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Register a new userMapping Circumstellar Matter with Polarized Light - The Case of Supernova 2014J in M82
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Optical polarimetry is an effective way of probing the environment of supernova for dust. We acquired linear HST ACS/WFC polarimetry in bands $F475W$, $F606W$, and $F775W$ of the supernova (SN) 2014J in M82 at six epochs from $sim$277 days to $sim$1181 days after the $B$-band maximum. The polarization measured at day 277 shows conspicuous deviations from other epochs. These differences can be attributed to at least $sim$ 10$^{-6} M_{odot}$ of circumstellar dust located at a distance of $sim5times10^{17}$ cm from the SN. The scattering dust grains revealed by these observations seem to be aligned with the dust in the interstellar medium that is responsible for the large reddening towards the supernova. The presence of this circumstellar dust sets strong constraints on the progenitor system that led to the explosion of SN,2014J; however, it cannot discriminate between single- and double-degenerate models.
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We present multiple-epoch measurements of the size and surface brightness of the light echoes from supernova (SN) 2014J in the nearby starburst galaxy M82. Hubble Space Telescope (HST) ACS/WFC images were taken ~277 and ~416 days after B-band maximum in the filters F475W, F606W, and F775W. Observations with HST WFC3/UVIS images at epochs ~216 and ~365 days (Crotts 2015) are included for a more complete analysis. The images reveal the temporal evolution of at least two major light-echo components. The first one exhibits a filled ring structure with position-angle-dependent intensity. This radially extended, diffuse echo indicates the presence of an inhomogeneous interstellar dust cloud ranging from ~100 pc to ~500 pc in the foreground of the SN. The second echo component appears as an unresolved luminous quarter-circle arc centered on the SN. The wavelength dependence of scattering measured in different dust components suggests that the dust producing the luminous arc favors smaller grain sizes, while that causing the diffuse light echo may have sizes similar to those of the Milky Way dust. Smaller grains can produce an optical depth consistent with that along the supernova-Earth line of sight measured by previous studies around maximum light. Therefore, it is possible that the dust slab, from which the luminous arc arises, is also responsible for most of the extinction towards SN 2014J. The optical depths determined from the Milky Way-like dust in the scattering matters are lower than that produced by the dust slab.
We present the measurement of the size and surface brightness of the expanding light echoes from supernova (SN) 2014J in the nearby starburst galaxy M82. Hubble Space Telescope (HST) ACS/WFC images were taken ~277 and ~416 days (after the time of B-band maximum light) in the filters F475W, F606W, and F775W, each combined with the three polarizing filters: POL0V, POL60V, and POL120V. The two epochs imaging reveals the time evolution of at least two major echoes. Three concentric bright regions between position angles (PA, 0^{circ} from North, counterclockwise). 80^{circ} ~ 170^{circ} have projected radius of 0.60 on the sky on ~277 days and expanding to 0.75 on ~416 days, corresponding to scattering materials at a foreground distance of 222pm37 pc. Another fainter but evident light echo extending over a wide range of PA has radii of 0.75 and 0.96 on ~277 and ~416 days. This corresponds to scattering material at a foreground distance of 367pm61 pc. Multiple light echoes with S/N > 2.5 reside at smaller radii on ~277 days but become less significant on ~416 days indicating a complex structure of foreground interstellar medium (ISM). The light echo shows bluer color than predicted under a Rayleigh scattering case. We also found the light echo brightened from V_{echo}=21.68pm0.07 on 2014 September 5, to V_{echo}=21.05pm0.08 on 2014 November 6, suggesting an enhancement of echoing materials at different distances projected on to the plane of the sky.
We report observations of the bright M82 supernova 2014J serendipitously obtained with the Kilodegree Extremely Little Telescope (KELT). The SN was observed at high cadence for over 100 days, from pre-explosion, to early rise and peak times, through the secondary bump. The high cadence KELT data with high S/N is completely unique for SN 2014J and for any other SNIa, with the exception of the (yet) unpublished Kepler data. Here, we report determinations of the SN explosion time and peak time. We also report measures of the smoothness of the light curve on timescales of minutes/hours never before probed, and we use this to place limits on energy produced from short-lived isotopes or inhomogeneities in the explosion or the circumstellar medium. From the non-observation of significant perturbations of the light curves, we derive a 3sigma upper-limit corresponding to 8.7 x 10^36 erg/s for any such extra sources of luminosity at optical wavelengths.
The very nearby Type Ia supernova 2014J in M82 offers a rare opportunity to study the physics of thermonuclear supernovae at extremely late phases ($gtrsim$800 days). Using the Hubble Space Telescope (HST), we obtained six epochs of high precision photometry for SN 2014J from 277 days to 1181 days past the $B-$band maximum light. The reprocessing of electrons and X-rays emitted by the radioactive decay chain $^{57}$Co$rightarrow ^{57}$Fe are needed to explain the significant flattening of both the $F606W$-band and the pseudo-bolometric light curves. The flattening confirms previous predictions that the late-time evolution of type Ia supernova luminosities requires additional energy input from the decay of $^{57}$Co (Seitenzahl et al. 2009). By assuming the $F606W$-band luminosity scales with the bolometric luminosity at $sim$500 days after the $B-$band maximum light, a mass ratio $^{57}$Ni/$^{56}$Ni$sim$0.065$_{-0.004}^{+0.005}$ is required. This mass ratio is roughly $sim$3 times the solar ratio and favors a progenitor white dwarf with a mass near the Chandrasekhar limit. A similar fit using the constructed pseudo-bolometric luminosity gives a mass ratio $^{57}$Ni/$^{56}$Ni$sim$0.066$_{-0.008}^{+0.009}$. Astrometric tests based on the multi-epoch HST ACS/WFC images reveal no significant circumstellar light echoes in between 0.3 pc and 100 pc (Yang et al. 2017) from the supernova.
We present optical and ultraviolet (UV) photometry and spectra of the very nearby and highly reddened supernova (SN) 2014J in M82 obtained with the Swift Ultra-Violet/Optical Telescope (UVOT). Comparison of the UVOT grism spectra of SN~2014J with Hubble Space Telescope observations of SN2011fe or UVOT grism spectra of SN~2012fr are consistent with an extinction law with a low value of R_V~1.4. The high reddening causes the detected photon distribution in the broadband UV filters to have a much longer effective wavelength than for an unreddened SN. The light curve evolution is consistent with this shift and does not show a flattening due to photons being scattered back into the line of sight. The light curve shapes and color evolution are inconsistent with a contribution scattered into the line of sight by circumstellar dust. We conclude that most or all of the high reddening must come from interstellar dust. We show that even for a single dust composition, there is not a unique reddening law caused by circumstellar scattering. Rather, when considering scattering from a time-variable source, we confirm earlier studies that the reddening law is a function of the dust geometry, column density, and epoch. We also show how an assumed geometry of dust as a foreground sheet in mixed stellar/dust systems will lead to a higher inferred R_V. Rather than assuming the dust around SNe is peculiar, SNe may be useful probes of the interstellar reddening laws in other galaxies.
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