Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk Do planetary nebulae indicate a lack of dark matter 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/ Are PNe in ellipticals young? and Ewa ŁOKAS (CAMK, Warsaw) MNRAS, submitted, astro-ph/

Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk Planetary Nebulae: Tracers at 1-3R eff N3379 [O III ] 5007 A

Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk PN velocity dispersions are low Mendez et al. 01 N4697 Romanowsky et al. 03 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/L sun log (M/L)/(M/L sun ) Marinoni & Hudson 02 Predicted & observed M/L Romanowsky et al 03 33 M/L = 33?

Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk 1) Do ellipticals have normal contents of dark matter? ellipticals thought to be formed by mergers, mainly of spirals Toomre 77 Mamon 92, 00; Helsdon & Ponman 03 Springel 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 major mergers of spiral galaxies embedded in dark matter halos Cox 04, PhD thesis

Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk Velocity dispersions no DM (R03) with DM (R03) DM all stars young stars Dekel et al 05

Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk 2) What causes this discrepancy between 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 Jeans eq. Power-law solutions to Jeans equations

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 (2) velocity anisotropy tracer density slope

Gary Mamon, 2 July 2005, PNe as astronomical tools, 5 R 2 R e isotropic NFW anisotropic Navarro+04 isotropic Navarro+04 Mamon & Łokas 05b, MNRAS subm Velocity dispersion vs anisotropy & dark halo model

Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk Mamon & Łokas 05b, MNRAS submitted Effects on M/L at virial radius

Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk 3D profiles from merger simulations

Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk out of equilibrium! mass underestimated by ≈ 40% Out of Jeans equilibrium? non-stationarity? non-sphericity

Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk Effects of triaxiality face-on edge-on face-on

What M/Ls were found by Romanowsky et al. 03? Published M/L Mamon & Łokas 05b, MNRAS submitted f bary >  b /  m best concentration parameters

3) Are observed PNe in ellipticals young?

Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk Young stars have lower velocity dispersions no DM (R03) with DM (R03) DM all stars young stars Dekel et al 05

Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk 4th order (h 4 ) moments intermediate radii outer radii = all stars= young stars young stars have large |h 4 | as PNe in galaxies appear to

Gary Mamon, 2 July 2005, PNe as astronomical tools, Gdansk PNe vs old globular clusters GCs have much higher outer velocity dispersions! Bergond, Zepf et al. 05 but  GC <  stars GCs Côté et al. 01 stars M87

PN luminosity function NGC 4697 Mendez et al. 01 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 recent major mergers sufficient bright PN formation with low enough star formation? Alternative: gas-rich dark dwarfs fall onto ellipticals, tidal compression  smooth accretion star 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 PNeaccretion?