James Webb Space Telescope Feed Post

Arxiv: Searching For JWST's Little Red Dots Published: 9/20/2024 3:12:52 PM Updated: 9/20/2024 3:12:52 PM

Paper abstract: Recent observations by the James Webb Space Telescope (JWST) have revealed apreviously hidden population of extremely bright and compact objects betweenredshifts of z ~ 4 and z ~ 10. Given their extreme red colouring inthe observed frame these galaxies have been dubbed Little Red Dots (LRDs). Theaim of this project was to identify LRDs using photometric data from previouslyuninvestigated JWST datasets and to estimate their AGN fractions by fitting thespectral energy distribution of each galaxy against well calibrated templatesusing CIGALE. We identified a list of potential LRDs using a single colour cutof F444W-F277W >1.5 mag and by applying a morphological analysis. We usedEAZY to estimate the (photometric) redshift and CIGALE to estimate the AGNfraction of each LRD. Overall, we identified 14 LRDs, applying accurate SEDfits to 11 of them. We found that 7 of them had a high AGN fraction (with theAGN component generating more than 50\% of the observed flux), a further twoLRDs had AGN contribution in excess of approximately 40\%. In total nine LRDs(our of 14) are likely to have a supermassive black hole in their centre.Interestingly, the three LRDs which could not be well fit by CIGALE displayedextremely high photometric redshifts (z_{phot} \gtrsim 11) and requirefurther analysis (and may also host a supermassive black hole in their centre).