Post-maximum near infrared spectra of SN 2014J: A search for interaction   signatures
  We present near infrared (NIR) spectroscopic and photometric observations of the nearby Type Ia SN 2014J. The seventeen NIR spectra span epochs from +15.3 to +92.5 days after $B$-band maximum light, while the $JHK_s$ photometry include epochs from $-$10 to +71 days. This data is used to constrain the progenitor system of SN 2014J utilizing the Pa$\beta$ line, following recent suggestions that this phase period and the NIR in particular are excellent for constraining the amount of swept up hydrogen-rich material associated with a non-degenerate companion star. We find no evidence for Pa$\beta$ emission lines in our post-maximum spectra, with a rough hydrogen mass limit of $\lesssim$0.1 $M_{\odot}$, which is consistent with previous limits in SN 2014J from late-time optical spectra of the H$\alpha$ line. Nonetheless, the growing dataset of high-quality NIR spectra holds the promise of very useful hydrogen constraints. 
D. J. Sand, E.Y. Hsiao, D.P.K. Banerjee, G.H. Marion, T. R. Diamond,   V. Joshi, J.T. Parrent, M. M. Phillips, M. D. Stritzi...
astro-ph.GA astro-ph.HE