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Supernovae are the brightest phenomenon in the current universe. As massive stars die as supernovae, they briefly outshine the rest of the stars in their galaxy and are visible, at least once the light gets there, from across the universe. Until recently, astronomers thought they pretty much had supernovae figured out; they could either form from the direct collapse of a massive core or the tipping over the Chandrasekhar limit as a white dwarf accreted neighbor. These methods seemed to work well until astronomers began to discover “ultra-luminous” supernovae beginning with SN 2005ap. The usual suspects could not produce such bright explosions and astronomers began looking for new methods as well as new ultra-luminous supernovae to help understand these outliers. Recently, the automated sky survey Pan-STARRS netted two more.
Since 2010, the Panoramic Survey Telescope & Rapid Response System (Pan-STARR) has been conducting observations atop Mount Haleakala and is controlled by the University of Hawaii. Its primary mission is to search for objects that may pose a threat to Earth. To do this, it repeatedly scans the northern sky, looking at 10 patches per night and cycling through various color filters. While it has been very successful in this area, the observations can also be used to study objects that change on short timescales such as supernovae.
The first of the two new supernovae, PS1-10ky was already in the process of exploding as Pan-STARRS came into operation, thus, the brightness curve was incomplete since it was discovered near peak brightness and no data exists to catch it as it brightened. However, for the second, PS1-10awh, the team caught while in the process of brightening and have a complete light curve for the object. Combining the two, the team, led by Laura Chomiuk at the Harvard-Smithsonian Center for Astrophysics, was able to get a full picture of just how these titanic supernovae behave. And what’s more, since they were observed with multiple filters, the team was able to understand just how the energy was distributed. Additionally, the team was able to use other instruments, including Gemini, to get spectroscopic information.
The two new supernovae are very similar in many regards to the other ultra-luminous supernovae discovered previously, including SN 2010gx and SCP 06F6. All of these objects have been exceptionally bright with little absorption in their spectra. What little they did have was due to partially ionized carbon, silicon, and magnesium. The average peak brightness was -22.5 magnitudes where as typical core collapse supernovae peak around -19.5. The presence of these lines allowed astronomers to measure the expansion velocity for the new objects as 40,000 km/sec and place a distance to these objects as around 7 billion light years (previous ultra-luminous supernovae like these have been between 2 and 5 billion light years).
But what could power these leviathans? The team considered three scenarios. The first was radioactive decay. The violence of supernovae explosions injects atomic nuclei with additional protons and neutrons creating unstable isotopes which rapidly decay giving off visible light. This process is generally implicated in the fading out of supernovae as this decay process withers out slowly. However, based on the observations, the team concluded that it should not be possible to create sufficient amounts of the radioactive elements necessary to account for the observed brightness.
Another possibility was a rapidly rotating magnetar underwent a rapid change in its rotation. This sudden change would throw off large large chunks of material from the surface which could, in extreme cases, match the observed expansion velocity of these objects.
Lastly, the team considers a more typical supernova expanding into a relatively dense medium. In this case, the shockwave produced by the supernova would interact with the cloud around the star and the kinetic energy would heat the gas, causing it to glow. This too could reproduce many of the observed features of the supernova, but had the requirement that the star shed large amounts of material just before exploding. Some evidence is given for this as being a common occurrence in massive Luminous Blue Variable stars observed in the nearby universe. The team notes that this hypothesis may be tested by searching for radio emission as the shockwave interacted with the gas.
Here’s the relevant paper (PDF) on the subject:
Ultra-bright optical transients are linked with type Ic supernovae.
Here’s the relevant paper (PDF) on the subject:
Ultra-bright optical transients are linked with type Ic supernovae.
Super super, isn’t it called hypernova?
I have been pondering this a bit and maybe a possible model came to my mind. Suppose there is an ultra-dense core in a neutron star with mass near the Chandrasekhar limit for neutron stars ~ 3.2M_{sol}. The interior core will be a quark-gluon plasma. The quarks will then for immense pressure, but low temperature (low for a neutron star core) will enter into a state similar to BCS superconductivity. It works a bit like this. Suppose you have a fermion ?^?_i, where ? is the color index (QCD charge) for the quark, and i is the flavor index for up, down, strange quark types. The fermionic state is ?^?_i = q^?_i, where q means quark and this liberates me from a special symbol. The Cooper-pairing means there is a phase where the flavor and color indexes are locked. The expectation is then
where Q is an index for color or flavor that locks a color with a flavor. Here the
?_5 = i ?_1 ?_2 ?_3 ?_4,
which is the chiral Dirac matrix. This requires some understanding of the quaternion or spinor theory of fermions and what is sometimes called “Dirac-ology.”
This means that the phase of the interior will go Meissner, which means the chromo-magnetic field of the core is repelled. In ordinary superconductors this repels the magnetic field, which is why you can use superconductors to levitate things. The QCD field has components of a magnetic analogue for the electromagnetic interaction, or magnetic field. The onset of this phase in the interior of a neutron star would then adjust the energetic basis for the hydrostatic condition on the neutron star. The sudden repulsion of a coherent chromo-magnetic field might then carry huge amounts of bulk material with it. This would then be an explosion.
