Searching for Extragalactic Sources in the VISTA Variables in the Vía Láctea Survey

Baravalle, L. D.; Alonso, M. V.; Castellón, José Luis Nilo; Beamín, Juan Carlos; Minniti, D.

doi:10.3847/1538-3881/aa9ee2

Cited by 21 publications

(37 citation statements)

References 37 publications

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“…Another interesting feature of these CMDs is the branch of very dim and red sources that appears at magnitudes fainter than K s > 16 and colors J−K s > 1.3 (Z−K s > 2.3). These sources can be associated with background galaxies, as some studies suggest (Lucas et al 2008;Coldwell et al 2014;Baravalle et al 2018), although at the faintest magnitudes this sequence is expected to be heavily contaminated with the tail of Galactic stars with higher photometric errors. We note that this sequence is more noticeable in the K s vs J − K s CMD, while the previously mentioned BHB sequence manifests more clearly in the K s vs Z − K s CMD.…”

Section: Cmds Of the Galactic Bulge Fields In The Vvvmentioning

confidence: 99%

Milky Way demographics with the VVV survey

Alonso-García

Saito

Hempel

et al. 2018

A&A

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Context. The inner regions of the Galaxy are severely affected by extinction, which limits our capability to study the stellar populations present there. The Vista Variables in the Vía Láctea (VVV) ESO Public Survey has observed this zone at near-infrared wavelengths where reddening is highly diminished. Aims. By exploiting the high resolution and wide field-of-view of the VVV images we aim to produce a deep, homogeneous, and highly complete database of sources that cover the innermost regions of our Galaxy. Methods. To better deal with the high crowding in the surveyed areas, we have used point spread function (PSF)-fitting techniques to obtain a new photometry of the VVV images, in the ZY JHKs near-infrared filters available. Results. Our final catalogs contain close to one billion sources, with precise photometry in up to five near-infrared filters, and they are already being used to provide an unprecedented view of the inner Galactic stellar populations. We make these catalogs publicly available to the community. Our catalogs allow us to build the VVV giga-CMD, a series of color-magnitude diagrams of the inner regions of the Milky Way presented as supplementary videos. We provide a qualitative analysis of some representative CMDs of the inner regions of the Galaxy, and briefly mention some of the studies we have developed with this new dataset so far.

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Section: Cmds Of the Galactic Bulge Fields In The Vvvmentioning

confidence: 99%

Milky Way demographics with the VVV survey

Alonso-García

Saito

Hempel

et al. 2018

A&A

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“…In this way, we generated a multi-band catalogue with all detected sources. SExtractor recognised and separated from the background noise all the objects with a threshold more than twice the medium brightness of the sky and spanned over at least ten connected pixels on the VVV images (Coldwell et al 2014;Baravalle et al 2018). A filter convolution was applied over the images by SExtractor with the aim being to efficiently separate low-surface-brightness objects from spurious detections.…”

Section: Automatic Detectionmentioning

confidence: 99%

“…Nevertheless, the improved extinction correction changes the mean colour to 0.988 with a standard deviation of ±0.12, which is in good agreement with the high-latitude sample. Baravalle et al (2018) also define similar colour cuts to separate star from galaxy candidates. In addition, Amôres et al (2012) and Coldwell et al (2014) found that objects selected as galaxy candidates from the VVV survey show mainly J-Ks> 1.0 colours.…”

Section: Automatic Catalogue Of Extended Sourcesmentioning

confidence: 99%

“…Following Amôres et al (2012), Coldwell et al (2014) and Baravalle et al (2018), we carried out a visual inspection in order to verify the automatic detection made with SExtractor. We performed a visual identification of galaxy candidates using Aladin (Bonnarel et al 2000).…”

Section: Visual Catalogue Of Galaxy Candidatesmentioning

confidence: 99%

“…Furthermore, Coldwell et al (2014) found the VVV NIR galaxy counterparts of a new cluster of galaxies at redshift z = 0.13 detected in X-ray by SUZAKU (Mori et al 2013). In addition, Baravalle et al (2018) found 530 new galaxy candidates in two different tiles in the region of the Galactic disk. These latter authors detected and characterised the candidates using a combination of SExtractor and PSFEx techniques.…”

Section: Introductionmentioning

confidence: 99%

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Overdensity of VVV galaxies behind the Galactic bulge

