We report observations of the Type Iax supernova ( SN Iax ) 2012Z at optical and near-infrared wavelengths from immediately after the explosion until \sim 260 days after the maximum luminosity using the Optical and Infrared Synergetic Telescopes for Education and Research ( OISTER ) Target-of-Opportunity ( ToO ) program and the Subaru telescope .
We found that the near-infrared ( NIR ) light curve evolutions and color evolutions are similar to those of SNe Iax 2005hk and 2008ha .
The NIR absolute magnitudes ( M _ { J } \sim - 18.1 mag and M _ { H } \sim - 18.3 mag ) and the rate of decline of the light curve ( \Delta m _ { 15 } ( B ) = 1.6 \pm 0.1 mag ) are very similar to those of SN 2005hk ( M _ { J } \sim - 17.7 mag , M _ { H } \sim -18.0 mag , and \Delta m _ { 15 } ( B ) \sim 1.6 mag ) , yet differ significantly from SNe 2008ha and 2010ae ( M _ { J } \sim - 14 - -15 mag and \Delta m _ { 15 } ( B ) \sim 2.4 - 2.7 mag ) .
The estimated rise time is 12.0 \pm 3.0 days , which is significantly shorter than that of SN 2005hk or any other Ia SNe .
The rapid rise indicates that the ^ { 56 } Ni distribution may extend into the outer layer or that the effective opacity may be lower than that in normal SNe Ia .
The late-phase spectrum exhibits broader emission lines than those of SN 2005hk by a factor of 6–8 .
Such high velocities of the emission lines indicate that the density profile of the inner ejecta extends more than that of SN 2005hk .
We argue that the most favored explosion scenario is a ‘ failed deflagration ’ model , although the pulsational delayed detonations is not excluded .