Alternate Diagrams: MSP's
- FP(MAX): Fast pulsar transitioning from spinning up to spinning down
- FP(+): Fast pulsar spinning up
- FP(-): Fast pulsar spinning down
- NS: Neutron star
- NS(0): Neutron star with no angular momentum
- GS: Giant star
- GSE: Giant star explosion
- SNE: Supernova event
- SNR: Supernova remnant
Note: The differing processes are colored consistently throughout the six diagrams to distinguish them in the diagrams. The Processes in green are observed. Those in light and dark blue are predicted by NS Creation. Those in red follow from NS Capture.
In the case of the crab nebula we have observed a FP(-) in the presence of SNR. This is shown in the diagram above. The Crab Pulsar rotates roughly 30 times a second and is observed to be slowing down from its original predicted 60 times a second into a non-spinning NS. This pulsar and those like it are found in the remnants class of the P/PDot diagram.
NS Creation explains this by postulating the SNR are the result of a GS collapsing under its own weight and expelling its outer layers. The remnants would consist of a cloud of gas and dust surrounding dense core of neutrons supported by neutron degeneracy pressure. We call this core the neutron star. This is shown below as Process 1.
Process 1: Isolated NS Creation
Note: The vertical axis on these diagrams corresponds to spin rate.
If this can happen to a GS in isolation, we expect it can happen to a GS in a binary with another star. This is shown below as process 2 where both stars are GSs and illustrated here.
Process 2: NS Creation in a Binary
In order to explain a class of pulsars called MSPs which spin hundreds of times a second, there had to be proposed a mechanism to spin neutron stars up into MSPs. This process occurs as their orbit begins “circularizing.” The mechanism by which this occurs is tidal deformation of the GS or, in other words, the outer edges of the GS are distended toward the NS and the increased gravity due to the shortened distance from the tidal bulge circularizes the orbit.
Once the orbit has been circularized sufficiently, the NS begins accumulating matter from the GS which contributes, by conservation of angular momentum, to “spinning up” the NS. This process can be viewed in detail here as diagram 1 as well in this simulation.
Eventually, the FP evaporates the GS with tidal winds as shown here in a process we’ve labelled a GSE. All that is left is a FP spinning down in the presence of SNRs which eventually dissipate. The question of the identification of SNRs and GSRs will be discussed in further detail on a future page.
Process 3: Creation of MSPs
Where does the NS(0) + GS binary come from?
Assuming the above is true, we can combine processes two and three to answer the above question. One GS in the binary implodes into a FP, then spins down into a NS while remaining in the binary. This can be seen in process 4 below.
Process 4: Processes 2 & 3 combined
If the GS is small enough, it is possible that the force from the implosion blows the newly created FP the necessary distance to prevent the accumulation of matter from the GS which allows it to spin down as shown here, but since NSs tend to spin up into FPs in the presence of GSs, this process would have to be quite rare and short-lived.
In other words, the states in row 3, column 2 and row 3, column 3 are in contradiction. Those in column 3 are observed, so we propose another mechanism by which the state in row 4, column 3 may be actualized.
This new mechanism is termed NS Capture. In NS Capture, a NS and GS are originally unbound and undergo process called tidal capture. This is similar to the circularization mentioned above.
If the unbound NS approaches the GS within a certain distance called the impact parameter, it will deform the surface of the GS causing an increase of the gravitational force between them and the capture of the NS. Now in a binary, the orbit will proceed to circularize and follow the above mentioned processes. This can seen in process 5 below where the unbound NS and GS have been added in row 5, column 3.
Process 5: NS Capture
Finally, below, we have combined all possible processes. This is simply the combination of Processes 4 (columns 1 & 2), 5 (columns (3&4) and 1 (column 5).