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H I in galaxies from z = 0.002 to z = 0.2. Thijs van der Hulst Kapteyn Astronomical Institute University of Groningen. Kapteyn astronomical institute. Open Questions. When and how quickly did the gas settle in the dark matter potential wells - PowerPoint PPT Presentation
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HI in galaxies from z = 0.002 to z = 0.2
Thijs van der Hulst
Kapteyn Astronomical InstituteUniversity of Groningen
Kapteyn astronomical institute
Open Questions
- When and how quickly did the gas settle in the dark matter potential wells
- Where and how did gas get converted into stars
- When and how did the merging process develop
- What is the importance of gas accretion versus merging
Radiotelescopes can trace the neutral gas extremely well( to go beyond z = 0.2 we need SKA )
COLD GAS HI observations local universe
- Extended HI disks with outer spiral structure
- Large majority of disks WARPED and LOPSIDED
- Lumpy HI structures (clouds, tails, filaments) around galaxies
Result of recent minor mergers and accretion?
- Large reservoirs extra-planar gas
Sancisi et al. A&A Rev., 2008
WARPS
LOPSIDEDNESS
WSRT 1976
HI WSRT
HI VLA
3x108 Mʘ
HI masses in outer structures 108 - 109 Mʘ
optical NGC 5055 neutral hydrogen WSRT
same scale Battaglia et al. 2005
EXTENDED HI (note the spiral structure)
NGC 5055 neutral hydrogen WSRT
same scale Battaglia et al. 2005
EXTENDED HI (spiral arms) GALEX
NGC 6946optical neutral hydrogen
same scale
WSRT
Boomsma et al. 2007
neutral hydrogen
same scale
Boomsma et al. 2007
WSRTDeep B-band
A. Ferguson 2007
Some star formation also in outer disk
NGC 6946
HIGH VELOCITYCLOUDS( total amount ~3 x 108 Mʘ )
NGC 6946Accretion?
Boomsma et al. 2007
HI map WSRT
NGC 2403
HI VLA
Fraternali et al. 2001
modelthin disk
Anomalous gas
3x108 Mʘ
NGC 891 Anomalous HI ~ 1 x 108 Mʘ
Fraternali, 2007
Extra-planar HI
MILKY WAY, NGC 891, NGC 2403M 31, NGC 4559, NGC 253, UGC 7321, NGC 5775, NGC 6946
Emerging picture:
HI disk
- extended with outer spiral structure - warped - lopsided - porous
Extra-planar HI (high velocity clouds)
ACCRETION?
Local UniverseHI detection limits:Column densities 1 x 1019 cm-2
Accreted HI 107 - 109 Mʘ
Time scales 108 - 109 yrsGalaxy fraction 25 - 50 %Accretion rate 0.1 - 0.5 Mʘ / yr
Masses 1 x 106 Mʘ
SUMMARY
4. Cold gas lumpy accretion at a mean rate of 0.1 – 0.5 Mʘ / yr
25 – 50 % of all galaxies accrete lumps of gas of 107-9 Mʘ
1. Spiral structure and star formation in outer HI disks
2. Most galaxies warped and lopsided
3. Large reservoirs of extra-planar HI
HI near the center of the Virgo cluster
Oosterloo & van Gorkom, 2005, A&A 437, 19
NGC 4388
3.8 x 108 Mʘ
The Amazing NGC 7426
- ‘Normal Elliptical- Two tails, 185, 125 h-1 kpc in length!- 4 x 109 h-2 Mʘ
- NHI (min) = 1019 cm-2
- Tails aligned with Pisces-Perseus super cluster structure
>300 h-1 kpc
Schiminovich, van Gorkom et al.
