FAST Reveals the Extended H i Halo and Accretion Signatures of NGC 2683

Abstract

We present the results of our recent H i observations conducted on the edge-on galaxy NGC 2683 using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). In comparison to previous observations made by the Very Large Array (VLA), FAST has detected a more extensive distribution of H i . Particularly noteworthy is that the detections made by FAST extend approximately 4 times farther than those of the VLA in the vertical direction from the galactic plane. The total H i flux measured for NGC 2683 amounts to F _H _i = 112.1 Jy km s ^−1 (equivalent to a total H i mass of M _H _i = 2.32 × 10 ^9 M _⊙ ), which is slightly higher than that detected by VLA. FAST has also identified three dwarf galaxies in close proximity to NGC 2683, namely KK 69, NGC 2683dw1, and NGC 2683dw3? (hereafter dw3?). dw3? is situated within the extended H i distribution of NGC 2683 in projection and lies near the tail of KK 69 extending toward NGC 2683. These observations suggest that dw3? is likely a result of the accretion process from NGC 2683 to KK 69. Furthermore, FAST has detected three high-velocity clouds, with complex B potentially undergoing accretion with NGC 2683. Based on the model from B. Vollmer et al. and incorporating the H i halo component, we found that the model with the added H i halo aligns more closely with our FAST observations in NGC 2683. The estimated mass of this H i halo is 3 × 10 ^8 M _⊙ , constituting approximately 13% of the total H i mass of the galaxy. We suggest that the origination of this H i halo is more likely attributed to external gas accretion.

Keywords

• Galaxy accretion
• Galaxy interactions
• Interstellar medium