On bursty star formation during cosmological reionisation – Influence on the metal and dust content of low-mass galaxies
Year: 2026
Type: article
Abstract: Observations indicate that high-redshift galaxies undergo episodic star formation bursts, driving strong outflows that expel gas and suppress accretion. We investigate the consequences for metal and dust content of galaxies at $z\geq\!5$ using our semi-analytical model, Ashvini . We track gas-phase and stellar metallicities ( $Z_{\textrm g}, Z_{\star}$ ) and dust mass ( $M_{\textrm{d}}$ ) in dark matter haloes spanning $M_{\textrm{h}} = 10^6{-}10^{11}\,\text{M}_{\odot}$ , comparing continuous and bursty star formation scenarios – which reflect underlying assumptions of instantaneous and delayed feedback – and we allow for metallicity-dependent feedback efficiency. Delayed feedback induces oscillations in $Z_{\textrm{g}}$ and $Z_{\star}$ , with $Z_{\textrm{g}}$ declining sharply at low stellar and halo masses; the mass scale of this decline increases towards lower redshift. Reionisation introduces significant scatter in $Z_{\textrm{g}}$ , producing an upturn followed by rapid decline. Metallicity-dependent feedback moderates this decline at $z=7{-}10$ , flattening the $Z_{\textrm{g}}$ –mass relation to $\simeq$ $0.03$ – $0.04\,\text{Z}_{\odot}$ . Dust production tracks $Z_{\textrm{g}}$ but is sensitive to burst history, causing delayed enrichment. Our results show that burst-driven feedback decouples $Z_{\textrm{g}}$ and $Z_{star}$ , imprints intrinsic scatter in mass–metallicity relations, and delays dust growth. These effects are strongest in low-mass halos ( $M_{\textrm{h}}\sim 10^7\,\text{M}_{\odot}$ ), where shallow potentials amplify the impact of feedback. Our results are consistent with recent hydrodynamical and semi-analytical simulations and provide context for interpreting James Webb Space Telescope metallicity and dust measurements, highlighting the importance of episodic star formation in early galaxy chemical evolution.
Authors: Anand Menon, Sreedhar Balu, Chris Power
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,550
OpenAlex ID: W7141172147