Fitting a SiII curve in a supernova spectra

In summary, The speaker is trying to determine the dark phase of a type Ia supernova by calculating the photosphere's velocity. They are attempting to find the redshift of the Si II absorption line in the spectra by fitting data points with a function. They have tried using a second degree polynomial but their Chi2 test was not successful. They are considering using a Gaussian, Voigt, or Lorenzian curve or using the graphical bisection method instead.
  • #1
rnielsen25
25
1
Hello guys (and girls),

I'm trying to determine the dark phase of a type Ia supernovae. In order to do that I need to calculate the photosphere's velocity.
So I'm trying to determine the redshift of the Si II in the spectra, by finding the minima in the absorption line. But what kind of function should i use for fitting my data points? Should i use a second degree polynomial, gauss curve, or is there an actual function describing this?

Here is an example of the Si II absorption "line": https://images.slideplayer.com/15/4805820/slides/slide_4.jpg

I tried fitting the curve, using a second degree polynomial. But my Chi2 test was too bad for some of my fits. So I was hoping there was a better function?
 
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  • #2
You could try a Gaussian , Viogt or Lorenzian curve but it might be better to just use the old fashioned graphical bisection method.

Regards Andrew
 

1. What is a SiII curve and why is it important in supernova spectra?

A SiII curve is a plot of the spectral features of Silicon II in a supernova. It is important because it can provide information about the chemical composition and evolution of the supernova, as well as the physical conditions of the explosion.

2. How is a SiII curve fitted in a supernova spectra?

A SiII curve is fitted by comparing the observed spectra of a supernova with theoretical models that include the spectral features of Silicon II. The parameters of the model, such as the velocity and abundance of Silicon II, are adjusted until the best fit is achieved.

3. What are the challenges in fitting a SiII curve in a supernova spectra?

The challenges in fitting a SiII curve include the complexity of the spectral features, which can be affected by various factors such as the temperature and density of the supernova, as well as the presence of other elements. Additionally, the quality of the observational data and the accuracy of the theoretical models can also impact the fitting process.

4. What information can be obtained from a fitted SiII curve in a supernova spectra?

A fitted SiII curve can provide information about the velocity and abundance of Silicon II in the supernova, which can help determine the type and stage of the explosion. It can also provide insights into the physical conditions of the supernova, such as the temperature and density.

5. How is a fitted SiII curve used in the study of supernovae?

A fitted SiII curve is used to classify supernovae and study their properties, such as their chemical composition and explosion mechanisms. It can also be used to compare different supernovae and track their evolution over time, providing valuable insights into the processes that govern these powerful cosmic events.

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