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TRANSCRIPT
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Wallaby science meeting - Dec 2 2010
Westerbork ultra-deep HI observations at z=0.2
Glenn Morrisson (Hawaii)Bianca Poggianti (Padova)David Schiminovich (Columbia)Arpad Szomoru (JIVE)Marc Verheijen (Kapteyn)Min Yun (UMASS)
Aeree Chung (CfA)Ryan Cybulski (UMASS)Boris Deshev (Kapteyn)K.S. Dwarakanath (RRI)Jacqueline van Gorkom (Columbia)Maria Montero-Castano (Columbia)
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Wallaby science meeting - Dec 2 2010
HI, ICM, SFR, SFH, SPs and the environment
Bravo
-Alfaro
et al, 2001
Poggian
ti & van
Gorko
m, 2
001
Coma Abell 2670
What is the role and fate of cold gas in galaxy evolution?
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Wallaby science meeting - Dec 2 2010
Why clusters at higher redshift?
! Exploratory steps towards understanding the role and fate of cold gas in cosmological evolution.
Why Z~0.2 ?! Highest redshift for ‘practical’ HI imaging with existing arrays
! Lowest redshift where cosmological evolutionary effects are seen
Content of galaxy clusters and the surrounding field evolves over cosmic time.
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0 0.1 0.2 0.3 0.4 0.5
redshift
0
0.1
0.2
0.3
0.4
blu
e fr
action
Abrah
am et al, 1
996
Butcher-Oemler effect
The fraction of blue (starforming?) galaxies in clusters increases with redshift and peaks in cluster outskirts.
A963
Key question: different accretion rate/efficiency or different field population?
Butch
er & O
emler, 1
984
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Morphological mix in clusters depends on redshift and compactness
Fasano et al, 2
000
• HEC LEC
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Clusters of different compactness
Concentration of ellipticals:
High " S0/E low Low " S0/E high
Fasano et al, 2000
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Wallaby science meeting - Dec 2 2010
Goals of HI observations at intermediate z
• Characterize nature of blue galaxy population " gas content, SFR, stellar populations
• Witness galaxy transformation in various environments " which physical mechanisms dominate where? gas accretion and depletion
• SFR versus environment and gas content
• Evolving !HI from blind HI 21cm emission surveys
• Evolving HI Mass Function? " HIMF in different environments
• HI based Tully-Fisher and rotation curve studies
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Wallaby science meeting - Dec 2 2010
1 Mpc 1 Mpc
z=0.188z=0.206INT - B,R
A tale of two clusters
Abell 2192Abell 963
work in progress( thesis Boris Deshev )
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Wallaby science meeting - Dec 2 2010
1 Mpc 1 Mpc1 Mpc1 Mpc
z=0.188z=0.206INT - B,R
A tale of two clusters
Abell 2192Abell 963
work in progress( thesis Boris Deshev )
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Wallaby science meeting - Dec 2 2010
INT - 2.5m SDSS
SDSS @ Z=0.2 is of insufficient qualityto determine morphologies and detect LSB galaxies.
B: 5x15minR: 5x 6min
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Wallaby science meeting - Dec 2 2010
Ultra-deep WSRT observations
• Minimum detectable HI mass: 2x109 Msun over 150 km/s profile width
(4" in each of 3 spectral resolution elements)
• Corresponding limiting column density:
3x1019 (cm-2) over 80 km/s profile width at 7".
