مجرة حلزونية ضلعية عند z=5.102: حدود جديدة للكون المبكر ✛ ✦

الملخص الأصلي

كما كتبه المؤلفون، بالإنجليزية arXiv:2606.25022

We report M1149-BSG-z5, a barred spiral galaxy at $$z = 5.102$$, identified in the parallel field of MACS J1149+2223 with JWST and HST. M1149-BSG-z5 is the highest redshift barred galaxy candidate to date. Both isophote ellipse fitting and structural modeling support a stellar bar of length $$a_\mathrm{bar} \approx 4.5$$ kpc, and extended spiral arms peaking at $$r \approx 5.5$$ kpc. M1149-BSG-z5 is a massive main sequence star-forming galaxy, with a stellar mass of $$10^{10.45}\rm M_\odot$$ and a star-formation rate of $$144\,\rm M_\odot/yr$$. A concentrated bulge is embedded in an extended disk with a global S\'ersic index $$n = 2.37$$. With an effective radius of $$R_{e} = 2.61\rm \ kpc$$, M1149-BSG-z5 is larger than typical galaxies at $$z \sim 5$$ and comparable to barred galaxies at $$2 < z < 4$$. M1149-BSG-z5 also hosts a broad-line AGN, with a relatively low black-hole-to-stellar mass ratio of $$\rm M_{\rm BH}/M_\ast\sim10^{-3}$$. Its metal-enriched emission-line properties indicate that it is already chemically evolved. These properties imply M1149-BSG-z5 as an early-assembled and structurally evolved galaxy. We also find that M1149-BSG-z5 resides in an overdense region with a nearby companion galaxy, suggesting an interaction-driven bar formation mechanism. Its concentrated light, early assembly and main-sequence star formation also suggest baryon-dominated, gas-rich conditions, where gravitational instability can further accelerate the bar formation.