Space Grant Consortium - University of Wisconsin - Green Bay

or galactic effects. Once the data were flagged, they were calibrated since the data were
collected by several radio dishes of the telescope. The calibration process started first with
a task called SETJY that set the flux (brightness per unit area) of the primary calibrator
(a very bright, nearly constant radio source). The secondary calibrator was then adjusted
relative the the primary calibrator using the task SETJY. Next the phases were calibrated
by the task CALIB. Finally, the task CLCAL applied the calibrations to the data set.
After calibrating the data, the data were imaged and the images were “cleaned” to reduce
noise and other effects. Several calculations could then be made on the final images, such
as calculating the spectral luminosity. The results of the calculations were then placed in a
spreadsheet.
After processing all the data sets for a SN, the log of the spectral luminosity vs. the log of
the time since explosion for each data period were graphed, thus producing what is called a
light curve. The light curves were then used to make determinations about the SN.
Results
SN 2008ax in NGC 4490 was found to have reached its peak at around 10 days after the
initial blast and faded on the 22 GHz band after about 20 days (Figure 1). Most SN do
not reach their peak until at least 500 days after the initial blast and do not fade until after
several thousand days (cf. Figure 2). Further SN 2008ax exhibits irregular development
after its peak, especially on the 8.46 GHz and 4.86 GHz bands, where the data points show
irregular dips and rises that do not correspond to the normal parameterized curve.
SN 2008bo in NGC 6643 is very faint in the radio spectrum, far away and early in its
progression as a SN. It appears that SN 2008bo may be similar to SN 2008ax, since it is
progressing quickly (Figure 4). Further, SN 2008bo has brighter X-ray emissions than SN
2008ax, since SN 2008bo is fairly isolated and SN 2008ax is near a bright X-ray source.
Conclusions
The deviance from the parameterized curve and the short lifespan of SN 2008ax are similar
to those of SN 2001ig (Figure 5). The similarities may indicate that SN 2008ax is not
unique, rather part of a new subclass of type IIb SNe. The fluctuations in the light curve by
SN 2008ax and SN 2001ig have been attributed to the presence of a companion star. The
gravitational field of the companion star cause ripples in the CSM of the SN progenitor star.
When the SN progenitor star explodes, the resulting radio wave emissions deviate from the
standard model at places where the companion star’s gravitational field caused ripples in
the CSM (Figure 7).
4