Searching For Faint Comoving Companions To The Alpha Centauri System In The Vvv Survey Infrared Images

The VVV survey has observed the southern disk of the Milky Way in the near\ninfrared, covering 240 deg$^{2}$ in the $ZYJHK_S$ filters. We search the VVV\nSurvey images in a $\\sim$19 deg$^{2}$ field around $\\alpha$ Centauri, the\nnearest stellar system to the Sun, to look for possible overlooked companions\nthat the baseline in time of VVV would be able to uncover. The photometric\ndepth of our search reaches $Y\\sim$19.3 mag, $J\\sim$19 mag, and $K_S\\sim$17\nmag. This search has yielded no new companions in $\\alpha$ Centauri system,\nsetting an upper mass limit for any unseen companion well into the brown\ndwarf/planetary mass regime. The apparent magnitude limits were turned into\neffective temperature limits, and the presence of companion objects with\neffective temperatures warmer than 325K can be ruled out using different\nstate-of-the-art atmospheric models.\n These limits were transformed into mass limits using evolutionary models,\ncompanions with masses above 11 M$_{Jup}$ were discarded, extending the\nconstraints recently provided in the literature up to projected distances of\nd<7 000 AU from $\\alpha$ Cen AB and $\\sim$1200 AU from Proxima. In the next few\nyears, the VVV extended survey (VVVX) will allow to extend the search and place\nsimilar limits on brown dwarfs/planetary companions to $\\alpha$ Cen AB for\nseparations up to 20 000AU.\n