Terschelling 6 Jul 2005 Filippo Fraternali (University of Oxford) The gaseous halos of spiral...
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Transcript of Terschelling 6 Jul 2005 Filippo Fraternali (University of Oxford) The gaseous halos of spiral...
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
The gaseous halos of spiral galaxies
Filippo Fraternali1
James Binney1
Rense Boomsma2
Tom Oosterloo3
Renzo Sancisi2,4
1 Theoretical Physics - University of Oxford (UK)2 Kapteyn Astronomical Institute (NL)
3 ASTRON - Dwingeloo (NL)4 INAF - Osservatorio di Bologna (I)
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
Thin disk
Gas out-flow
Cold gas infall
Thin disk
Gas accretion
Inflow and outflow processes
1. Galactic fountain (Shapiro & Field 1976)- Winds, SN explosions- Gas circulation
2. Accretion from the IGM- Companions - minor mergers (Sancisi & Van der Hulst 1988)- Primordial gas (Oort 1970)
Study of the extra-planar (halo) gas
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
OutlineHI observations:
edge-on: NGC891slow rotation
non-edge-on: NGC2403slow rotation + inflow
other galaxies
Dynamical model:model descriptionapplication to NGC891 and NGC2403
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
NGC 891
. Distance: 9.5 Mpc
. Type: Sb/SBb
. Inclination ~ 90o
. LB = 8 x 1010 LO
. Non-interacting
. Very similar to the Milky Way
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
The gaseous halo of NGC891Total HI maps
Sancisi & Allen 1979 Swaters et al. 1997Oosterloo, Fraternali & Sancisi 2005
10 kpc
WSRT
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
Extra-planar gas in NGC 891
• Sancisi & Allen 1979 NH ≈ 5 1020 cm-2
• Swaters et al. 1997 NH ≈ 7 1019 cm-2
• Oosterloo et al. 2005 NH ≈ 1.7 1019 cm-2
• Sancisi & Allen 1979 NH ≈ 5 1020 cm-2
• Swaters et al. 1997 NH ≈ 7 1019 cm-2
• Oosterloo et al. 2005 NH ≈ 1.7 1019 cm-2
• Sancisi & Allen 1979 NH ≈ 5 1020 cm-2
• Swaters et al. 1997 NH ≈ 7 1019 cm-2
• Oosterloo et al. 2005 NH ≈ 1.7 1019 cm-2
200+ hours at the WSRT
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
NGC891: data cube
QuickTime™ and aVideo decompressor
are needed to see this picture.
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
NGC891: Low rotation of extra-planar gas
Fraternali 2005
vrot~15 km s-1 kpc-1
See also poster by G. Heald et al.
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
NGC 2403
.Distance: 3 Mpc
.Type: Sc
.Inclination ~ 62
.Non-interacting
.Very similar to M33
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
Extra-planar gas in non–edge-on galaxies
NGC2403: total HI map
Fraternali, van Moorsel, Sancisi, Oosterloo, AJ, 2002
Velocity fieldThin disc model
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
NGC2403: Extra-planar gas
Extra-planar gas
130 km/s
Forbidden gas
Fraternali, Oosterloo, Sancisi, van Moorsel 2001
Thin disc model
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
Extra-planar gas and accretion
8 kp
c107 Mo of H I
5 kpc
NGC2403
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
NGC2403: Non circular motions
Thin disc Extra-planar gas
V
Lagging haloThin disc
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
Non-circular motionspurerotationpure radialinflow
rotation + outflowrotation + inflow
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
Summary (observations) Extra-planar detected up to 15 kpc from plane
Rotation lower than the disc
High velocities (100-200 km s-1)
Global inflow motion
Link with star formation?
Evidence for accretion?
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
How common is halo gas? Halo gas (HI) found and studied in 7 galaxies:
NGC891, N2403, N6946, N253 (Boomsma et al. 2005), N4559 (Barbieri et al. 2005), UGC7321 (Matthews & Wood 2003), NGC2613 (Irwin & Chaves 2003).
