the faint end ….

…. in neutral gas

“luminous”

Radio spectroscopy

Upper limits to space density of intergalactic HI Clouds

# Clouds /Mpc3

/decade

MHI

-

-

-

-

-

Volu

me

(Mp

c3)

Volume for each survey that was

sensitive to MHI

MHI

Upper limits to space density of intergalactic HI Clouds

# Clouds /Mpc3

/decade

MHI

HI in Galaxies

Upper limits to space density of intergalactic HI Clouds

# Clouds /Mpc3

/decade

MHI

Lo & Sargent (1979) M81, CVn, NGC 1023 Groups

Log MHI 6.8 6.6 7.9 7.8 7.7 8.1 Mpg -8.7 -12.3 -11.5 -13.1 -15.2 –15.5

MHI /L 18 0.4 15 3 0.4 1.3

… the writing is on the wall…

(… and in the literature…)

more HI in M96 than the Ring

(Schneider etal 1989)

Giovanelli, Haynes, Chengalur

“Virgo HI Cloud”

HI Mass Function: (dashed curve)

Felton 1985, Luminosity FunctionF-T for MHI/L(L)

HI Content according to galaxy mass

Integral HI mass content:

7.0x107 Mo Mpc-3

(HIMF faint end slope: = -1.28 )

Integral HI mass content:

6.1x107 Mo Mpc-3

( faint end slope: = -1.3 )

Parkes HIPASS results (2003):

(1990)

… what else in the meanwhile…

Relation of Galactic High Velocity Clouds to IGM…

… HVCs mostly within 200 kpc (Zwaan 2000, thesis)

HIPark – a parked Parkes survey

Goals: ultra sensitive to low column densities

How sensitive ?… optically thin at the Lyman limit

exercise in observational techniques … rfi, passband calibration, …

good match to long maintenance periods

diffuse clouds in diffuse clouds in LG LG

& Milky Way halo& Milky Way halo

HI Park proposers…

• Briggs• Barnes• de Blok• Freeman

• Gibson• Korbalski• Reynolds• Staveley-Smith• Zwaan

Progess: 25 days observations – John Reynolds

extragalactic preview – Jackie Cooper

CIVMgII/ Lyman limit(CII, FeII, SiII, …)

MOTIVE ? QSO absorption line interception cross sections

Z=3Ly break galaxy

DLADLA

12 14 18 20 22

HI Column density distribution function Petijean etal 1993

Log f(NHI)

-10

-15

-20

Log NHI

Number of interceptions in range: N to N+dN

f(N) dN /unit Z

Lyforest

IGM DLACIV

LL > 1

HI Map of M81 Group

Yun, Ho & Lo 1994

M81

M82

NGC 3077

NGC 3344

HIPARK Goal…

Sensitivity:

to achieve 6 < 3 x 1017 cm-2

need ~ 6 hours of integration per beam

Drift scan: 15’ beam transits in ~ 1 minute

~360 transits

Barnes et al

Multibeam !!!

1x

4x

3x

Feed orientation for drift scans

Path of Survey Strip:

GalacticCoords

Limits ontiny massesin Sculptor…

3x104 dMpc2

solar masses

Dcloud >1 kpc at 250 kpc

… to fill beam

03:34

05:56

R.A.

2200 km/s 0

FORNAX

Dec –32d53’

20:36

22:55

R.A.

2200 km/s 0

Dec –32d53’

Sculptor

(Putman et al)

22:55

01:14

R.A.

2200 km/s 0

SCULPTOR

Dec –32d53’

MagellanicStream

(Putman et al)

DEEPCentaurusSurvey

(Disney et al)

22:55

01:14

R.A.

2200 km/s 0

Dec –32d53’

Conclusions:

Early Low mass halos Star Formation ISM Lost

Late Low mass halos never capture gas, (No Star

Formation)

Large mass halos Star Formation

Galaxies

No Intergalactic Neutral Hydrogen Clouds at Z=0

… faint end still not known… ATA… SKA

(no I.G. HI clouds…)

RA

Velo

city

-500

0

1100Sun up !

RA

Velo

city

-500

0

1100

Right Ascension

Velo

city

0

-500

2800One Day – One Beam

RA

Velo

city

-500

0

1100 km/s

Galactic Plane crossing: L ~ 250o

RA

Velo

city

-500

0

1100

RA

Velo

city

-500

0

1100