Stellar sources of dust in the high-redshift Universe

Abstract

With the aim of investigating whether stellar sources can account for the ≥10 8 M dust masses inferred from mm/sub-mm observations of samples of 5 < z < 6.4 quasars, we develop a chemical evolution model which follows the evolution of metals and dust on the stellar characteristic lifetimes, taking into account dust destruction mechanisms. Using a grid of stellar dust yields as a function of the initial mass and metallicity over the range 1-40 M and 0-1 Z , we show that the role of asymptotic giant branch (AGB) stars in cosmic dust evolution at high redshift might have been overlooked. In particular, we find that (i) for a stellar population forming according to a present-day Larson initial mass function (IMF) with m ch = 0.35 M , the characteristic time-scale at which AGB stars dominate dust production ranges between 150 and 500 Myr, depending both on the assumed star formation history and on the initial stellar metallicity; (ii) this result is only moderately dependent on the adopted stellar lifetimes, but it is significantly affected by variations of the IMF: for a m ch = 5 M , dust from AGB starts to dominate only on time-scales larger than 1 Gyr and SNe are found to dominate dust evolution when m ch ≥10 M . We apply the chemical evolution model with dust to the host galaxy of the most distant quasar at z = 6.4, SDSS J1148+5251. Given the current uncertainties on the star formation history of the host galaxy, we have considered two models: (i) the star formation history obtained in a numerical simulation by Li et al. which predicts that a large stellar bulge is already formed at z = 6.4, and (ii) a constant star formation rate of 1000 M yr −1 , as suggested by the observations if most of the far-infrared luminosity is due to young stars. The total mass of dust predicted at z = 6.4 by the first model is 2 × 10 8 M , within the range of values inferred by observations, with a substantial contribution (∼80 per cent) of AGB dust. When a constant star formation rate is adopted, the contribution of AGB dust decreases to ∼50 per cent but the total mass of dust formed is a factor of 2 smaller. Both models predict a rapid enrichment of the interstellar medium with metals and a relatively mild evolution of the carbon abundance, in agreement with observational constraints. This supports the idea that stellar sources can account for the dust observed but show that the contribution of AGB stars to dust production cannot be neglected, even at the most extreme redshifts currently accessible to observations.

The cosmic dust rate across the Universe

“…Type II SNe and AGB stars (Valiante et al 2009;Laporte et al 2017) have been regarded as possible dust sources, however, nonstellar sources seem to be required (e. g., Mattsson 2011;Kuo & Hirashita 2012), as the contribution from stellar populations can hardly account for the amount of dust observed in some high redshift systems (e.g., Pipino et al 2011;Calura et al 2014). Such a "dust-budget crisis" can be solved by assuming a top-heavy IMF (Rowlands et al 2014) or alternative channels for dust production.…”

“…The fast dust production by Type II SNe may represent the primary channel of dust source, but also AGB or super-AGB stars have a non-negligible role (Valiante et al 2009). The role of dust accretion is also uncertain: this process seems fundamental to match observations (Mancini et al 2016;Ginolfi et al 2017), but on the other side, it encounters several problems such as a too high temperature or repulsive Coulomb barriers that may reduce or stop grain growth (Ferrara et al 2016).…”

The dust content of galaxies from z = 0 to z = 9

“…Far-infrared (FIR) and submillimeter observations have shown that even at the highest redshifts (z > 4) galaxies can have significant reservoirs of dust (10 7 M or even greater, Bertoldi et al 2003;Hughes, Dunlop & Rawlings 1997;Valiante et al 2009;Venemans et al 2012;Casey, Narayanan & Cooray 2014;Riechers et al 2014). Watson et al (2015) found a galaxy at z = 7.5 ± 0.2 with a dust mass of 4 × 10 7 M and a DTG ratio that is half of the Milky Way value.…”

Should we believe the results of ultraviolet–millimetre galaxy spectral energy distribution modelling?

“…the differences in the timescales for the various dust-production channels (e.g. Valiante et al 2009;Michałowski et al 2010b). Indeed, there is some observational evidence that dust in high-redshift galaxies differs from that in the Milky Way (e.g.…”