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Register a new userPhotometric, polarimetric, and spectroscopic studies of the luminous, slow-decaying Type Ib SN 2012au
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Optical, near-infrared (NIR) photometric and spectroscopic studies, along with the optical imaging polarimetric results for SN 2012au, are presented in this article to constrain the nature of the progenitor and other properties. Well-calibrated multiband optical photometric data (from $-$0.2 to +413 d since $B$-band maximum) were used to compute the bolometric light curve and to perform semi-analytical light-curve modelling using the $texttt{MINIM}$ code. A spin-down millisecond magnetar-powered model explains the observed photometric evolution of SN 2012au reasonably. Early-time imaging polarimetric follow-up observations ($-$2 to +31 d) and comparison with other similar cases indicate signatures of asphericity in the ejecta. Good spectral coverage of SN 2012au (from $-$5 to +391 d) allows us to trace the evolution of layers of SN ejecta in detail. SN 2012au exhibits higher line velocities in comparison with other SNe Ib. Late nebular phase spectra of SN 2012au indicate a Wolf$-$Rayet star as the possible progenitor for SN 2012au, with oxygen, He-core, and main-sequence masses of $sim$1.62 $pm$ 0.15 M$_odot$, $sim$4$-$8 M$_odot$, and $sim$17$-$25 M$_odot$, respectively. There is a clear absence of a first overtone of carbon monoxide (CO) features up to +319 d in the $K$-band region of the NIR spectra. Overall analysis suggests that SN 2012au is one of the most luminous slow-decaying Type Ib SNe, having comparatively higher ejecta mass ($sim$4.7$-$8.3 M$_odot$) and kinetic energy ($sim$[4.8 $-$ 5.4] $times$ 10$^{51}$ erg). Detailed modelling using $texttt{MESA}$ and the results obtained through $texttt{STELLA}$ and $texttt{SNEC}$ explosions also strongly support spin-down of a magnetar with mass of around 20 M$_odot$ and metallicity Z = 0.04 as a possible powering source of SN 2012au.
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We present a set of photometric and spectroscopic observations of a bright Type Ib supernova SN 2012au from -6d until ~+150d after maximum. The shape of its early R-band light curve is similar to that of an average Type Ib/c supernova. The peak absolute magnitude is M_R=-18.7+-0.2 mag, which suggests that this supernova belongs to a very luminous group among Type Ib supernovae. The line velocity of He I {lambda}5876 is about 15,000 km/s around maximum, which is much faster than that in a typical Type Ib supernova. From the quasi-bolometric peak luminosity of (6.7+-1.3)x10^(42) erg/s, we estimate the Ni mass produced during the explosion as ~0.30 Msun. We also give a rough constraint to the ejecta mass 5-7 Msun and the kinetic energy (7-18)x10^(51) erg. We find a weak correlation between the peak absolute magnitude and He I velocity among Type Ib SNe. The similarities to SN 1998bw in the density structure inferred from the light curve model as well as the large peak bolometric luminosity suggest that SN 2012au had properties similar to energetic Type Ic supernovae.
This paper presents data and analysis of SN 2010kd, a low-redshift ($z = 0.101$) H-deficient superluminous supernova (SLSN), based on ultraviolet/optical photometry and optical spectroscopy spanning between $-$28 and +194 days relative to $mathit{B}$ band maximum light. The $mathit{B}$ band light curve comparison of SN 2010kd with a subset of well-studied SLSNe I at comparable redshifts indicates that it is a slow-decaying PTF12dam like SLSN. Analytical light-curve modeling using the $mathtt{Minim}$ code suggests that the bolometric light curve of SN 2010kd favors circumstellar matter interaction for the powering mechanism. $mathtt{SYNAPPS}$ modeling of the early-phase spectra does not identify broad H or He lines, whereas the photospheric-phase spectra are dominated by O I, O II, C II, C IV and Si II, particularly, presence of both low and high-velocity components of O II and Si II lines. The nebular-phase spectra of SN 2010kd are dominated by O I and Ca II emission lines similar to those seen in other SLSNe I. The line velocities in SN 2010kd exhibit flatter evolution curves similar to SN 2015bn but with comparatively higher values. SN 2010kd shows a higher single-zone local thermodynamic equilibrium temperature in comparison to PTF12dam and SN 2015bn, and it has an upper O I ejected mass limit of $sim 10~M_odot$. The host of SN 2010kd is a dwarf galaxy with a high star-formation rate ($sim 0.18 pm 0.04~M_odot$ yr$^{-1}$) and extreme emission lines.
