A Catalog of 971 FR I Radio Galaxies from the FIRST Survey via Hybrid Deep Learning and Ridgeline Flux Density Distribution Analysis

Abstract We present a catalog of 971 FR I radio galaxies (FR Is) identified from the Very Large Array Faint Images of the Radio Sky at Twenty centimeters (FIRST) survey. The identifications were made using a hybrid method that combines deep learning with ridgeline flux density distribution analysis. Among these sources, 845 are new discoveries. The catalog comprises sources characterized by edge-darkened double jets, an absence of significant bent morphology, and angular sizes ranging from 23″ to 159″. Optical and/or infrared counterparts have been identified for 813 FR Is. Among these, the host galaxies are predominantly (88.1%) red galaxies, with the remainder (11.9%) being blue galaxies; notably, most blue galaxies exhibit high radio power. The FR I sample spans a radio power range of 1.20 × 10 21 ≤ P 1400 ≤ 3.55 × 10 27 W Hz −1 at 1400 MHz and reaches redshifts up to z = 2.307. The host galaxies have r -band absolute magnitudes in the range of −24 ≲ M r ≲ −20 mag. For the 512 FR Is with estimates, the black hole masses fall within 10 7 ≲ M BH ≲ 7.94 × 10 9 M ⊙ . Based on optical emission-line ratios and mid-infrared colors, spectroscopic classification shows that 571 hosts are low-excitation radio galaxies and 59 are high-excitation radio galaxies.