Past Present and Future HI Pathfinder Workshop Perth February 24 2011 Philip Lah HI Stacking C oadding the HI 21cm emission from distant galaxies using the galaxies known optical positions ID: 556637
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Slide1
HI Stacking:
Past, Present and Future
HI Pathfinder WorkshopPerth, February 2-4, 2011
Philip LahSlide2
HI
Stacking
C
oadding the
HI 21-cm emission
from distant galaxies
using the galaxies’ known optical positions and redshiftsnoise decreases √N galaxies stackedSlide3
HI
Stacking
C
oadding the
HI 21-cm emission
from distant galaxies
using the galaxies’ known optical positions and redshiftsnoise decreases √N galaxies stackedSlide4
PastSlide5
HI
Stacking
Who
What
With
Result
Zwaan 2000 PhD
z = 0.18
Abell 2218
WSRT ~200 hrs
45 redshifts,
average
M
HI
= (5.3 ± 2.1) 108 MChengalur et al. 2001z = 0.06 Abell 3128ATCA 39 hrs 148 redshiftscoadded HI spectrum sensitive down to MHI ~9 108 MVerheijen et al. 2007z=0.19 Abell 2192 & z=0.21 Abell 963WSRT, 420 hrs total14 blue, field galaxies average MHI = 2109 M for 12 blue cluster , 32 red cluster and 22 red field galaxies – no HI detectionSlide6
HI
Stacking
Who
What
With
Result
Zwaan 2000 PhD
z = 0.18
Abell 2218
WSRT ~200 hrs
45 redshifts,
average
M
HI
= (5.3 ± 2.1) 108 MChengalur et al. 2001z = 0.06 Abell 3128ATCA 39 hrs 148 redshiftscoadded HI spectrum sensitive down to MHI ~9 108 MVerheijen et al. 2007z=0.19 Abell 2192 & z=0.21 Abell 963WSRT, 420 hrs total14 blue, field galaxies average MHI = 2109 M for 12 blue cluster , 32 red cluster and 22 red field galaxies – no HI detectionSlide7
HI
Stacking
Who
What
With
Result
Zwaan 2000 PhD
z = 0.18
Abell 2218
WSRT ~200 hrs
45 redshifts,
average
M
HI
= (5.3 ± 2.1) 108 MChengalur et al. 2001z = 0.06 Abell 3128ATCA 39 hrs 148 redshiftscoadded HI spectrum sensitive down to MHI ~9 108 MVerheijen et al. 2007z=0.19 Abell 2192 & z=0.21 Abell 963WSRT, 420 hrs total14 blue, field galaxies average MHI = 2109 M for 12 blue cluster , 32 red cluster and 22 red field
galaxies – no HI detectionSlide8
HI
Stacking
Who
What
With
Result
Lah et al. 2007
z = 0.24
Fujita Galaxies
GMRT ~48 hrs
121 redshifts,
average
M
HI = (2.26 ± 0.90) ×109 MLah et al. 2009z = 0.37 Abell 370 GMRT ~34 hrs for all 324 galaxiesaverage MHI = (6.6 ± 3.5) ×109 Mfor the 105 blue galaxiesaverage MHI = (19.0 ± 6.5) ×109 MChang et al. 2010z = 0.53 to 1.12 DEEP2 surveyGBT 15.3 hrsmeasured aggregate HI 21-cm emission from many unresolved galaxies in the ‘cosmic web’ΩHI = (5.5 ± 1.5) × 104 × (1/rb)Slide9
The
HI Gas Density
of the UniverseSlide10
HI Gas Density EvolutionSlide11
HI Gas Density Evolution
Zwaan et al. 2005
HIPASS
HI 21cm
Rao et al.
