@misc{ smith2014variations,
  abstract = {I present a comparison between published dynamical (ATLAS3D) and
spectroscopic (Conroy & van Dokkum) constraints on the stellar initial mass
function (IMF) in early-type galaxies, using the 34 galaxies in common between
the two works. Both studies infer an average IMF mass factor $α$ (the
stellar mass relative to a Kroupa-IMF population of similar age and
metallicity) greater than unity, i.e. both methods favour an IMF which is
heavier than that of the Milky Way, on average over the sample. However, on a
galaxy-by-galaxy basis, there is no correlation between $α$ inferred from
the two approaches. I investigate how the two estimates of $α$ are
correlated systematically with the galaxy velocity dispersion, $σ$, and
with the Mg/Fe abundance ratio. The spectroscopic method, based on the
strengths of metal absorption lines, yields a correlation only with metal
abundance ratios: at fixed Mg/Fe, there is no residual correlation with
$σ$. The dynamical method, applied to exactly the same galaxy sample,
yields the opposite result: the IMF variation correlates only with dynamics,
with no residual correlation with Mg/Fe after controlling for $σ$. Hence
although both methods indicate a heavy IMF on average in ellipticals, they lead
to incompatible results for the systematic trends, when applied to the same set
of galaxies. Although other explanations are possible, the sense of the
disagreement suggests that one (or both) of the methods has not accounted fully
for the main confounding factors, i.e. element abundance ratios or dark matter
contributions.},
  added-at = {2014-03-26T09:52:56.000+0100},
  author = {Smith, Russell J.},
  biburl = {http://www.bibsonomy.org/bibtex/2aa2be4d56029b8107e716d7c4f18ab90/miki},
  description = {[1403.6114] Variations in the initial mass function in early-type galaxies: A critical comparison between dynamical and spectroscopic results},
  interhash = {a8f54e72e5abc6201cfddd2bf11192e6},
  intrahash = {aa2be4d56029b8107e716d7c4f18ab90},
  keywords = {early-type galaxy imf variation},
  note = {cite arxiv:1403.6114Comment: Submitted to MNRAS},
  title = {Variations in the initial mass function in early-type galaxies: A
  critical comparison between dynamical and spectroscopic results},
  url = {http://arxiv.org/abs/1403.6114},
  year = {2014}
}

{"_id":{"_str":"537c54bbb3aa042605005d68"},"__v":0,"authorIDs":[],"author_short":["Smith, R.<nbsp>J."],"bibbaseid":"smith-variationsintheinitialmassfunctioninearlytypegalaxiesacriticalcomparisonbetweendynamicalandspectroscopicresults-2014","bibdata":{"downloads":0,"keyword":["early-type galaxy imf variation"],"bibbaseid":"smith-variationsintheinitialmassfunctioninearlytypegalaxiesacriticalcomparisonbetweendynamicalandspectroscopicresults-2014","urls":{"Paper":"http://arxiv.org/abs/1403.6114"},"role":"author","year":"2014","url":"http://arxiv.org/abs/1403.6114","type":"misc","title":"Variations in the initial mass function in early-type galaxies: A critical comparison between dynamical and spectroscopic results","note":"cite arxiv:1403.6114Comment: Submitted to MNRAS","keywords":"early-type galaxy imf variation","key":"smith2014variations","intrahash":"aa2be4d56029b8107e716d7c4f18ab90","interhash":"a8f54e72e5abc6201cfddd2bf11192e6","id":"smith2014variations","description":"[1403.6114] Variations in the initial mass function in early-type galaxies: A critical comparison between dynamical and spectroscopic results","biburl":"http://www.bibsonomy.org/bibtex/2aa2be4d56029b8107e716d7c4f18ab90/miki","bibtype":"misc","bibtex":"@misc{ smith2014variations,\n abstract = {I present a comparison between published dynamical (ATLAS3D) and\r\nspectroscopic (Conroy & van Dokkum) constraints on the stellar initial mass\r\nfunction (IMF) in early-type galaxies, using the 34 galaxies in common between\r\nthe two works. Both studies infer an average IMF mass factor $α$ (the\r\nstellar mass relative to a Kroupa-IMF population of similar age and\r\nmetallicity) greater than unity, i.e. both methods favour an IMF which is\r\nheavier than