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We present the near-infrared observations of population II Cepheids in theGalactic bulge from VVV survey. We identify 340 population II Cepheids in theGalactic bulge from VVV survey based on their match with OGLE-III Catalogue.The single-epoch $JH$ and multi-epoch $K_s$ observations complement theaccurate periods and optical $(VI)$ mean-magnitudes from OGLE. The sampleconsisting of BL Herculis and W Virginis subtypes is used to deriveperiod-luminosity relations after correcting mean-magnitudes for theextinction. Our $K_s$-band period-luminosity relation, $K_s =-2.189(0.056)~[\log(P) - 1] + 11.187(0.032)$, is consistent with published workfor BL Herculis and W Virginis variables in the Large Magellanic Cloud. Wepresent a combined OGLE-III and VVV catalogue with periods, classification,mean magnitudes and extinction for 264 Galactic bulge population II Cepheidshaving good-quality $K_s$-band light curves. The absolute magnitudes forpopulation II Cepheids and RR Lyraes calibrated using Gaia and Hubble SpaceTelescope parallaxes, together with calibrated magnitudes for Large MagellanicCloud population II Cepheids, are used to obtain a distance to the Galacticcenter, $R_0=8.34\pm0.03{\mathrm{(stat.)}}\pm0.41{\mathrm{(syst.)}}$, whichchanges by $^{+ 0.05}_{-0.25}$ with different extinction laws. While noting thelimitation of small number statistics, we find that the present sample ofpopulation II Cepheids in the Galactic bulge shows a nearly spheroidal spatialdistribution, similar to metal-poor RR Lyrae variables. We do not find evidenceof the inclined bar as traced by the metal-rich red-clump stars. The numberdensity for population II Cepheids is more limited as compared to abundant RRLyraes but they are bright and exhibit a wide range in period that provides arobust period-luminosity relation for an accurate estimate of the distance tothe Galactic center.

Galactic Bulge Population II Cepheids in the VVV Survey: Period-Luminosity Relations and a Distance to the Galactic Center