2025/02/27 by Marshall, Madeline A., Windhorst, Rogier A., Ferrami, Giovanni +35 · 2 citations
#Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2502.20550
We present JWST NIRSpec integral field spectroscopy observations of the z=5.89 quasar NDWFS J1425+3254 from 0.6-5.3 microns, covering the rest-frame ultraviolet and optical at a spectral resolution of R~100. The quasar has a black hole mass of M_\rmBH=(1.4\substack+3.1 -1.0)×109 M_\odot and an Eddington ratio of L_\rmBol/L_\rmEdd=0.3\substack+0.6 -0.2, as implied from the broad Balmer Hα and Hβ lines. The quasar host has significant ongoing obscured star formation, as well as a quasar-driven outflow with velocity 6050\substack+460 -630 km/s and ionised outflow rate of 1650\substack+130 -1230M_\odotyr-1. This is possibly one of the most extreme outflows in the early Universe. The data also reveal that two companion galaxies are merging with the quasar host. The north-eastern companion galaxy is relatively old and very massive, with a luminosity-weighted stellar age of 65\substack+9 -4 Myr, stellar mass of (3.6\substack+0.6 -0.3)×1011 M_\odot, and star-formation rate (SFR) of ~15-30 M_\odotyr-1. A bridge of gas connects this companion galaxy and the host, confirming their ongoing interaction. A second merger is occurring between the quasar host and a much younger companion galaxy to the south, with a stellar age of 6.7±1.8 Myr, stellar mass of (1.9±0.4)×1010 M_\odot, and SFR of ~40-65 M_\odotyr-1. There is also another galaxy in the field, likely in the foreground at z=1.135, which could be gravitationally lensing the quasar with magnification 1<μ<2, and, thus, <0.75 mag. Overall, the system is a 'train-wreck' merger of three galaxies, with star formation and extreme quasar activity that were likely triggered by these ongoing interactions.