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HI Stacking:

Past, Present and Future. HI Pathfinder Workshop. Perth, February 2-4, 2011. Philip Lah. HI . Stacking. C. oadding the . HI 21-cm emission . from distant galaxies . using the galaxies’ known . optical positions.

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HI Stacking:






Presentation on theme: "HI Stacking:"— Presentation transcript:

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 MChengalur et al. 2001z = 0.06 Abell 3128ATCA 39 hrs 148 redshiftscoadded HI spectrum sensitive down to MHI ~9 108 MVerheijen et al. 2007z=0.19 Abell 2192 & z=0.21 Abell 963WSRT, 420 hrs total14 blue, field galaxies average MHI = 2109 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 MChengalur et al. 2001z = 0.06 Abell 3128ATCA 39 hrs 148 redshiftscoadded HI spectrum sensitive down to MHI ~9 108 MVerheijen et al. 2007z=0.19 Abell 2192 & z=0.21 Abell 963WSRT, 420 hrs total14 blue, field galaxies average MHI = 2109 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 MChengalur et al. 2001z = 0.06 Abell 3128ATCA 39 hrs 148 redshiftscoadded HI spectrum sensitive down to MHI ~9 108 MVerheijen et al. 2007z=0.19 Abell 2192 & z=0.21 Abell 963WSRT, 420 hrs total14 blue, field galaxies average MHI = 2109 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 MLah et al. 2009z = 0.37 Abell 370 GMRT ~34 hrs for all 324 galaxiesaverage MHI = (6.6 ± 3.5) ×109 Mfor the 105 blue galaxiesaverage MHI = (19.0 ± 6.5) ×109 MChang 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 MLah et al. 2009z = 0.37 Abell 370 GMRT ~34 hrs for all 324 galaxiesaverage MHI = (6.6 ± 3.5) ×109 Mfor the 105 blue galaxiesaverage MHI = (19.0 ± 6.5) ×109 MChang 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 MLah et al. 2009z = 0.37 Abell 370 GMRT ~34 hrs for all 324 galaxiesaverage MHI = (6.6 ± 3.5) ×109 Mfor the 105 blue galaxiesaverage MHI = (19.0 ± 6.5) ×109 MChang 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 MLah et al. 2009z = 0.37 Abell 370 GMRT ~34 hrs for all 324 galaxiesaverage MHI = (6.6 ± 3.5) ×109 Mfor the 105 blue galaxiesaverage MHI = (19.0 ± 6.5) ×109 MChang 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 ~

31010 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

)

xxyyz 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