Do planetary nebulae indicate a lack of dark matter in elliptical galaxies?
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Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk
Do planetary nebulae indicate Do planetary nebulae indicate a a lack of dark matterlack of dark matter in elliptical galaxies?in elliptical galaxies?
with
Avishai DEKEL (HU, Jerusalem), Felix STOEHR (IAP, Paris),TJ COX (Harvard), Greg NOVAK & Joel PRIMACK (UC Santa Cruz)Nature, accepted, astro-ph/0501622
Are PNe in ellipticals Are PNe in ellipticals youngyoung??
and
Ewa ŁOKAS (CAMK, Warsaw)MNRAS, submitted, astro-ph/0405491
Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk
Planetary Nebulae: Tracers at 1-3RPlanetary Nebulae: Tracers at 1-3Reffeff
N3379
[OIII]
5007 A
Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk
PN velocity dispersions are lowPN velocity dispersions are low
Mendez et al. 01
N4697
Romanowsky et al. 03
DM
DM
DM
no DM
no DM
no DM
are Ellipticals naked?
Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk
critical density Universe
universal M/L=387
log L/Lsun
log
(M/L
)/(M/L
sun)
Marinoni & Hudson 02
Predicted & observed M/LPredicted & observed M/L
Romanowsky et al 033
M/L = 33?
Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk
1) Do ellipticals have normal 1) Do ellipticals have normal contents of dark matter?contents of dark matter?
ellipticals thought to be formed by mergers, mainly of spirals Toomre 77
Mamon 92, 00; Helsdon & Ponman 03Springel et al. 01; Lanzoni et al. 05
spirals have dark matter halos Sofue & Rubin 02
Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk
Simulations of Simulations of major mergers of spiral galaxiesmajor mergers of spiral galaxies embedded in dark matter halos embedded in dark matter halos
Cox 04, PhD thesis
Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk
Velocity dispersionsVelocity dispersions
no DM (R03)
with DM (R03)
DM
all starsyoung stars
Dekel et al 05
Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk
2) What causes this discrepancy2) What causes this discrepancybetween between
kinematical & dynamical modelling?kinematical & dynamical modelling?
kinematical modelling no dark matter
dynamical modelling normal dark matter
Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk
Dekel et al. 05, Nature in press
€
d νσ r2
( )
dr+ 2β
rνσ r
2 = −νGM
r2= −ν
v circ2
rJeans eq.
€
ρtracer ∝ r−α
ρ total ∝ r−η ⇒ σ r ∝ vcirc ∝ r
1−η / 2
Power-law solutions to Jeans Power-law solutions to Jeans equationsequations
Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk
= tracer density slope
= dark matter density slope
realistic outer slopes: + > 5
or los
Power-law solutions to Jeans equations Power-law solutions to Jeans equations (2)(2)
velocity anisotropy tracer density slope
Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk
@ 5 Re
@ 2 Re
isotropic NFW
anisotropic Navarro
+04isotropic Navarro
+04
€
los(5Re )∝ Υ(rvir )[ ]1/ 8
Mamon & Łokas 05b, MNRAS subm
€
Υ(rvir )∝ σ los(5Re )[ ]8
Velocity dispersion vs Velocity dispersion vs anisotropy & dark halo modelanisotropy & dark halo model
Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk
Mamon & Łokas 05b, MNRAS submitted
Effects on M/L at virial radiusEffects on M/L at virial radius
Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk
3D profiles from merger simulations3D profiles from merger simulations
Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk
€
MJeans(r) =r vr
2
Gα + γ − 2β( )
€
γ=−d ln v r
2
d ln r
out of equilibrium!
mass underestimatedby ≈ 40%
Out of Jeans equilibrium?Out of Jeans equilibrium?
non-stationarity?
non-sphericity
Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk
Effects of Effects of triaxialitytriaxiality
face-onedge-on
edge-onface-on
What M/Ls were found by Romanowsky et al. 03?
Published M/L
Mamon & Łokas 05b, MNRAS submitted
fbary > b/ m
best
conc
entra
tion
para
met
ers
Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk
Young stars have lower velocity Young stars have lower velocity dispersionsdispersions
no DM (R03)
with DM (R03)
DM
all starsyoung stars
Dekel et al 05
Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk
4th order (h4th order (h44) moments) moments
intermediate radii
out
er
rad
ii
= all stars = young stars
young stars have large |h4| as PNe in galaxies appear to
Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk
PNe vs old globular clustersPNe vs old globular clusters
GCs have much higher outer velocity dispersions!Bergond, Zepf et al. 05
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
but GC < stars
GCs
Côté et al. 01
stars
M87
PN luminosity function
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
NGC 4697
Mendez et al. 01
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Marigo et al. 04
young ( 0.8 Gyr) PNe
Possible solutions for young bright PNe in ellipticals
One solution: blue stragglers Ciardullo et al. 05
very low recent star formation in ellipticals
universal PNLF (Es & SMC) Ciardullo et al. 89
young PNe?
} no recentmajor mergers
sufficient bright PN formation with low enough star formation?
Alternative: • gas-rich dark dwarfs fall onto ellipticals, • tidal compression
smooth accretionstar formation universal rate
Conclusions
Merger simulations of spirals embedded in DM yield remnants that reproduce low PN vel. dispersions
consistent with CDM scenario
Spherical kinematical modelling is not fully adequate
Kinematics of young stars in merger remnants
Low velocity dispersion produced by:radial anisotropy steep tracer density viewing oblate ellipticals face-on
(weakly) favors young PNe accretion?
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