We present an optical spectrum of the energetic Type Ib supernova (SN) 2012au obtained at an unprecedented epoch of 6.2 years after explosion. Forbidden transition emission lines of oxygen and sulfur are detected with expansion velocities of 2300 km/s. The lack of narrow H Balmer lines suggests that interaction with circumstellar material is not a dominant source of the observed late-time emission. We also present a deep Chandra observation that reveals no X-ray emission down to a luminosity of L_X < 2 x 10^{38} erg/s (0.5-10 keV). Our findings are consistent with the notion that SN 2012au is associated with a diverse subset of SNe, including long-duration gamma-ray burst SNe and superluminous SNe, harboring pulsar/magnetar wind nebulae that influence core-collapse explosion dynamics on a wide range of energy scales. We hypothesize that these systems may all evolve into a similar late-time phase dominated by forbidden oxygen transitions, and predict that emission line widths should remain constant or broaden a few per cent per year due to the acceleration of ejecta by the pulsar/magnetar bubble.
We present the photometric and spectroscopic studies of a Type Ib SN 2015ap and a Type Ic SN 2016P. SN 2015ap is one of the bright (M$_{V}$ = $-$18.04 mag) Type Ib while SN 2016P lies at an average value among the Type Ic SNe (M$_{V}$ = $-$17.53 mag). Bolometric light curve modelling of SNe 2015ap and 2016P indicates that both the SNe are powered by $^{56}$Ni + magnetar model with $^{56}$Ni masses of 0.01 M$_{odot}$ and 0.002 M$_{odot}$, ejecta masses of 3.75 M$_{odot}$ and 4.66 M$_{odot}$, spin period P$_{0}$ of 25.8 ms and 36.5 ms and magnetic field B$_{p}$ of 28.39 $times$ 10$^{14}$ Gauss and 35.3 $times$ 10$^{14}$ Gauss respectively. The early spectra of SN 2015ap shows prominent lines of He with a W feature due to Fe complexes while other lines of Mg II, Na I and Si II are present in both SNe 2015ap and 2016P. Nebular phase [O I] profile indicates an asymmetric profile in SN 2015ap. The [O I]/[Ca II] ratio and nebular spectral modelling of SN 2015ap hints towards a progenitor mass between 12 $-$ 20 M$_{odot}$.
We present an extensive ($sim$ 1200 d) photometric and spectroscopic monitoring of the Type IIn supernova (SN) 2012ab. After a rapid initial rise leading to a bright maximum (M$_{R}$ = $-$19.39 mag), the light curves show a plateau lasting about 2 months followed by a steep decline up to about 100 d. Only in the $U$ band the decline is constant in the same interval. At later phases, the light curves remain flatter than the $^{56}$Co decline suggesting the increasing contribution of the interaction between SN ejecta with circumstellar material (CSM). Although heavily contaminated by emission lines of the host galaxy, the early spectral sequence (until 32 d) shows persistent narrow emissions, indicative of slow unshocked CSM, and the emergence of broad Balmer lines of hydrogen with P-Cygni profiles over a blue continuum, arising from a fast expanding SN ejecta. From about 2 months to $sim$1200 d, the P-Cygni profiles are overcome by intermediate width emissions (FWHM $sim 6000$ kms), produced in the shocked region due to interaction. On the red wing a red bump appears after 76 d, likely a signature of the onset of interaction of the receding ejecta with the CSM. The presence of fast material both approaching and then receding is suggestive that we are observing the SN along the axis of a jet-like ejection in a cavity devoid of or uninterrupted by CSM in the innermost regions.
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