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Analysis of shape parameters of early-type lensing galaxies and testing the existence of dark matter haloes

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Analysis of shape parameters of early-type lensing galaxies and testing the existence of dark matter haloes

4th CosPa Meeting UMons

May 20, 2015

Judith Biernaux Groupe OrCA - AGO Université de Liège

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Dark matter halos

M87 NGC 4414

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• Lots of diffuse components (lensed arcs, …) • Parasite signal from the lensed images

Gravitational lensing images

B1422+231 SDSS0924+0219

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• Lots of diffuse components (lensed arcs, …) • Parasite signal from the lensed images

➡ Need to subtract that influence

Gravitational lensing images

B1422+231 SDSS0924+0219

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Gravitational lensing images

• Lots of diffuse components (lensed arcs, …) • Parasite signal from the lensed images

➡ Need to subtract that influence

➡ Deconvolution using MCS algorithm (Magain, Courbin & Sohy, 1998)

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Gravitational lensing images

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Gravitational lensing images

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Gravitational lensing images

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• Classical fit : minimizing a merit function in a p-dimensional space (p = # parameters)

➡ Local minima

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Independent measurement of each shape parameter is needed (ellipticity, PA, effective (half-light) radius)

• Classical fit : minimizing a merit function in a p-dimensional space (p = # parameters)

➡ Local minima

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Independent measurement of each shape parameter is needed (ellipticity, PA, effective (half-light) radius)

Effective (half-light) radius : linear

regression

• Classical fit : minimizing a merit function in a p-dimensional space (p = # parameters)

➡ Local minima

Effective radius

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Effective radius

Classical fit with n = 4

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Preliminary results

DM halo

baryonic DM, no halo no DM

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Conclusions

New light on galactic evolution, cosmology, …

• Need of a method to measure the exponent n of the Sérsic law • Need to study a larger sample - Euclid

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• Planetary nebulae (Romanowsky et al., 2003) no haloes ! • Simulations of merging disk galaxies (Dekel et al., 2005) haloes !

• X-ray emission (Memola et al., 2011) haloes ! • Stellar kinematics (Cappellari et al., 2015) no haloes !

Around elliptical galaxies ?

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Dark matter halos ?

Persic, Salucci and Stel, 1995

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• Planetary nebulae (Romanowsky et al., 2003)

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• Planetary nebulae (Romanowsky et al., 2003)

• Simulations of merging disk galaxies (Dekel et al., 2005)

Around elliptical galaxies ?

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• Planetary nebulae (Romanowsky et al., 2003)

• Simulations of merging disk galaxies (Dekel et al., 2005) • X-ray emission (Memola et al., 2011)

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Around elliptical galaxies ?

System (galaxy) With halo (SIE) Without halo (constant M/L)

MG0414+0534 33 30 HE0435-1223 2.6 2.9 RXJ0911+0551 200 186 SDSS0924+0219 5 6 PG1115+080 20 6 SDSS1138+0314 1.2 0.7 B1422+231 7 43

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Références

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