Unveiling a new structure behind the Milky Way

Abstract

Context. The ZOA does not allow clear optical observations of extragalactic sources behind the Milky Way due to the meaningful extinction of the optical emission of these objects. The observations in NIR wavelengths represent a potential source of astronomical discoveries supporting the detection of new galaxies, completing the picture of the large scale structure in this still little explored area of the sky. Aims. Our aim is to decipher the nature of the overdensity located behind the Milky Way, in the tile b204 of the VVV survey. Methods. We studied an area of six arcmin around a galaxy concentration located at l = 354.82° and b = -9.81°. We selected five galaxies taking into account the source distribution on the sky, in order to optimise the requested time for the observations, and we obtained the spectra with Flamingos 2 long-slit spectrograph at Gemini South 8.1-meter telescope. To identify and characterise the absorption features we have fitted the galaxies underlying spectrum using the starlight code together with the IRTF stellar library. In addition, the spectroscopic findings are reinforced using complementary photometric techniques such as red-sequence and photometric redshift estimation. Results. The mean spectroscopic redshift estimated from the NIR spectra is z = 0.225 +- 0.014. This value presents a good agreement with that obtained from photometric analysis, photoz = 0.21 +- 0.08, and the probability distribution function of the galaxies in the studied region. Also, the red-sequence slope is consistent with the one expected for NIR observations of galaxy clusters. Conclusions. The redshifts obtained from both, photometric and spectroscopic techniques are in good agreement allowing the confirmation of the nature of this structure at z = 0.225 +- 0.014, unveiling a new galaxy cluster, VVVGCl-B J181435-381432, behind the Milky Way bulge.

8 pages, 6 figures

References in corpus (15)

• EAZY: A Fast, Public Photometric Redshift Code
• Probing the near infrared stellar population of Seyfert galaxies
• Discovery of a supercluster in the ZOA in Vela
• The Stellar Spectral Features of Nearby Galaxies in the Near-Infrared: Tracers of Thermally-Pulsing Asymptotic Giant Branch Stars?
• The 2MASS Redshift Survey in the Zone of Avoidance
• Optical/NIR stellar absorption and emission-line indices from luminous infrared galaxies
• Gemini NIFS survey of feeding and feedback processes in nearby Active Galaxies: VI -- Stellar Populations
• Searching for Extragalactic Sources in the VISTA Variables in the Vía Láctea Survey
• The VVV Near-IR Galaxy Catalogue beyond the Galactic disk
• Confirmation of a cluster of galaxies hidden behind the Galactic bulge using the VVV Survey
• The First Galaxy Cluster Discovered by the VISTA Variables in the Vía Láctea Survey
• The FSVS Cluster Catalogue: Galaxy Clusters and Groups in the Faint Sky Variability Survey
• Overdensity of VVV galaxies behind the Galactic bulge
• A deep near-infrared view of the Ophiuchus galaxy cluster
• Mass Calibration of Galaxy Clusters at Redshift 0.1-1.0 using Weak Lensing in the Sloan Digital Sky Survey Stripe 82 Co-add

Cited by in corpus (2)

• The VISTA Variables in the Vía Láctea eXtended (VVVX) ESO public survey: Completion of the observations and legacy
• AGN candidates in the VVV near-IR galaxy catalogue