Galdeano

Pereyra

Duplancic

et al. 2021

A&A

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Context. The extragalactic vision we have through the Milky Way is very unclear. There is significant extinction of the optical emission from objects located in the region called the zone of avoidance (ZOA). NIR wavelengths are less affected by extinction, and therefore the infrared surveys in this zone are a potential source of astronomical discoveries. Nevertheless, these observations need to be compared with cosmological simulations in order to carry out high−accuracy studies. Aims. Our aim is to identify extragalactic sources in the ZOA, using infrared images of the VVV survey. We consider mock galaxy catalogues in order to interpret observational results. Methods. We studied a region of 1.636 square degrees corresponding to the VVV tile b204. Using SExtractor, we analysed photometric data generating a catalogue of extended sources in this area. In order to confirm these sources as galaxy candidates we visually inspected RGB images looking for typical galaxy features. Using 2MASX and GCMW catalogued sources we tested completeness and contamination of our catalogue and define suitable colour cuts to select galaxies. We also compared the observational results with those obtained from two semi-analytical models on Dark Matter simulations. One galaxy catalogue was constructed with the SAG semi-analytic model of galaxy formation, and the other one was constructed with the L-Galaxies semi-analytic model. Results. By adopting CLASS_STAR < 0.5, r1/2 > 0.7 arcsec and specific colour cuts (J − Ks > 0.97, J − H > 0 and H − Ks > 0) we generated an automatic catalogue of extended sources. After visual inspection we identified 624 sources with 10 < Ks < 17 as galaxy candidates. The contamination of the automatic catalogue is 28% when considering visually confirmed galaxies as reliable objects. The estimated completeness is 87% up to magnitude Ks = 13.5. We analysed the spatial distribution of galaxy candidates, finding a high concentration of galaxies in a small region of 15 arcmin radius. This region has three times higher density than similar areas in the tile. We compared the number of galaxies in this small area with the mean density values obtained from a suitable sample of galaxies from semi-analytic models finding that our results are consistent with an overdensity region. Conclusions. Using VVV near-infrared data and mock catalogues we detect new extragalactic sources that have not been identified by other catalogues. We demonstrate the potentiality of the VVV survey in finding and studying a large number of galaxy candidates and extragalactic structures obscured by the Milky Way.

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The globular cluster system of the nearest Seyfert II galaxy Circinus

Obasi

Gómez

Minniti

et al. 2023

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Context. The globular cluster (GC) system of Circinus galaxy has not been probed previously partly because of the location of the galaxy at −3.8° Galactic latitude, which suffers severely from interstellar extinction, stellar crowding, and Galactic foreground contamination. However, the deep near-infrared (NIR) photometry by the VISTA Variables in the Via Láctea Extended Survey (VVVX) in combination with the precise astrometry of Gaia EDR3 allow us to map GCs in this region. Aims. Our long-term goal is to study and characterise the distributions of GCs and ultra-compact dwarfs in Circinus galaxy, which is the nearest Seyfert II galaxy. Here we conduct the first pilot search for GCs in this galaxy. Methods. We used NIR VVVX photometry in combination with Gaia EDR3 astrometric features, such as astrometric excess noise and the ratio of the sum of the blue photometer (BP) and red photometer (RP) to the broad G passband (BRexcess), to build the first homogeneous catalogue of GCs in Circinus galaxy. A robust combination of selection criteria allows us to effectively clean interlopers from our sample. Results We report the detection of ∼70 GC candidates in this galaxy at a 3σ confidence level. They show a bimodal colour distribution with the blue peak at (G − Ks)0 = 0.985±0.127 mag with a dispersion of 0.211±0.091 mag and the red peak at (G − Ks)0 = 1.625±0.177 mag with a dispersion of 0.482±0.114 mag. A GC specific frequency (SN) of 1.3±0.2 was derived for the galaxy, and we estimated a total population of 120±40 GCs. Based on the projected radial distribution it appears that Circinus has a different distribution of GC candidates than MW and M 31. Conclusions. We demonstrate that Circinus galaxy hosts a sizeable number of cluster candidates. This result is the first leap towards understanding the evolution of old stellar clusters in this galaxy.

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Searching for Extragalactic Sources in the VISTA Variables in the Vía Láctea Survey

Cited by 21 publications

References 37 publications

Milky Way demographics with the VVV survey

Milky Way demographics with the VVV survey

Overdensity of VVV galaxies behind the Galactic bulge

The globular cluster system of the nearest Seyfert II galaxy Circinus

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