Galaxy and Mass Assembly (GAMA): the star formation rate dependence of the stellar initial mass function

By M. Gunawardhana, Andrew M. Hopkins, R. Sharp, S. Brough, E. Taylor, Joss Bland-Hawthorn, C. Maraston, R. Tuffs, C. Popescu, D. Wijesinghe and 28 more. 2011

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The stellar initial mass function (IMF) describes the distribution in stellar masses produced from a burst of star formation. For more than 50 yr, the implicit assumption underpinning most areas of research involving the IMF has been that it is universal, regardless of time and environment. We measure the high-mass IMF slope for a sample of low-to-moderate redshift galaxies from the Galaxy and Mass Assembly survey. The large range in luminosities and galaxy masses of the sample permits the exploration of underlying IMF dependencies. A strong IMF–star formation rate dependency is discovered, which shows that highly star-forming galaxies form proportionally more massive stars (they have IMFs with flatter power-law slopes) than galaxies with low star formation rates. This has a significant impact on a wide variety of galaxy evolution studies, all of which rely on assumptions about the slope of the IMF. Our result is supported by, and provides an explanation for, the results of numerous recent explorations suggesting a variation of or evolution in the IMF.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/97ec3efb75fc1aa6b9080144dd4a969bb00fe41b

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Citations in the corpus

Herschel-ATLAS: rapid evolution of dust in galaxies over the last 5 billion years (2010, unknown): “Such IMFs have been postulated to explain observations of high-z sub-mm galaxies, highly star-forming galaxies in the local Universe and galaxies with high molecular gas densities (Baugh et al. 2005; Papadopoulos 2010; Gunawardhana et al. 2011).”
A unified multiwavelength model of galaxy formation (2015, background): “From a study of the spectra of nearby star-forming galaxies, Gunawardhana et al. (2011) infer an IMF that becomes more top-heavy with increasing SFR, with the IMF slope flatteningto x ≈ 0.9 (similar to our starburst IMF) in the most actively starforming galaxies in their sample.”
GALAXY AND MASS ASSEMBLY (GAMA): MID-INFRARED PROPERTIES AND EMPIRICAL RELATIONS FROM WISE (2014, methodology): “SFRs can be derived from the Hα equivalent width, combined with the r-band absolute magnitude, and are available for the GAMA phase-I survey (rAB < 19.4 in G15 and rAB < 19.8 in G12) as determined in Gunawardhana et al. (2011, 2013).”
Galaxy and mass assembly (GAMA): End of survey report and data release 2 (2015, background): “…the effect of mergers on the stellar mass function (Robotham et al. 2014), to study variations and dependences of the galaxy initial mass function (Gunawardhana et al. 2011) and of the star formation rate (SFR; Wijesinghe et al. 2012), and to investigate satellite galaxies (Prescott et al. 2011;…”
The relation between metallicity, stellar mass and star formation in galaxies: an analysis of observational and model data (2011, background): “However, there are currently conflicting conclusions in the literature as to whether such a variable IMF is present in the real Universe (e.g. Elmegreen 2006; Weidner & Kroupa 2006; Fumagalli, Da Silva & Krumholz 2011; Gunawardhana et al. 2011).”
Galaxy And Mass Assembly (GAMA): Spectroscopic analysis (2013, background): “…demonstrates that high line luminosity systems show a much broader distribution of obscuration properties than lower luminosity galaxies, consistent with earlier results (Hopkins et al. 2001, 2003; Pérez-González et al. 2003; Afonso et al. 2003; López-Sánchez 2010; Gunawardhana et al. 2011).”
HERSCHEL-ATLAS GALAXY COUNTS AND HIGH-REDSHIFT LUMINOSITY FUNCTIONS: THE FORMATION OF MASSIVE EARLY-TYPE GALAXIES (2011, methodology): “Indeed, recent observational evidences (Gunawardhana et al. 2011; Dunne et al. 2011) indicate that highly star forming galaxies have IMFs dN/dm ∝ m−x with flatter high-mass power-law slopes x than galaxies with low star formation rates.”
A CATALOG OF BULGE, DISK, AND TOTAL STELLAR MASS ESTIMATES FOR THE SLOAN DIGITAL SKY SURVEY (2013, background): “…IMF locally (Kroupa 2001), over the past several years there has been mounting evidence for systematic variation of the stellar IMF as a function of galaxy properties (e.g., Cenarro et al. 2003; Hoversten & Glazebrook 2008; van Dokkum & Conroy 2010; Gunawardhana et al. 2011; Dutton et al. 2012).”
The big problems in star formation: The star formation rate, stellar clustering, and the initial mass function (2014, background): “…rates show systematic deficiencies in the amount of Hα they produce per unit far ultraviolet (FUV) emission (Boissier et al. 2007; Lee et al. 2009; Boselli et al. 2009; Meurer et al. 2009), and systematically low Hα equivalent widths (Hoversten & Glazebrook 2008; Gunawardhana et al. 2011).”
The ATLAS3D project – XX. Mass–size and mass–σ distributions of early-type galaxies: bulge fraction drives kinematics, mass-to-light ratio, molecular gas fraction and stellar initial mass function (2012, result): “Using this technique, Hoversten & Glazebrook (2008) inferred a variation of the IMF with more massive galaxies having a more top-heavy IMF than Salpeter, a result confirmed under the same assumptions (Gunawardhana et al. 2011) by the Galaxy and Mass Assembly (GAMA) survey (Driver et al. 2011).”
THE ARECIBO LEGACY FAST ALFA SURVEY: THE GALAXY POPULATION DETECTED BY ALFALFA (2012, background): “Other factors causing scatter include different SFHs, metallicities, as well as different population synthesis models and even IMFs (Gunawardhana et al. 2011).”