%0 Generic %1 clauwens2014evidence %A Clauwens, Bart %A Schaye, Joop %A Franx, Marijn %D 2014 %K early-type imf nearby variability %T Is the evidence for a variable initial mass function from ATLAS3D robust? %U http://arxiv.org/abs/1406.0854 %X The ATLAS3D Survey has reported strong evidence for a non-universal stellar initial mass function (IMF) and for a trend of the IMF with the effective stellar velocity dispersion of early type galaxies (ETGs) (Cappellari et al. 2012). The ATLAS3D Survey consists of detailed Integral Field Spectroscopy of 260 ETGs closer than 42 Mpc. Cappellari et al. infer the IMF by comparing mass measurements derived from fitting the kinematic data with measurements derived from fitting the spectral energy distribution. Here we investigate possible systematic errors and biases that could affect their conclusions. We show that part of the reported trend between IMF and velocity dispersion is caused by a selection effect on Heta absorption. Apart from an IMF trend with velocity dispersion, we also find an IMF trend with distance, but no correlation between nearest neighbour ETGs as would be expected if the dependence on distance would reflect an environmental dependence. Part of the IMF trend with velocity dispersion can be traced back to colour-dependent calibration issues with the surface brightness fluctuation distances of Tonry et al. (2001) and Mei et al. (2007). There is no IMF-dispersion trend for galaxies with distances larger than 25 Mpc. The ATLAS3D Survey appears to be incomplete for masses lower than 10^10.3 solar masses. Restricting the analysis to the kinematic mass range M > 10^10.3 solar masses completely removes the IMF-dispersion trend. Our findings strongly suggest that some of the trends between IMF and galaxy properties reported by ATLAS3D are unphysical and caused by systematics.

@misc{clauwens2014evidence, abstract = {The ATLAS3D Survey has reported strong evidence for a non-universal stellar initial mass function (IMF) and for a trend of the IMF with the effective stellar velocity dispersion of early type galaxies (ETGs) (Cappellari et al. 2012). The ATLAS3D Survey consists of detailed Integral Field Spectroscopy of 260 ETGs closer than 42 Mpc. Cappellari et al. infer the IMF by comparing mass measurements derived from fitting the kinematic data with measurements derived from fitting the spectral energy distribution. Here we investigate possible systematic errors and biases that could affect their conclusions. We show that part of the reported trend between IMF and velocity dispersion is caused by a selection effect on H\b{eta} absorption. Apart from an IMF trend with velocity dispersion, we also find an IMF trend with distance, but no correlation between nearest neighbour ETGs as would be expected if the dependence on distance would reflect an environmental dependence. Part of the IMF trend with velocity dispersion can be traced back to colour-dependent calibration issues with the surface brightness fluctuation distances of Tonry et al. (2001) and Mei et al. (2007). There is no IMF-dispersion trend for galaxies with distances larger than 25 Mpc. The ATLAS3D Survey appears to be incomplete for masses lower than 10^10.3 solar masses. Restricting the analysis to the kinematic mass range M > 10^10.3 solar masses completely removes the IMF-dispersion trend. Our findings strongly suggest that some of the trends between IMF and galaxy properties reported by ATLAS3D are unphysical and caused by systematics.}, added-at = {2014-06-05T09:56:17.000+0200}, author = {Clauwens, Bart and Schaye, Joop and Franx, Marijn}, biburl = {https://www.bibsonomy.org/bibtex/2c7ad8ea445db20d3b9faadcec457a0c7/miki}, description = {[1406.0854] Is the evidence for a variable initial mass function from ATLAS3D robust?}, interhash = {0c96dab2ccad6b8816d0e77f69f80dfc}, intrahash = {c7ad8ea445db20d3b9faadcec457a0c7}, keywords = {early-type imf nearby variability}, note = {cite arxiv:1406.0854Comment: 12 pages, 10 figures}, timestamp = {2014-06-05T09:56:26.000+0200}, title = {Is the evidence for a variable initial mass function from ATLAS3D robust?}, url = {http://arxiv.org/abs/1406.0854}, year = 2014 }