all members HIdef

(L. Verdes-Montenegro, 2001)
22
HCG 16 (N42)
DefHI0.41
OpticalHI
R-band
Halpha



Vilchez Iglesias-Paramo 1998
Verdes-Montenegro 2001
24um
XMM
IRAC
BSy2
ALNR
CSBNG
DLNR
Log Lx41.0
23
HCG 31 (N42)
OpticalHI
R-band
Halpha

Vilchez Iglesias-Paramo 1998
Verdes-Montenegro 2001
DefHI0.57
24um
IRAC
Log Lxlt41.2
24

• Phase 4 X-ray medium. no HI in central galaxies
  deficient galaxies in the outskirts
• HCG 48?
• HCG 90
• HCG 62?
• ?no HI map
• all members HIdef

(L. Verdes-Montenegro, 2001)
25
HCG 90 (N41)
DefHI1.4
ASy2
IRAC
A
OpticalHI

B
C

D
ROSAT
Log Lx40.8
DLNR
Mulchaey et al. 2003
26
HCG 48 (N4)
DefHI0.82
IRAC
D
C
ROSAT
A
B
24um
Log Lx41.6
Mulchaey et al. 2003
27
HCG 42 (N4)
E dominated
IRAC
C
ROSAT
A
B
D
24um
AdLNR
Log Lx41.8
Mulchaey et al. 2003
28
HCG 62 (N4)
E dominated
Chandra
IRAC
B
C
A
D
Log Lx42.9
29
So what can we do with the MIR data?

• SEDs give dominant activity
• Spatially separate SED

30
Def vs. MIR SEDs
Stars
HCG7C Def0.55
PAHs
HCG7D Def0.55
HCG7B Defgt1.3
HCG7A Def0.85
PAHs warm dust
31
Trends with MIR Colors
Bluenot HI Def RedHI Def
AGN
3.6-4.5 (mag)
PAHs
stars
4.5-8.0 (mag)
32
Trends with MIR-FIR Colors
Bluenot HI Def RedHI Def
hot dust
stars cool dust
cool dust
8-24 (mag)
no dust
stars
4.5-8.0 (mag)
33
MIR and FIR Colors vs. DEF
3.6-4.5 (mag)
4.5-8.0 (mag)
8-24 (mag)
8-24 (mag)
4.5-8.0 (mag)
3.6-4.5 (mag)
34
SFR24um vs. Def
35
Nuclear vs. Extranuclear MIR SEDs

• HCG 90

PAHs Hot dust
Mostly starlight
HCG 90D DefHIgt2.0
36
Conclusions

• None yet. But track down Kelsey or Amanda
  Heiderman at January AAS Meeting

37
(No Transcript)
38
HCG 02
IRAC
OpticalHI
39
HCG 07
IRAC
OpticalHI
40
HCG 16
IRAC
OpticalHI
41
HCG 19
IRAC
OpticalHI
42
HCG 22
IRAC
OpticalHI
43
HCG 31
IRAC
OpticalHI
44
HCG 42
IRAC
OpticalHI
Map Not Available
45
HCG 48
IRAC
OpticalHI
Map Not Available
46
HCG 59
IRAC
OpticalHI
Map Not Available
47
HCG 61
IRAC
OpticalHI
Map Not Available
48
HCG 62
IRAC
OpticalHI
Map Not Available
49
HCG 90
IRAC
OpticalHI
50
Project Goals

• Optical images of the 12 Hickson Compact Groups
  (Hickson 1982) in the sample they were chosen
  for this study based on distance (closest),
  angular extent (lt 8 arcmin diameter), and
  membership (at least 3 galaxies with redshifts
  within 1000 km s-1 of the mean).
• Dotted blue lines enclose the groups with
  complete Spitzer data to date the remainder will
  have a full suite of IRAC and MIPS (24 and 70 mm)
  imaging by the end of Cycle 1.