Unveiling a new extragalactic structure hidden by the Milky Way

Galdeano, D.; Ferrero, G.; Coldwell, Georgina; Duplancic, Fernanda; Alonso, Santiago; Riffel, Rogério; Minniti, D.

doi:10.1051/0004-6361/202245034

Cited by 4 publications

(1 citation statement)

References 56 publications

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“…Using this procedure, Baravalle et al (2021) generated the VVV near-IR galaxy catalogue (VVV NIRGC) that covers the regions of the Sourthern Galactic disc. Also, Coldwell et al (2014); Baravalle et al (2019) and Galdeano et al (2021Galdeano et al ( , 2022Galdeano et al ( , 2023 used similar procedure to study the near-infrared properties of galaxies in galaxy clusters. These works were particularly focused on the galaxy detections.…”

Section: Introductionmentioning

confidence: 99%

AGN candidates in the VVV near-IR galaxy catalogue

Baravalle¹,

Schmidt²,

Alonso³

et al. 2023

Preprint

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The goal of this work is to search for Active Galactic Nuclei (AGN) in the Galactic disc at very low latitudes with |b| < 2 • . For this, we studied the five sources from the VVV near-infrared galaxy catalogue that have also WISE counterparts and present variability in the VIrac VAriable Classification Ensemble (VIVACE) catalogue. In the near-infrared colour-colour diagrams, these objects have in general redder colours compared to the rest of the sources in the field. In the mid-infrared ones, they are located in the AGN region, however there is a source that presents the highest interstellar extinction and different mid-IR colours to be a young stellar object (YSO). We also studied the source variability using two different statistical methods. The fractional variability amplitude 𝜎 𝑟 𝑚𝑠 ranges from 12.6 to 33.8, being in concordance with previous results found for type-1 AGNs. The slopes of the light curves are in the range (2.6−4.7) ×10 −4 mag/day, also in agreement with results reported on quasars variability. The combination of all these results suggest that four galaxies are type-1 AGN candidates whereas the fifth source likely a YSO candidate.

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Section: Introductionmentioning

confidence: 99%

AGN candidates in the VVV near-IR galaxy catalogue

Baravalle¹,

Schmidt²,

Alonso³

et al. 2023

Preprint

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Enlightening the Universe behind the Milky Way bulge

Duplancic,

Alonso,

Coldwell

et al. 2024

A&A

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The location of the Solar System complicates the detection extragalactic sources beyond the Milky Way plane. The optical observations are hampered in the so-called zone of avoidance (ZOA), where stellar crowding and Galactic absorption are severe. Observations at longer wavelengths are needed in order to discover new background galaxies and complete the census in the ZOA. The goal of this work is to identify galaxies behind the Milky Way bulge using near-infrared (NIR) data from the VISTA Variables in Vía Láctea (VVV) survey. To this end, we made use of different VISTA Science Archive (VSA) tools in order to extract relevant information from more than 32 billion catalogued sources in the VVV bulge region. We find that initial photometric restriction on sources from the VSA vvvSource table combined with restrictions on star--galaxy separation parameters obtained from Source Extractor is a successful strategy for achieving acceptable levels of contamination (60<!PCT!>) and high completeness (75<!PCT!>) in the construction of a galaxy target sample. To remove contaminating Galactic sources from the initial target sample, our methodology also incorporates a visual inspection of false-colour RGB images, a crucial quality control carried out following a specifically defined procedure. Under this methodology, we find 14480 galaxy candidates in the VVV bulge region, making this sample the largest catalogue to date in the ZOA. Moreover, these new sources provide a fresh picture of the Universe hidden behind the curtain of stars, dust, and gas in the unexplored Milky Way bulge region. The results from this work further demonstrate the potential of the VVV/VVVX survey to find and study a large number of galaxies and extragalactic structures obscured by the Milky Way, expanding our knowledge of the Universe in this challenging and impressive region of the sky.

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The VISTA Variables in the Vía Láctea extended (VVVX) ESO public survey: Completion of the observations and legacy

Saito,

Hempel,

Alonso-García

et al. 2024

A&A

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The ESO public survey VISTA Variables in the V\'ia L\'actea (VVV) surveyed the inner Galactic bulge and the adjacent southern Galactic disk from $2009-2015$. Upon its conclusion, the complementary VVV eXtended (VVVX) survey has expanded both the temporal as well as spatial coverage of the original VVV area, widening it from $562$ to $1700$ sq. deg., as well as providing additional epochs in s $ filters from $2016-2023$. With the completion of VVVX observations during the first semester of 2023, we present here the observing strategy, a description of data quality and access, and the legacy of VVVX. VVVX took sim \,$2000$ hours, covering about 4<!PCT!> of the sky in the bulge and southern disk. VVVX covered most of the gaps left between the VVV and the VISTA Hemisphere Survey (VHS) areas and extended the VVV time baseline in the obscured regions affected by high extinction and hence hidden from optical observations. VVVX provides a deep $JHK_ s $ catalogue of $ point sources, as well as a s $ band catalogue of sim \,$10^7$ variable sources. Within the existing VVV area, we produced a $5D$ map of the surveyed region by combining positions, distances, and proper motions of well-understood distance indicators such as red clump stars, RR Lyrae, and Cepheid variables. In March 2023 we successfully finished the VVVX survey observations that started in 2016, an accomplishment for ESO Paranal Observatory upon 4200 hours of observations for VVV+VVVX. The VVV+VVVX catalogues complement those from the Gaia mission at low Galactic latitudes and provide spectroscopic targets for the forthcoming ESO high-multiplex spectrographs MOONS and 4MOST.

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Unveiling a new extragalactic structure hidden by the Milky Way

Cited by 4 publications

References 56 publications

AGN candidates in the VVV near-IR galaxy catalogue

AGN candidates in the VVV near-IR galaxy catalogue

Enlightening the Universe behind the Milky Way bulge

The VISTA Variables in the Vía Láctea extended (VVVX) ESO public survey: Completion of the observations and legacy

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