Verheijen, van Gorkom et al. 2007
Present state of the art: imaging HI emission out to z = 0.2
240 hour integration with WSRT
SKA goals for deep fields:
- get to MHI* galaxies out to z = 2
- detect HVC mass objects to z = 0.2
- detect dwarf galaxies to z = 0.5
redshift lookback
time
HI mass limit (Msun)
# detections HI mass limit (Msun)
# detections
Gyr t = 360 h t = 1000 h
0.5 – 1.0 5.0 – 7.7 5.0 x 108 1.6 x 106 3.0 x 108 2.4 x 106
1.0 – 1.5 7.7 – 9.3 1.3 x 109 1.8 x 106 7.9 x 108 2.7 x 106
1.5 – 2.0 9.3 – 10.3 2.7 x 109 1.9 x 106 1.6 x 109 2.7 x 106
2.0 – 2.5 10.3 – 11.0 4.8 x 109 1.7 x 106 2.9 x 109 2.5 x 106
2.5 – 3.0 11.0 – 11.5 7.8 x 109 1.6 x 106 4.7 x 109 2.3 x 106
3.0 – 3.5 11.5 – 11.8 1.2 x 1010 1.4 x 106 7.3 x 109 2.0 x 106
3.5 – 4.0 11.8 – 12.1 1.8 x 1010 1.2 x 106 1.1 x 1010 1.8 x 106
4.0 – 4.5 12.1 – 12.3 2.7 x 1010 1.0 x 106 1.6 x 1010 1.5 x 106
Number of galaxies detectable as a function of redshift per square degree
redshift lookback
time
HI mass limit (Msun)
# detections HI mass limit (Msun)
# detections
Gyr t = 360 h t = 1000 h
0.5 – 1.0 5.0 – 7.7 3.6 x 109 3.8 x 105 2.1 x 109 5.6 x 105
1.0 – 1.5 7.7 – 9.3 9.3 x 109 4.5 x 105 5.6 x 109 6.5 x 105
1.5 – 2.0 9.3 – 10.3 1.9 x 1010 4.3 x 105 1.1 x 1010 6.4 x 105
2.0 – 2.5 10.3 – 11.0 3.4 x 1010 4.0 x 105 2.0 x 1010 5.8 x 105
2.5 – 3.0 11.0 – 11.5 5.5 x 1010 3.6 x 105 3.3 x 1010 5.2 x 105
Phase-1 SKA: Number of galaxies / sq. deg. as a function of redshift
Redshift Frequency Tsys Angular Resolution
Linear Resolution
SB -dimming
Luminosity Distance
Lookback time
HI mass limit
MHz K arcsec kpc Gpc Gyr Msun
0.2 1183.67 50.4 0.52 1.7 0.796 0.972 2.41 6.1x108
0.5 946.94 51.4 0.65 4.0 1.486 2.825 5.02 8.7x108
2.0 710.20 53.8 0.87 7.0 3.026 6.640 7.73 2.7x109
2.5 568.16 57.5 1.09 9.3 4.000 11.02 9.32 7.2x109
2.0 473.47 62.7 1.31 11.1 4.796 15.75 10.32 1.5x1010
2.5 405.83 69.6 1.52 12.5 5.469 20.72 11.00 2.6x1010
3.0 355.10 78.3 1.74 13.6 6.052 25.87 11.48 4.3x1010
3.5 315.64 89.3 1.96 14.6 6.566 31.15 11.83 6.7x1010
Detection limits for SKA for t = 12 hours
Phase-1 SKA Detection limits for t = 12 hours
Redshift Frequency Tsys Angular Resolution
Linear Resolution
SB -dimming
Luminosity Distance
Lookback time
HI mass limit
MHz K arcsec kpc Gpc Gyr Msun
1.0 710.20 53.8 0.87 7.0 3.026 6.640 7.73 1.9x1010
1.5 568.16 57.5 1.09 9.3 4.000 11.02 9.32 5.1x1010
2.0 473.47 62.7 1.31 11.1 4.796 15.75 10.32 1.0x1011
2.5 405.83 69.6 1.52 12.5 5.469 20.72 11.00 1.8x1011
3.0 355.10 78.3 1.74 13.6 6.052 25.87 11.48 3.0x1011