This requires: 78x12hr for A2192 at z=0.188
117x12hr for A963 at z=0.206
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Wallaby science meeting - Dec 2 2010
Survey Volume & Large Scale Structure
SDSS redshift slice
325 Mpc
combined volume: 7x10 Mpc4 3
HIPASS
Alfalfa
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Wallaby science meeting - Dec 2 2010
WSRT observational setup
• Long-term program over 8 semesters
• 8x10MHz bands, overlapping to cover 1160-1220 MHz Z = 0.164-0.224 , surveyed volume # 70,000 Mpc3
• 8x256 channels, covering 18,000 km/s velocity range 20 km/s velocity resolution (after Hanning smoothing)
• dual polarisation, 2-bit correlation, recirculation
• 117x12hr on Abell 963 , 78x12hr on Abell 2192
rms noise per channel: 14 $Jy and 17 $Jy (%V=80 km/s)
~5-15% lost to RFI, antenna 5 offline (APERTIF prototype)
Verheijen et al, 2007, A
pJ Lett, 6
68, 9
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Wallaby science meeting - Dec 2 2010
WSRT observational setup
• Long-term program over 8 semesters
• 8x10MHz bands, overlapping to cover 1160-1220 MHz Z = 0.164-0.224 , surveyed volume # 70,000 Mpc3
• 8x256 channels, covering 18,000 km/s velocity range 20 km/s velocity resolution (after Hanning smoothing)
• dual polarisation, 2-bit correlation, recirculation
• 117x12hr on Abell 963 , 78x12hr on Abell 2192
rms noise per channel: 14 $Jy and 17 $Jy (%V=80 km/s)
~5-15% lost to RFI, antenna 5 offline (APERTIF prototype)
Verheijen et al, 2007, A
pJ Lett, 6
68, 9
A963 A2192
semester # measurements
2005 -A 20-B 15
2006 -A 33 15-B 5
2007 -A 33 12-B 3
2008 -A 31 8-B 15
total 117 73
hours 1404 876
pilot study
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achieved rms noise
A2192
A963
Flagged: 5-8% 15-17%
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Wallaby science meeting - Dec 2 2010
achieved rms noise
A2192
A963
Flagged: 5-8% 15-17%
before after
0 256 0 256channel
tim
e
0 hr
12 hr
channel
10 MHz 10 MHz
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IF-based selfcal
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Wallaby science meeting - Dec 2 2010
Abell 2192 Abell 963
" = 7 $Jy/beam (confusion limited) " = !12 $Jy/beam (DR limited)
continuum
SFR # 10 Msun/yr ( deep GALEX data more sensitive )
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Wallaby science meeting - Dec 2 2010
%V = (1+Z)!C!%f/f0 = (1+Z)!8.24 km/s
Velocity smoothing the data cubes:
R2 : R = 2%V = 20 km/s # 1544 channelsR4 : R = 4%V = 40 km/s # 768 channelsR6 : R = 6%V = 60 km/s # 510 channelsR8 : R = 8%V = 80 km/s # 383 channels
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Wallaby science meeting - Dec 2 2010
Abell 2192 Abell 963
R=80 km/s" = 17 $Jy/beam " = 14 $Jy/beam
Detection criteria: 1x8" or 1.5x6" or 2x5" or 3x4" or 4x3" in N consecutive spectral resolution elements.
line cubes
Spectrally smoothed to R=20, 40, 60, 80 km/s
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Wallaby science meeting - Dec 2 2010
R2 R4 R6 R8 R2 R4 R6 R8
positive detections negative detections
1x8"
2x5"
3x4"
4x3"
simple source finding results
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Wallaby science meeting - Dec 2 2010
R2 R4 R6 R8 R2 R4 R6 R8
positive detections negative detections
1x8"
2x5"
3x4"
4x3"
simple source finding results
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R-band B-band Near-UV Far-UVINT optical GALEX ultra-violet
Stellar counterparts
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A 2192 A 963
Cube dimensions : 9.5 x 9.5 x 325 Mpc3
Synthesized beam size : 65 x 80 kpc2 x 80 km/s
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0.164 redsihft 0.224Cube dimensions: 9.5 x 9.5 x 85 Mpc3
surroundings of Abell 963
85 Mpc
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Examples of detections (based on pilot data)
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Wallaby science meeting - Dec 2 2010
Examples of detections (based on pilot data)
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detected HI masses
Determination of HI Mass Function and !HIrequires completion corrections : to be done...
144 HI detectionswith SDSS counterparts
(both clusters combined)
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MHI =
2x10
9
Relative HI gas mass fractions
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Colour-Magnitude diagram
: optical redshifts
: HI detections
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Wallaby science meeting - Dec 2 2010
Stacking HI spectra (based on pilot data)
Average HI mass: 2x10 M •&9~
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Wallaby science meeting - Dec 2 2010
Conclusions
• Expected rms achieved with the WSRT
• HI emission from >150 individual galaxies at Z#0.2
• Blind HI surveys uncover LSS not seen by SDSS
• Blue ‘BO-galaxies’ gas-poor wrt similar field galaxies
• !HI and HI-based TF at Z=0.2 expected soon
The HI-universe at Z#0.2 is under reach !