The First Galaxy Cluster Discovered by the VISTA Variables in the Vía Láctea Survey

Abstract

We report the first confirmed detection of the galaxy cluster VVV-J144321-611754 at very low latitudes (l = 315.836${}^{\circ }$, b = -1.650${}^{\circ }$) located in the tile d015 of the VISTA Variables in the Vía Láctea (VVV) survey. We defined the region of 30$\times$ 30 $arcmi{n}^2$ centered in the brightest galaxy finding 25 galaxies. For these objects, extinction-corrected median colors of (H - K${}_s$) = 0.34 $\pm$ 0.05 mag, (J - H) = 0.57 $\pm$ 0.08 mag and (J - K${}_s$) = 0.87 $\pm$ 0.06 mag, and R${}_{1/2}$ = 1.59 $\pm$ 0.16 $arcsec$; C = 3.01 $\pm$ 0.08; and Sersic index, n = 4.63 $\pm$ 0.39 were estimated. They were visually confirmed showing characteristics of early-type galaxies in the near-IR images. An automatic clustering analysis performed in the whole tile found that the concentration of galaxies VVV-J144321-611754 is a real, compact concentration of early-type galaxies. Assuming a typical galaxy cluster with low X-ray luminosity, the photometric redshift of the brightest galaxy is $z=$ 0.196 $\pm$ 0.025. Follow-up near-IR spectroscopy with FLAMINGOS-2 at the Gemini-South telescope revealed that the two brighter cluster galaxies have typical spectra of early-type galaxies and the estimated redshift for the brightest galaxy VVV-J144321.06-611753.9 is $z=$ 0.234$\pm$0.022 and for VVV-J144319.02-611746.1 is $z=$ 0.232$\pm$0.019. Finally, these galaxies clearly follow the cluster Red Sequence in the rest-frame near-IR color--magnitude diagram with the slope similar to galaxy cluster at redshift of 0.2. These results are consistent with the presence of a bona fide galaxy cluster beyond the Milky Way disk.

Manuscript accepted for publication in The Astrophysical Journal

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Cited by in corpus (8)

• The VVV Near-IR Galaxy Catalogue beyond the Galactic disk
• The VVV near-IR galaxy catalogue in a Northern part of the Galactic disc
• Overdensity of VVV galaxies behind the Galactic bulge
• A deep near-infrared view of the Ophiuchus galaxy cluster
• Unveiling a new structure behind the Milky Way
• AGN candidates in the VVV near-IR galaxy catalogue
• Faint galaxies in the Zone of Avoidance revealed by JWST/NIRCam
• Galaxy clustering in the VVV Near-IR Galaxy Catalogue