that of the Milky Way, on average over the sample. However, on a\r\ngalaxy-by-galaxy basis, there is no correlation between $α$ inferred from\r\nthe two approaches. I investigate how the two estimates of $α$ are\r\ncorrelated systematically with the galaxy velocity dispersion, $σ$, and\r\nwith the Mg/Fe abundance ratio. The spectroscopic method, based on the\r\nstrengths of metal absorption lines, yields a correlation only with metal\r\nabundance ratios: at fixed Mg/Fe, there is no residual correlation with\r\n$σ$. The dynamical method, applied to exactly the same galaxy sample,\r\nyields the opposite result: the IMF variation correlates only with dynamics,\r\nwith no residual correlation with Mg/Fe after controlling for $σ$. Hence\r\nalthough both methods indicate a heavy IMF on average in ellipticals, they lead\r\nto incompatible results for the systematic trends, when applied to the same set\r\nof galaxies. Although other explanations are possible, the sense of the\r\ndisagreement suggests that one (or both) of the methods has not accounted fully\r\nfor the main confounding factors, i.e. element abundance ratios or dark matter\r\ncontributions.},\n added-at = {2014-03-26T09:52:56.000+0100},\n author = {Smith, Russell J.},\n biburl = {http://www.bibsonomy.org/bibtex/2aa2be4d56029b8107e716d7c4f18ab90/miki},\n description = {[1403.6114] Variations in the initial mass function in early-type galaxies: A critical comparison between dynamical and spectroscopic results},\n interhash = {a8f54e72e5abc6201cfddd2bf11192e6},\n intrahash = {aa2be4d56029b8107e716d7c4f18ab90},\n keywords = {early-type galaxy imf variation},\n note = {cite arxiv:1403.6114Comment: Submitted to MNRAS},\n title = {Variations in the initial mass function in early-type galaxies: A\r\n critical comparison between dynamical and spectroscopic results},\n url = {http://arxiv.org/abs/1403.6114},\n year = {2014}\n}","author_short":["Smith, R.<nbsp>J."],"author":["Smith, Russell J."],"added-at":"2014-03-26T09:52:56.000+0100","abstract":"I present a comparison between published dynamical (ATLAS3D) and spectroscopic (Conroy & van Dokkum) constraints on the stellar initial mass function (IMF) in early-type galaxies, using the 34 galaxies in common between the two works. Both studies infer an average IMF mass factor $α$ (the stellar mass relative to a Kroupa-IMF population of similar age and metallicity) greater than unity, i.e. both methods favour an IMF which is heavier than that of the Milky Way, on average over the sample. However, on a galaxy-by-galaxy basis, there is no correlation between $α$ inferred from the two approaches. I investigate how the two estimates of $α$ are correlated systematically with the galaxy velocity dispersion, $σ$, and with the Mg/Fe abundance ratio. The spectroscopic method, based on the strengths of metal absorption lines, yields a correlation only with metal abundance ratios: at fixed Mg/Fe, there is no residual correlation with $σ$. The dynamical method, applied to exactly the same galaxy sample, yields the opposite result: the IMF variation correlates only with dynamics, with no residual correlation with Mg/Fe after controlling for $σ$. Hence although both methods indicate a heavy IMF on average in ellipticals, they lead to incompatible results for the systematic trends, when applied to the same set of galaxies. Although other explanations are possible, the sense of the disagreement suggests that one (or both) of the methods has not accounted fully for the main confounding factors, i.e. element abundance ratios or dark matter contributions."},"bibtype":"misc","biburl":"http://www.bibsonomy.org/bib/author/Smith?items=1000","downloads":0,"keywords":["early-type galaxy imf variation"],"search_terms":["variations","initial","mass","function","early","type","galaxies","critical","comparison","between","dynamical","spectroscopic","results","smith"],"title":"Variations in the initial mass function in early-type galaxies: A critical comparison between dynamical and spectroscopic results","year":2014,"dataSources":["DvJyE8CDhC2bX8rnN"]}