Constraints on a Universal IMF from UV to Near-IR Galaxy Luminosity Densities

By I. Baldry, Karl Glazebrook. 2003

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We obtain constraints on the slope of a universal stellar initial mass function (IMF) over a range of cosmic star-formation histories (SFH) using z=0.1 luminosity densities in the range from 0.2 to 2.2 microns. The age-IMF degeneracy of integrated spectra of stellar populations can be broken for the Universe as a whole by using direct measurements of (relative) cosmic SFH from high-redshift observations. These have only marginal dependence on uncertainties in the IMF, whereas, fitting to local luminosity densities depends strongly on both cosmic SFH and the IMF. We fit to these measurements using population synthesis and find the best-fit IMF power-law slope to be Gamma=1.15+-0.2 (0.5 < M/M_solar < 120). This slope is in good agreement with the Salpeter IMF slope (Gamma=1.35). A strong upper limit of Gamma<1.7 is obtained which effectively rules out the Scalo IMF due to its too low fraction of high-mass stars. This upper limit is at the 99.7% confidence level if we assume a closed-box chemical evolution scenario and 95% if we assume constant solar metallicity. Fitting to the H-alpha line luminosity density, we obtain a best-fit IMF slope in good agreement with that derived from broadband measurements. Marginalizing over cosmic SFH and IMF slope, we obtain (95% conf. ranges, h=1): omega_stars = 1.1-2.0 E-3 for the stellar mass density; rho_sfr = 0.7-4.1 E-2 M_solar/yr/Mpc^3 for the star-formation rate density, and; rho_L = 1.2-1.7 E+35 W/Mpc^3 for the bolometric, attenuated, stellar, luminosity density (0.09-5 microns). Comparing this total stellar emission with an estimate of the total dust emission implies a relatively modest average attenuation in the UV (<=1 magnitude at 0.2 microns).

Subfields: Astronomy and Astrophysics

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Citations in the corpus

The Stellar Mass Assembly of Galaxies from z = 0 to z = 4: Analysis of a Sample Selected in the Rest-Frame Near-Infrared with Spitzer (2007, methodology): “For example, a Kroupa et al. (1993) IMF (as the one used in Borch et al. 2006) predicts stellar masses smaller than ours by a factor of ∼1.7, or a Baldry & Glazebrook (2003) IMF (used in, for example, Glazebrook et al. 2004) predicts also smaller masses by a factor of ∼1.8.”
Galaxy bimodality versus stellar mass and environment (2006, methodology): “Note with the IMF and mass-to-light ratios used in this paper, Ωstars ≈ 0.002 (cf. Persic & Salucci 1992; Baldry & Glazebrook 2003; Nagamine et al. 2006). c© 2006 RAS, MNRAS 000, 1–19 Figure A1.”
The Millennium Galaxy Catalogue: the B-band attenuation of bulge and disc light and the implied cosmic dust and stellar mass densities (2007, background): “This value for the stellar baryon fraction is marginally (2σ ) higher than that previously derived by Baldry & Glazebrook (2003) of (5–9) h per cent (marginalized over a variety of IMFs).”
Star formation and mass assembly in high-redshift galaxies (2009, methodology): “Masses and SFRs of Juneau et al. (2005) were instead renormalized from a Baldry & Glazebrook (2003) to a Salpeter (1955) IMF using the factors 1.82 (Juneau et al. 2005) and 2 (Hopkins & Beacom 2006).”
On the Normalization of the Cosmic Star Formation History (2006, methodology): “The Kroupa (2001) IMF (high mass power law slope of−1.3) and the modified Salpeter B IMF (hereafter SalB IMF, Baldry & Glazebrook 2003, high mass power law slope of−1.35) have scale factors intermediate between these choices.”
Galaxy luminosities, stellar masses, sizes, velocity dispersions as a function of morphological type (2009, methodology): “We convert from their IMF (from Baldry & Glazebrook 2003) to the Chabrier IMF by multiplying by 1.135 (i.e. 0.055 dex, see Table 2).”
The galaxy stellar mass-star formation rate relation: evidence for an evolving stellar initial mass function? (2007, background): “…the most careful work on trying to reconcile fossil light measures with redshift-integrated measures of stellar mass. Extending the analyses of Baldry & Glazebrook (2003) and Hopkins & Beacom (2006) by including extragalactic background light (EBL) constraints, they found that no standard IMF…”
Evolution of the Intergalactic Opacity: Implications for the Ionizing Background, Cosmic Star Formation, and Quasar Activity (2008, methodology): “To the luminosity density measurements, dust corrections (where necessary), SFR calibrations, and IMF assumptions are applied to derive the star formation history.”
The dependence of Type Ia Supernovae luminosities on their host galaxies (2010, result): “Our results are not sensitive to this choice – we have repeated our analysis in full with both the more standard Salpeter (1955) IMF, and with a Baldry & Glazebrook (2003) IMF, and find similar results, though the Mstellar and SFRs derived for the host galaxies have (expected) small mean offsets…”
Galaxy and Mass Assembly (GAMA): the star formation rate dependence of the stellar initial mass function (2011, background): “The IMF is often parametrized as one or more power laws, describing the number of stars within a given mass interval, dNdM ∝ mα with α defining the slope for the mass range of interest (Salpeter 1955; Baldry & Glazebrook 2003).”
Quantifying the Bimodal Color-Magnitude Distribution of Galaxies (2003, result): “These IMFs were found to be consistent with cosmic SFH and luminosity densities (Baldry & Glazebrook 2003), i.e. with average galaxy colors, and with galaxy rotation curves (Bell & de Jong 2001). three different effects, a change in dominance from one distribution to the other, a change in the…”
On the galaxy stellar mass function, the mass-metallicity relation, and the implied baryonic mass function (2008, methodology): “Baldry & Glazebrook (2003) give a range from 0.035 to 0.063 from fitting to the local cosmic luminosity densities (over a range of IMFs but similar to those used here in terms of M/L) and Nagamine et al. (2006) found 0.051 ± 0.009 from fitting to various data including the extragalactic background…”
The rising star formation histories of distant galaxies and implications for gas accretion with time (2010, result): “This is similar to the findings of Baldry & Glazebrook (2003) based on SFHs derived from the UV to IR luminosity densities of low-redshift galaxies.”
Ultraviolet to Mid-Infrared Observations of Star-forming Galaxies at z ~ 2: Stellar Masses and Stellar Populations (2005, methodology): “…IMF to facilitate comparison with other work (e.g., Cole et al. 2001; Shapley et al. 2001); use of the Chabrier (2003) IMF, the IMF proposed by Baldry & Glazebrook (2003), or the “diet” Salpeter IMF used by Bell et al. (2003), would reduce the inferred stellar masses by a factor of ∼ 1.5− 1.8.”
Evidence for Solar Metallicities in Massive Star-forming Galaxies at z ≳ 2 (2004, methodology): “The GDDS masses and mass densities were calculated assuming an IMF that turns over below 0:5 M (Baldry & Glazebrook 2003; Kroupa 2001); it is therefore necessary to multiply the GDDS numbers by a factor of 1.82 for a meaningful comparison with the results presented here, derived using a Salpeter…”
Evidence for a Nonuniversal Stellar Initial Mass Function from the Integrated Properties of SDSS Galaxies (2007, background): “For example, the Miller & Scalo (1979) and Scalo (1986) solar neighborhood IMFs are rejected by integrated light approaches, i.e., Kennicutt (1983, hereafter K83), Kennicutt et al. (1994, hereafter KTC94), and Baldry & Glazebrook (2003).”