2006
DLAsfrom MgII absorptionNoterdaeme et al. 2009 &Prochaskaet al. 2005 DLAs
Lah et al. 2007
coadded
HI 21cmSlide12
HI Gas Density Evolution
Lah et al. 2007
coadded
HI 21cmSlide13
HI
Stacking
Who
What
With
Result
Lah et al. 2007
z = 0.24
Fujita Galaxies
GMRT ~48 hrs
121 redshifts,
average
M
HI = (2.26 ± 0.90) ×109 MLah et al. 2009z = 0.37 Abell 370 GMRT ~34 hrs for all 324 galaxiesaverage MHI = (6.6 ± 3.5) ×109 Mfor the 105 blue galaxiesaverage MHI = (19.0 ± 6.5) ×109 MChang et al. 2010z = 0.53 to 1.12 DEEP2 surveyGBT 15.3 hrsmeasured aggregate HI 21-cm emission from many unresolved galaxies in the ‘cosmic web’ΩHI = (5.5 ± 1.5) × 104 × (1/rb)Slide14
HI
Stacking
Who
What
With
Result
Lah et al. 2007
z = 0.24
Fujita Galaxies
GMRT ~48 hrs
121 redshifts,
average
M
HI = (2.26 ± 0.90) ×109 MLah et al. 2009z = 0.37 Abell 370 GMRT ~34 hrs for all 324 galaxiesaverage MHI = (6.6 ± 3.5) ×109 Mfor the 105 blue galaxiesaverage MHI = (19.0 ± 6.5) ×109 MChang et al. 2010z = 0.53 to 1.12 DEEP2 surveyGBT 15.3 hrsmeasured aggregate HI 21-cm emission from many unresolved galaxies in the ‘cosmic web’ΩHI = (5.5 ± 1.5) × 104 × (1/rb)Slide15
HI
Stacking
Who
What
With
Result
Lah et al. 2007
z = 0.24
Fujita Galaxies
GMRT ~48 hrs
121 redshifts,
average
M
HI = (2.26 ± 0.90) ×109 MLah et al. 2009z = 0.37 Abell 370 GMRT ~34 hrs for all 324 galaxiesaverage MHI = (6.6 ± 3.5) ×109 Mfor the 105 blue galaxiesaverage MHI = (19.0 ± 6.5) ×109 MChang et al. 2010z = 0.53 to 1.12 DEEP2 surveyGBT 15.3 hrsmeasured aggregate HI 21-cm emission from many unresolved galaxies in the ‘cosmic web’ΩHI = (5.5 ± 1.5) × 10-4 × (1/rb)Slide16
HI Gas Density EvolutionSlide17
HI Gas Density Evolution
Chang et al. 2010
HI emission cross-correlationSlide18
Hydrogen 21-cm Intensity Mapping at Redshift 0.8
Ω
HI = (5.5 ± 1.5) × 10-4 × (1/
rb
)
b
is the bias factor, the HI to optical galaxy relationship r is the stochasticity, the distribution of galaxies, how random is it theoretical constraints put rb in the range 0.5 to 2Slide19
Hydrogen 21-cm Intensity Mapping at Redshift 0.8
Ω
HI = (5.5 ± 1.5) × 10-4 × (1/
rb
)
b
is the bias factor, the HI to optical galaxy relationship r is the stochasticity, the distribution of galaxies, how random is it theoretical constraints put rb in the range 0.5 to 2Slide20
Hydrogen 21-cm Intensity Mapping at Redshift 0.8
Ω
HI = (5.5 ± 1.5) × 10-4 × (1/
rb
)
b
is the bias factor, the HI to optical galaxy relationship r is the stochasticity, the distribution of galaxies, how random is it theoretical constraints put rb in the range 0.5 to 2Slide21
HI Gas Density Evolution
Chang et al. 2010
HI emission cross-correlation
Effect of systematic uncertainty in ‘
rb
’ term (0.5 to 2)Slide22
HI
Stacking
Who
What
With
Result
Fabello et al. 2011
z < 0.05
ALFALFA Survey
Arecibo
drift scans
~5000 galaxies from SDSS
1833 "early-type" galaxies
HI content of a galaxy is not influenced by its bulgeSlide23
PresentSlide24
Challenges
Encountered
When
HI StackingSlide25
The
Telescope Primary Beam
and the
Galaxy
Spatial DistributionSlide26
Telescope
Gain
GMRT Primary Beam
Abell 370 galaxiesSlide27
Telescope
Gain
50%
beam level
Abell 370 galaxies
10%
beam levelGMRT Primary Beamuse a weighted averageSlide28
Galaxy Size
and the
Telescope Synthesis BeamSlide29
HI Galaxy SizeSlide30
HI Galaxy Size
with cosmological correction
uncorrected R
2
law
20 kpc HI mass ~10
9M Slide31
HI Galaxy Size
GMRT synthesis beam FWHMSlide32
HI Galaxy Size
GMRT synthesis beam FWHM
ASKAP synthesis beam FWHMSlide33
HI Galaxy Size
ASKAP synthesis beam FWHM
WSRT synthesis beam FWHM
GMRT synthesis beam FWHM
100 kpc
HI mass ~
31010 M Slide34
HI Galaxy Size
Beam Confusion
– problem mainly with companion galaxies and in outskirts of clustersSlide35
HI Velocity Width
and
Optical SelectionSlide36
HI velocity width
HI flux
velocity
HI flux
velocity
edge on disk
galaxyface on disk galaxySlide37
HI Velocity
Width
Assuming a random distribution of disk orientations: 13% of disk galaxies will have inclinations < 30° (face on)
50% of disk galaxies will have inclinations > 60° (
edge on
)
xxyyz z edge on diskgalaxiesface on disk galaxiesSlide38
HI Velocity
Width
HI selected galaxies biased towards face on – higher peak fluxSlide39
HI Velocity
Width
optical selection less effected by inclination bias
edge on systems – higher optical surface brightness Slide40
The End Result
The coadded HI velocity width of an optically selected sample of galaxies
will be larger than the coadded HI velocity width of a HI selected sample of similar galaxies
→
the HI flux of coadded optical samples will be spread over more frequency channelsSlide41
Optical Redshift Error
additionally
the coadded HI velocity width of an optically selected sample of galaxies will be further broadened
by the
random error
in the
optical redshiftSlide42
FutureSlide43
HI
coadding
with SKA PathfindersSlide44
EVLA
&
zCOSMOSSlide45
EVLA
z= 0 to 0.4Slide46
EVLA
EVLA
beam FWHM at1000 MHzHI z = 0.42
45 arcmin
EVLA
beam 10% level at1000 MHz HI z = 0.42 82 arcminz= 0 to 0.4Slide47
EVLA
~
65 per cent of zCOSMOS galaxies are star-forming, blue, disk-dominate galaxies (Mignoli et al.
