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L_Universe due to SNII Neutrinos = 322 * L_Universe?



 
 
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  #1  
Old December 14th 16, 07:57 AM posted to sci.astro.research
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Default L_Universe due to SNII Neutrinos = 322 * L_Universe?

In SLAC lecture at

https://www.youtube.com/watch?v=3DHiCRTUxgwPY

Public Lecture | Supernovas: Gravity-powered Neutrino Bombs Alex
Friedland comments that for a snII, the power emitted in neutrinos
for about 10 seconds outshines all the L of stars in entire universe,
at about time: 36:45.

He states that the neutrino burst is 100x more powerful than the
visible explosion, and that during the 10 seconds neutrinos are
being emitted, the power is greater than visible emissions in all
stars in the entire universe. He also mentions 10% of mass of
collapsed core is converted to energy

There are around 31E6 seconds per year. About 1 SN per galaxy per
100 years. Is this about right for SNII, especially in the past?

And about 100E9 galaxies in visible universe. So that means about
1 billion SN per year in the now visible universe. But that means
the Luminosity from neutrinos is

L_neutrinos/Universe = L_universe * 10s/SN * 1SN / 100yrGal *
1yr/31E6s * 100E9Gal/Univ

so, L_neutrinos from SNII explosions = 322 L_universe starlight

Really?

Is L from SNIA similarly large?
  #2  
Old December 14th 16, 09:52 PM posted to sci.astro.research
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Default L_Universe due to SNII Neutrinos = 322 * L_Universe?

On Wednesday, December 14, 2016 at 1:57:51 AM UTC-5, wrote:
In SLAC lecture at

https://www.youtube.com/watch?v=3DHiCRTUxgwPY

Public Lecture | Supernovas: Gravity-powered Neutrino Bombs Alex
Friedland comments that for a snII, the power emitted in neutrinos
for about 10 seconds outshines all the L of stars in entire universe,
at about time: 36:45.

He states that the neutrino burst is 100x more powerful than the
visible explosion, and that during the 10 seconds neutrinos are
being emitted, the power is greater than visible emissions in all
stars in the entire universe. He also mentions 10% of mass of
collapsed core is converted to energy

AFAIK, this is not news. Have you tried searching the relevant
literature on core collapse SNe?

There are around 31E6 seconds per year. About 1 SN per galaxy per
100 years. Is this about right for SNII, especially in the past?


I doubt it. Core collapse SNe are exceedingly rare in early-type
galaxies ("ellipticals") because there are no stars massive enough.
Type Ia SNe however ...

And about 100E9 galaxies in visible universe. So that means about
1 billion SN per year in the now visible universe. But that means
the Luminosity from neutrinos is

L_neutrinos/Universe = L_universe * 10s/SN * 1SN / 100yrGal *
1yr/31E6s * 100E9Gal/Univ

so, L_neutrinos from SNII explosions = 322 L_universe starlight

Really?


No. Galaxies are not at all like electrons; they have a huge range
of sizes, masses, and (most important) distributions of stars by
mass.
Is L from SNIA similarly large?


Why not do some reading up on supernovae? The answers aren't all
that hard to find :-)
  #3  
Old December 24th 16, 11:15 AM posted to sci.astro.research
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Default L_Universe due to SNII Neutrinos = 322 * L_Universe?

On Wednesday, December 14, 2016 at 12:52:12 PM UTC-8,
wrote:

[Moderator's note: Inappropriate comments deleted. -P.H.]

I doubt it. Core collapse SNe are exceedingly rare in early-type
galaxies ("ellipticals") because there are no stars massive enough.
Type Ia SNe however ...


This is not correct as far as I know.

Today, in the modern universe, sure this is correct. But I was probing
back to initial star formation. So, many of the stars that formed into
the earliest galaxies came from star fields / formation regions, and
within those were many SNII explosions. The reason we don't see SNII
in elliptical galaxies today is just that they are (for the most part)
no longer forming new stars

After the dark ages, during the era of initial star formation, SNII were
common and the largest stars were likely larger than today with
extremely short lifetimes, helping explain why finding type III stars is
so difficult to day. Early SNII polluted the gas of the universe with
heavy elements.

So the statement that early type galaxies don't host SNII is correct in
the modern universe but not in the early universe when the first stars
were born.

AFAIK.

rt

 




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