FAST Reveals the Extended HI Halo and Accretion Signatures of NGC2683

TL;DR

This study uses FAST radio telescope observations to reveal an extensive HI halo and signs of gas accretion in NGC2683, including detection of dwarf galaxies and high-velocity clouds, indicating ongoing galaxy growth.

Contribution

First detailed HI halo detection of NGC2683 with FAST, showing extended gas distribution and evidence of external gas accretion not observed with previous VLA data.

Findings

FAST detects HI extending four times farther than VLA

Identifies three dwarf galaxies near NGC2683, suggesting accretion

Detects high-velocity clouds indicating ongoing gas accretion

Abstract

We present the results of our recent HI observations conducted on the edge-on galaxy NGC2683 using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). In comparison to previous observations made by the VLA, FAST has detected a more extensive distribution of HI. Particularly noteworthy is that the detections made by FAST extend approximately four times farther than those of the VLA in the vertical direction from the galactic plane. The total HI flux measured for NGC2683 amounts to $F_{\rm HI} = 112.1\,\rm{Jy\,km\,s^{-1}}$ (equivalent to a total HI mass of $M_{\rm HI} = 2.32 \times 10^9\,{\rm M_\odot}$), which is slightly higher than that detected by VLA. FAST has also identified three dwarf galaxies in close proximity to NGC2683, namely KK69, NGC2683dw1 (hereafter dw1), and NGC2683dw3$?$ (hereafter dw3$?$). dw3$?$ is situated within the extended HI distribution of NGC2683 in projection and lies near the tail of KK69 extending towards NGC2683. These observations suggest that dw3$?$ is likely a result of the accretion process from NGC2683 to KK69. Furthermore, FAST has detected three high-velocity clouds (HVCs), with complex B potentially undergoing accretion with NGC2683. Based on the model from Vollmer et al. 2016 and incorporating the HI halo component, we found that the model with the added HI halo aligns more closely with our FAST observations in NGC2683. The estimated mass of this HI halo is $3 \times 10^8\,{\rm M_\odot}$, constituting approximately 13% of the total HI mass of the galaxy. We suggest that the origination of this HI halo is more likely attributed to external gas accretion.