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
NGC6946: Extra-planar gas and SF
Boomsma PhD 2005
WRST
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
How common is halo gas? Halo gas (HI) found and studied in 7 galaxies:
NGC891, N2403, N6946, N253 (Boomsma et al. 2005), N4559 (Barbieri et al. 2005), UGC7321 (Matthews & Wood 2003), NGC2613 (Irwin & Chaves 2003).
Hints of halo gas (HI) in other galaxies:NGC 5055 (Battaglia et al. 2005)
M33 (van der Hulst, private)
UGC 1281 (P. Kamphuis, PhD)
UGC 12632 (new WSRT observations)
HVCs in Milky Way (Wakker et al.)
HVCs in M83 and M51 (Miller & Bregman 2005)
HVCs in M31 (R. Braun et al.)
Ionised gas found and studied in several galaxies (e.g. Rand)
Origin: fountain and/or accretion?
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
Dynamical models
• A barotropic [p=p()] fluid in a gravitational field corotates (Poincaré, 1893)
• Hydrostatic models for non-barotropic fluid show gradient in rotation velocity but also high temperatures
(Barnabé, Ciotti, Fraternali, Sancisi, A&A, submitted)
Previous works:
• Galactic fountain: gas circulation (disc-halo-disc) (Shapiro & Field, ApJ 1976; Bregman, ApJ 1980)
• Ballistic models: disagreement between predicted gradient in rotation velocity and H data
(Collins, Benjamin & Rand, A&A 2002)
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
Dynamical model• Continuous flow of particles from the disc to the halo
• Initial conditions: distribution of kick velocities
• Potential: exponential discs + bulge + DM halo
• Integration in the (R,z) plane, then distribution along
• At each dt projection along the line of sight
• Stop at the first or second passage through the disc
• Pseudo-cube to be compared with HI data cube
QuickTime™ and aDV - PAL decompressor
are needed to see this picture.
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
Model constraint: vertical distribution
Vkick ~ 75 km s-1
Mhalo ~2 109 M
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
N891: inflow/outflowTravel times
Energy input <4 % of energy from SNe
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
NGC891: Lack of low angular momentum
Fast rotating gas
NEED FOR LOW ANGULAR MOMENTUM MATERIAL
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
NGC2403: lagging gas
Thin disc
Thick disc
60o
Vkick ~ 70 km s-1
Mhalo ~ 5 108 M
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
NGC2403: inflow/outflowThin disc gas
Extra-planar gas
Radial outflow
NEED FOR INFALLING MATERIAL
V
VR
Vz
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
Second-passage models
V
VR
Vz
V
VR
Vz
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
Summary (models) Models reproduce the vertical extent with reasonable energy
input (<4 % SN energy)
Failure in NGC2403: lack of inflow Need for accretion
Failure in NGC891: lack of low angular momentum Need for interactions or accretion
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
High Velocity Clouds
Complex AM 106 MO
d 8-10 kpcv 100 km s-1
Wakker et al. 2003; Wakker & Van Woerden 1997
Complex Cv 100 km s-1
If d 10 kpc M 107 MO
Low metallicity Z=0.1-0.3 solar(Tripp et at. 2003)
Forbidden gasv 100 km s-1
M 5 · 106 MO
Filamentv 80 km s-1
M 107 MO
Filippo Fraternali (University of Oxford) Terschelling 6 Jul 2005
Conclusions Extra-planar gas:
maybe common up to 10-15 kpc from the plane
Kinematics: Low rotation (gradient) + vertical motions (up to 100-200 km/s) + overall inflow
Evolution of spiral galaxies influenced both by:- Star formation (gas to the halo, to the outer parts...) - Accretion of cold material
Dynamical models: galactic fountains alone do not reproduce the kinematics of the extra-planar gas and require accretion from IGM