A substantial population of low-mass stars in luminous elliptical galaxies

  title={A substantial population of low-mass stars in luminous elliptical galaxies},
  author={Pieter G. van Dokkum and Charlie Conroy},
The stellar initial mass function (IMF) describes the mass distribution of stars at the time of their formation and is of fundamental importance for many areas of astrophysics. The IMF is reasonably well constrained in the disk of the Milky Way but we have very little direct information on the form of the IMF in other galaxies and at earlier cosmic epochs. Here we report observations of the Na i doublet and the Wing–Ford molecular FeH band in the spectra of elliptical galaxies. These lines are… 
Variation in the Stellar Initial Mass Function from the Chromospheric Activity of M Dwarfs in Early-type Galaxies
Mass measurements and absorption-line studies indicate that the stellar initial mass function (IMF) is bottom-heavy in the central regions of many early-type galaxies, with an excess of low-mass
The initial mass function of a massive relic galaxy
Massive relic galaxies formed the bulk of their stellar component before z � 2 and have remained unaltered since then. Therefore, they represent a unique opportunity to study in great detail the
The IMF-SFH connection in massive early-type galaxies
The stellar initial mass function (IMF) is one of the fundamental pillars in studies of stellar populations. It is the mass distribution of stars at birth, and it is traditionally assumed to be
Star-Formation Rates of Galaxies
The measured star-formation rates (SFRs) of galaxies comprise an important constraint on galaxy evolution and also on their cosmological boundary conditions. Any available tracer of the SFR depends
The galaxy-wide initial mass function of dwarf late-type to massive early-type galaxies
Observational studies are showing that the galaxy-wide stellar initial mass function are top-heavy in galaxies with high star-formation rates (SFRs). Calculating the integrated galactic stellar
Radial variations in the stellar initial mass function of early-type galaxies
The hypothesis of a universal initial mass function (IMF) -- motivated by observations in nearby stellar systems -- has been recently challenged by the discovery of a systematic variation of the IMF
Low-mass stars (M ≲ 0.4 M☉) are thought to comprise the bulk of the stellar mass of galaxies but they constitute only of order 1 percent of the bolometric luminosity of an old stellar population.
Astrophysics: Stars throw their weight in old galaxies
A survey of a mass-selected sample of 260 early galaxies reveals systematic variation in stellar initial mass function, and suggests that models assuming a constant IMF need to be revised to explain how stars seem to sense what kind of galaxy they are creating.
A number of recent studies have proposed that the stellar initial mass function (IMF) of early type galaxies varies systematically as a function of galaxy mass, with higher mass galaxies having
The stellar populations of massive galaxies in the local Universe
  • R. McDermid
  • Physics
    Proceedings of the International Astronomical Union
  • 2012
Abstract I present a brief review of the stellar population properties of massive galaxies, focusing on early-type galaxies in particular, with emphasis on recent results from the ATLAS3D Survey. I


Evidence of Cosmic Evolution of the Stellar Initial Mass Function
Theoretical arguments and indirect observational evidence suggest that the stellar IMF may evolve with time, such that it is more weighted toward high-mass stars at higher redshift. Here we test this
On the evolutionary history of stars and their fossil mass and light
The total extragalactic background radiation can be an important test of the global star formation history (SFH). Using direct observational estimates of the SFH, along with standard assumptions
Formation of Early-Type Galaxies from Cosmological Initial Conditions
We describe high-resolution smoothed particle hydrodynamics (SPH) simulations of three approximately M* field galaxies starting from ΛCDM initial conditions. The simulations are made intentionally
Can the faint submillimetre galaxies be explained in the Λ cold dark matter model
We present predictions for the abundance of submillimetre galaxies (SMGs) and Lyman-break galaxies (LBGs) in the Λ cold dark matter cosmology. A key feature of our model is the self-consistent
The Stellar Population Histories of Local Early-Type Galaxies. I. Population Parameters
This paper commences a series of investigations into the stellar populations of local elliptical galaxies as determined from their integrated spectra. The goal of the series is to determine the star
The Low-Mass Stellar Content of Galaxies: Constraints through Hybrid Population Synthesis near 1 Micron
We present high signal-to-noise observations obtained with the RC spectrograph at the CTIO 4 m telescope of six galaxies and of a variety of dwarfs and galactic bulge giants in the 9800-10200 A
On the variation of the initial mass function
A universal initial mass function (IMF) is not intuitive, but so far no convincing evidence for a variable IMF exists. The detection of systematic variations of the IMF with star-forming conditions
Infrared Spectra of Low-Mass Stars: Toward a Temperature Scale for Red Dwarfs
We present new low-resolution (R ~ 250) 1.0-2.4 pm spectra for 13 red dwarf stars. The sample size is increased to 16 by including other published infrared spectra. New, as well as published, red
Metals, dust and the cosmic microwave background: fragmentation of high-redshift star-forming clouds
We investigate the effects of the Cosmic Microwave Background (CMB) radiation field on the collapse of prestellar clouds. Using a semi-analytic model to follow the thermal evolution of clouds with
Timescales for Low-Mass Star Formation in Extragalactic Environments: Implications for the Stellar Initial Mass Function
We investigate the physical and chemical conditions necessary for low-mass star formation in extragalactic environments by calculating various characteristic timescales associated with star formation