New approach could help scientists see inside neutron stars

Astrophysicists have tested possible approaches for determining the state of matter inside a neutron star. This is a tricky proposition.

Substitution can be a tricky art, especially when stars are involved.

When a massive star explodes, it can collapse into a very dense, mysterious object known as a neutron star. But neutron stars are too far and too small for even the most powerful telescopes to see inside, so scientists want to find ways to figure out what they’re made of.New research In , astrophysicists tested a potential approach to determining the state of matter inside a neutron star. (Familiar states of matter are solid, liquid, and gas.)

Scientists want to know the equation of state for a neutron star (EoS). This equation describes the properties of matter within an object or substance. However, obtaining the precise measurements needed to solve this equation for neutron stars, especially their radii, has not been easy.

So the researchers tested whether they could simplify their work by substituting another measurement for the radius of the neutron star. They looked at what scientists call the spectral peak frequencies of gravitational waves (space-time ripples) emitted when neutron stars merge into larger neutron stars. Dense clumps of stellar matter left behind after such collisions spew out enormous gravitational waves as they spin and rock back and forth at breakneck speeds. Signals from these waves can be picked up by sensitive instruments in gravitational-wave observatories such as the Laser Interferometer Gravitational-Wave Observatory (LIGO).

Astrophysicist and collaborator Elias Most of the Institute for Advanced Study of New Jersey says, “At least in principle, the spectral peak frequencies are calculated from gravitational-wave signals emitted from the shaking remnants of two merged neutron stars. You can, the authors of the new study said in a statement.

Scientists previously thought that f2 might represent the radius of a neutron star. However, a new study reveals that this is not always the case. For this substitution to work, scientists would instead have to include a second value related to the mass and radius of the neutron star.

The researchers hope the decision will help scientists shed light on the theory that neutrons in the cores of these stars decay into even smaller subatomic particles called quarks.

The research is described in an article published in The Astrophysical Journal Letters in July.

Quotation: https://www.space.com/neutron-star-equation-of-state