James Webb Space Telescope Feed Post

Abell2744-QSO1: A supermassive black hole in the early universe growing in the shadows

Composite-color image cutouts of the three images of A2744-QSO1. The 2.4'' ×2.4'' cutouts of the UNCOVER JWST-NIRCam composite-color image19 (Blue: F115W+F150W,Green: F200W+F277W, Red: F2356W+F410M+F444W) show the three images of A2744-QSO1overlaid with the NIRSpec MSA slitlets of one of our MSA masks, for example (the three images were targeted with several masks and the exact position of the object in each slit may slightly shift). Abstract: Early JWST observations have uncovered a new, substantial population of red sources that might represent a previously overlooked phase of actively growing supermassive black holes (Kocevski et al. 2023, Matthee et al. 2023, Labbe et al. 2023). One of the most intriguing examples is an extremely red, point-like object that was found to be triply-imaged by the strong lensing galaxy cluster Abell 2744 (Furtak et al. 2023), allowing an unprecedented detailed look into this enigmatic population. Here we present deep spectroscopic JWST/NIRSpec observations of this object, Abell2744-QSO1. The spectroscopy confirms that the three images are of the same object, and that it is a highly reddened (AV~3) broad emission-line Active Galactic Nucleus (AGN) at a redshift of zspec=7.0451±0.0005. From the width of Hß (FWHM=2800±250kms) we derive a black hole mass of MBH=3+2-1×107M?. We infer a very high ratio of black hole to galaxy mass of at least 3% and possibly as high as 100%, an order of magnitude or more than is seen in local galaxies. The lack of strong metal lines in the spectrum together with the high bolometric luminosity (Lbol=(1.1±0.3)×1045ergs) suggest that we are seeing the black hole in a phase of rapid growth, accreting at 30% of the Eddington limit. Based on early JWST imaging studies we estimate that such heavily reddened, low-mass black holes can be ~100 times more common than UV-selected ones at this epoch. The rapid growth and high black hole to galaxy mass ratio of A2744-QSO1 suggests that it may represent the missing link between black hole seeds (Inayoshi et al. 2020; Greene et al. 2020; Volonteri 2021) and the first luminous quasars (Fan et al. 2023).