Milky Way demographics with the VVV survey

Abstract

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.

Candidate Hypervelocity Red Clump Stars in the Galactic Bulge Found Using the VVV and Gaia Surveys*

“…The mean magnitude in K S must be K S < 16, in order to keep heavily reddened candidates, and maintaining a constant magnitude between the two epochs in J and as well in K S (mean magnitude-magnitude in a given epoch < 3σ). Differently from Alonso-García et al (2018), now we also required that the sources had a spatial separation between both observation epochs of 0.34 ′′ < tolerance < 2.5 ′′ , since the HVS candidates should show a larger separation between the observations. We then match the stellar position of the Gaia DR2 and the second epoch of observation (2015) from the VVV sources with a tolerance of 0.5 arcsec, resulting in a total of N = 2, 752 sources that, as before, have accurate positions in the Galactic bulge region (−10 • < l < 10 • , −10 • < b < 5 • ), optical and near-IR photometry and PMs.…”

VVV WIN 1733−3349: a low extinction window to probe the far side of the Milky Way bulge

“…Gonzalez et al (2018) made use of VVV red clump stars detected inAlonso-García et al (2018) catalogues to create a high-resolution reddening map of the inner region of the Milky Way bulge (−10 < l < 10 deg and −1.5 < b < 1.5 deg). They discovered the presence of a low extinction window right in the Galactic plane (b ∼ −0.3 deg), at just about five degrees from the Galactic centre (l ∼ −5.2 deg).…”

VVV-WIT-01: highly obscured classical nova or protostellar collision?

“…The VVV photometry presented here are profile fitting photometry, performed with an updated version of DoPhot (Schechter et al 1993;Alonso-García et al 2012) for all data in the original VVV fields (Smith et al, in prep). The absolute calibration is based on the VVV photometric catalogue of Alonso-García et al (2018) which is in turn derived from the CASU v1.3 VISTA pipeline. The VVV Survey produces near-IR multi-colour photometry in five passbands: Z (0.88 µm), Y (1.02 µm), J (1.25 µm), H (1.65 µm), and K s (2.15 µm), as well as multi-epoch photometry in K s .…”