2008)
n
z = 1723Slide48
EVLASlide49
EVLA
Examining volume spanned by zCOSMOS surveySlide50
EVLA
Examining volume spanned in a redshift binSlide51
EVLASlide52
EVLASlide53
WSRT - APERTIF
&
AGESSlide54
AGES
AGES - AGN and Galaxy Evolution Survey observed with
MMT Hectospec3 x 3 degree fieldRA 14h 32m DEC +34d 16mRujopakarn et al. 2010, AJ, 718, 1171
APERTIF 8 sq deg field of viewSlide55
AGES
n
z = 4825 (SF)
AGES - AGN and Galaxy Evolution Survey
observed with
MMT Hectospec
3 x 3 degree fieldRA 14h 32m DEC +34d 16mRujopakarn et al. 2010, AJ, 718, 1171APERTIF 8 sq deg field of viewSlide56
AGESSlide57
AGESSlide58
AGESSlide59
ASKAP - FLASH
&
WiggleZSlide60
FLASH
FLASH area = ~25500 deg
2FLASH obs time = 2 hrs / field
WiggleZ area = ~900 deg
2
WiggleZ n
z = 176,936No ASKAP pointings = 30+Slide61
FLASH
ASKAP
field of view
FLASH area = ~25500 deg
2
FLASH obs time = 2 hrs / field
WiggleZ area = ~900 deg2WiggleZ nz = 176,936No ASKAP pointings = 30+Slide62
FLASH
n
z = 176,936
stacking data from many fields – i.e. coadding many HI spectra each observed for 2 hoursSlide63
FLASHSlide64
FLASHSlide65
FLASH
HI mass estimated from SFRSlide66
FLASH
HI mass estimated from SFR
Requires at least 1200 hrs(30+ fields)Slide67
ASKAP - Deep
&
WiggleZSlide68
Deep
ASKAP
field of view~6 deg by ~6 degSlide69
Deep
n
z = 5491Slide70
DeepSlide71
DeepSlide72
Deep
HI mass estimated from SFRSlide73
Deep
HI mass estimated from SFRSlide74
MeerKAT - LADUMA
&
CDFSSlide75
LADUMA
40 x 40 arcmin Slide76
LADUMA
160 x 160 arcmin Slide77
LADUMA
160 x 160 arcmin
FWHM
beam z = 0
beam z = 0.58
beam z=1.42Slide78
LADUMA
n
z = 3151
estimate ~
65 per cent
star-forming
, galaxiesSlide79
LADUMASlide80
LADUMASlide81
LADUMASlide82
LADUMASlide83
SKASlide84
SKASlide85
SKASlide86
SKASlide87
SKASlide88
SKASlide89
ConclusionSlide90
Past
→ many results from HI stacking in both nearby and higher redshift galaxy samples; results have been improving as larger optical redshift surveys have been combined with deeper radio observations
Present
→ challenges encountered when HI stacking include the effect of the telescope primary and synthesis beams, of the inclination of galaxies and redshift error on the HI velocity width Future → optical redshift suveys exist currently that can be used with the SKA pathfinders for HI stacking; the SKA could make useful observations out to redshift z = 6 if sufficiently large redshift surveys exist at that timeConclusionSlide91
Past
→ many results from HI stacking in both nearby and higher redshift galaxy samples; results have been improving as larger optical redshift surveys have been combined with deeper radio observations
Present
→ challenges encountered when HI stacking include the effect of the telescope primary and synthesis beams, of the inclination of galaxies and redshift error on the HI velocity width Future → optical redshift suveys exist currently that can be used with the SKA pathfinders for HI stacking; the SKA could make useful observations out to redshift z = 6 if sufficiently large redshift surveys exist at that timeConclusionSlide92
Past
→ many results from HI stacking in both nearby and higher redshift galaxy samples; results have been improving as larger optical redshift surveys have been combined with deeper radio observations
Present
→ challenges encountered when HI stacking include the effect of the telescope primary and synthesis beams, of the inclination of galaxies and redshift error on the HI velocity width Future → optical redshift suveys exist currently that can be used with the SKA pathfinders for HI stacking; the SKA could make useful observations out to redshift z = 6 if sufficiently large redshift surveys exist at that timeConclusion