1 research outputs found
The carbon-rich type Ic supernova 2016adj in the iconic dust lane of Centaurus A: signatures of interaction with circumstellar hydrogen?
We present a comprehensive data set of supernova (SN) 2016adj located within
the central dust lane of Centaurus A. SN 2016adj is significantly reddened and
after correcting the peak apparent -band magnitude ()
for Milky Way reddening and our inferred host-galaxy reddening parameters
(i.e., and ), we estimate
it reached a peak absolute magnitude of . Detailed inspection of
the optical/NIR spectroscopic time-series reveals a carbon-rich SN Ic and not a
SN Ib/IIb as previously suggested in the literature. The NIR spectra shows
prevalent carbon-monoxide formation occurring already by +41 days past -band
maximum, which is days earlier than previously reported in the
literature for this object. Interestingly around two months past maximum, the
NIR spectrum of SN~2016adj begins to exhibit H features, with a +97~d medium
resolution spectrum revealing both Paschen and Bracket lines with absorption
minima of km/s, full-width-half-maximum emission velocities of
km/s, and emission line ratios consistent with a dense emission
region. We speculate these attributes are due to circumstellar interaction
(CSI) between the rapidly expanding SN ejecta and a H-rich shell of material
formed during the pre-SN phase. A bolometric light curve is constructed and a
semi-analytical model fit suggests the supernova synthesized 0.5 solar masses
of Ni and ejected 4.2 solar masses of material, though these values
should be approached with caution given the large uncertainties associated with
the adopted reddening parameters, possible CSI contamination, and known light
echo emission. Finally, inspection of Hubble Space Telescope archival data
yielded no progenitor detection.Comment: Submitted to A&A, comments are welcom