James Webb Space Telescope Feed Post

Harvard ADS: Searching For JWST's Little Red Dots

Paper abstract: Recent observations by the James Webb Space Telescope (JWST) have revealed a previously hidden population of extremely bright and compact objects between redshifts of z ~ 4 and z ~ 10. Given their extreme red colouring in the observed frame these galaxies have been dubbed Little Red Dots (LRDs). The aim of this project was to identify LRDs using photometric data from previously uninvestigated JWST datasets and to estimate their AGN fractions by fitting the spectral energy distribution of each galaxy against well calibrated templates using CIGALE. We identified a list of potential LRDs using a single colour cut of F444W-F277W >1.5 mag and by applying a morphological analysis. We used EAZY to estimate the (photometric) redshift and CIGALE to estimate the AGN fraction of each LRD. Overall, we identified 14 LRDs, applying accurate SED fits to 11 of them. We found that 7 of them had a high AGN fraction (with the AGN component generating more than 50\% of the observed flux), a further two LRDs 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 displayed extremely high photometric redshifts (z_{phot} \gtrsim 11) and require further analysis (and may also host a supermassive black hole in their centre).