I made a point of the ?_5 matrix, for this is chiral. This theory breaks chiral symmetry. What is interesting is that QCD has a dual to anti-de Sitter spacetime. It did a little back of the envelope calculation a few weeks ago for the AdS_2, two dimensions near a black hole horizon in AdS_n, n > 2, and asked what happens when there is a Higgs-like potential on this. The theory becomes isomorphic to a quartic fermionic theory with Bogoliubov coefficients in superconductivity, and this breaks chiral symmetry. So this physics may have some duality with the underlying AdS structure of the universe or quantum gravity.
LC
I have been pondering this a bit and maybe a possible model came to my mind. Suppose there is an ultra-dense core in a neutron star with mass near the Chandrasekhar limit for neutron stars ~ 3.2M_{sol}. The interior core will be a quark-gluon plasma. The quarks will then for immense pressure, but low temperature (low for a neutron star core) will enter into a state similar to BCS superconductivity. It works a bit like this. Suppose you have a fermion ?^?_i, where ? is the color index (QCD charge) for the quark, and i is the flavor index for up, down, strange quark types. The fermionic state is ?^?_i = q^?_i, where q means quark and this liberates me from a special symbol. The Cooper-pairing means there is a phase where the flavor and color indexes are locked. The expectation is then
where Q is an index for color or flavor that locks a color with a flavor. Here the
?_5 = i ?_1 ?_2 ?_3 ?_4,
which is the chiral Dirac matrix. This requires some understanding of the quaternion or spinor theory of fermions and what is sometimes called “Dirac-ology.”
This means that the phase of the interior will go Meissner, which means the chromo-magnetic field of the core is repelled. In ordinary superconductors this repels the magnetic field, which is why you can use superconductors to levitate things. The QCD field has components of a magnetic analogue for the electromagnetic interaction, or magnetic field. The onset of this phase in the interior of a neutron star would then adjust the energetic basis for the hydrostatic condition on the neutron star. The sudden repulsion of a coherent chromo-magnetic field might then carry huge amounts of bulk material with it. This would then be an explosion.
I made a point of the ?_5 matrix, for this is chiral. This theory breaks chiral symmetry. What is interesting is that QCD has a dual to anti-de Sitter spacetime. It did a little back of the envelope calculation a few weeks ago for the AdS_2, two dimensions near a black hole horizon in AdS_n, n > 2, and asked what happens when there is a Higgs-like potential on this. The theory becomes isomorphic to a quartic fermionic theory with Bogoliubov coefficients in superconductivity. So this physics may have some duality with the underlying AdS structure of the universe or quantum gravity.
LC
I have a bit of an update on this idea of a Meissner effect. The color-flavor locking (CFL) does break the SU(3) symmetry of the QCD field. I was thinking that the Messier effect was with the magnetic analogue of the QCD field. This does happen, but the field is actually not that long range outside of the QCD vacuum bubble. The calculation leads to the fact that the U(1) field of electromagnetism is broken as well. So the long range ordinary magnetic field goes Meissner as well.
The astrophysics, in a meatball setting, would then be that a neutron star is in an orbit around another more ordinary star. This is taking material off the star by tidal forces and the neutron star increases its mass. Then at some mass lower than or equal to 3.2 solar mass the core of the neutron star enters into this CFL phase. The magnetic field of a neutron star is on the order of 10^{12} Gauss, where this field is then repelled by the CFL phase transition. The energy density for a magnetic field is e = B^2/2?, ? is the permeability which for intense fields and highly conductive media tends to unit or ? = 1. so the magnetic field energy density is about 10^{24}j/m^3. A neutron star is about 20km in radius, or it has a volume of 83800m^3. This means the magnetic energy of the neutron star is about 4×10^{28}j.
The onset of Meissner collapses ? = 0 and the magnetic energy collapses to zero in the core, and rises enormously in the region around the core. The expression for the magnetic energy density then has a “zero over zero” division problem, which at this time I don’t know how to calculate in a limit or l’Hospital’s rule. The physical ansatz I use then is that the core in the CFL state implodes into a black hole. This collapse then releases gravitational potential energy that drives the magnetic field outwards. In just using Newtonian gravity I assume that M ~ M_{sol} of the neutron star core implodes from a radius of 10km to 1km and the self-potential energy is
?V = GM^2(1/r – 1/r_0) =~ 6.7×10^{-11}10^{60}10^{-4}j =~ -10^{46}j
This is the decrease in gravitational potential due to collapse and conservation of energy means an equal amount of energy is imparted to the magnetic field which expels the rest of the neutron star material.
Think of the magnetic field in the core as being what keeps the core from collapsing further. Once the CFL phase set in the magnetic field is repelled from the core and the Fermi statistics which prevent further collapse are annulled. These are the “springs” which keep the core from becoming a black hole. The onset of the Meissner effect detaches the springs which go flying outwards and the core implodes.
A type Ia supernova liberates 4×10^{44} joules, and this is one to two order of magnitude more energy than a type Ia SN. There are some curious predictions which should be made. One is the appearance of dwarf black holes of 1.5 to 2 solar masses. The other is that if this type of SN is observed to occur in our neighborhood the rapid adjustment of this magnetic field should produce a considerable electromagnetic pulse signature.
LC
O_o
i truly wish i could comprehend the math on your level.