High‐resolution morphology and surface photometry of KIG 685 and KIG 895 with ARGOS+LUCI using the Large Binocular Telescope

Abstract

We aim to refine the sample of isolated early‐type galaxies in the Analysis of the interstellar Medium of Isolated Galaxies (AMIGA) catalog via high‐resolution imaging. Here, we report the result from a pilot study investigating two candidates, KIG 685 and KIG 895, in K‐band with the laser guide star and wavefront sensing facility ARGOS using the Large Binocular Telescope (LBT). Observations, obtained during the commissioning time, achieved a point spread function (PSF) of ≈0.25″. We present the data reduction and the PSF analysis from the best closed‐loop exposures to investigate the galaxies' morphological structure, including their nuclear region. We used PROFILER for the decomposition of the azimuthal 1D light distribution and GALFIT for the 2D analysis, accounting for ARGOS's PSF. KIG 685 was found to be a S0 galaxy and has been modeled with two Sérsic components representing a pseudobulge (n1D = 2.87 ± 0.21, n2D = 2.29 ± 0.10) and a disk (n1D = 0.95 ± 0.16, n2D = 0.78 ± 0.10). Nearly symmetric ring‐/shell‐like structures emerge after subtracting the GALFIT model from the image. KIG 895 shows a clear irregular arm‐like structure, in which the northern outer arm is reminiscent of a tail. The galaxy body is a disk, best fitted by a single Sérsic profile (n1D = 1.22 ± 0.1; n2D = 1.32 ± 0.12), that is, KIG 895 is a bulge‐less, very late‐type spiral. ARGOS high‐resolution images clearly showed interaction signatures in KIG 895. We suggest that the ring‐/shell‐like residuals in KIG 685, a bona fide early‐type galaxy, point toward a past accretion event.

Morphology and surface photometry of a sample of isolated early-type galaxies from deep imaging

“…However, the plot shows no significant geometric distortions where the galaxy is located. One direct comparison can be made using KIG 685, which was observed by Rampazzo et al (2019, see their Table 3) with adaptive optics at the LBT. The ellipticity measured by these authors in K band is 0.16 ± 0.05, which is well comparable within the errors with the values of 0.18 ± 0.05 for the bulge that dominates the light profile (B/T = 0.74) in both bands.…”

“…In this subsection we discuss the results summarised by the figures in Appendix A. Detailed surface photometric studies have been dedicated to some of the iETGs we study here by H-T, Rampazzo et al (2019) in the K band and by Costantin et al (2018) in the SDSS i band. Automatic surface photometry and 2D luminosity profile decomposition in these SLOAN bands have also been performed for some objects by Simard et al (2011) and by Meert et al (2015).…”

“…H-T considered the galaxy an S0, however. Rampazzo et al (2019) fit the high-resolution (PSF = 0 . 25) K-band 2D light distribution best with GALFIT, adopting a model composed of two Sérsic laws representing a pseudo-bulge (n = 2.95 ± 0.10) plus a disc (n = 0.78 ± 0.10).…”

“…The authors report a 50% incidence of ripples and shells in these Es (9 out of 18), see Table 6 of the paper, although 4 are uncertain detections) as well as a high fraction of Es with diffuse halo (7 out of 18). Recently, Rampazzo et al (2019) found interaction and merging signatures in a high spatial resolution study in K band, performed with ARGOS+LUCI at the Large Binocular Telescope (LBT; Rabien et al 2019), of KIG 685 and KIG 895. This latter has been found to be a misclassified spiral with a tail.…”