Questions tagged [pulsars]

A highly magnetised rotating compact star (black hole, neutron star, white dwarf) that emits beams of electromagnetic radiation out of its magnetic poles.

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How can a pulsar slow down?

I saw in some astronomy textbooks that pulsars gradually slow down due to the loss of energy by its radiation. I wonder why this is possible? Although the radiation is now not thermal but in the form ...
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Doppler shift in period of a pulsar

The paper Discovery of a Pulsar in a Binary System says that the reason this pulsar's period is not constant in time is due to Doppler shift from the pulsar's orbital motion. I am accustomed to ...
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Thomas Precession on Neutron Stars

We know that Thomas Precession is a relativistic correction that is applied to a particle spin that adds an angular velocity to the spin of the particle that moves along a curvilinear orbit linked to ...
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If a pulsar moves with a high velocity should the pulses from both poles be not paralel?

If a pulsar moves with a high velocity should the pulses from both poles be not paralel to each other? Should they as a continuum form a an angle between them exactly at the very location of the ...
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Is a pulsar EM-radiation affected by diffraction?

Is a pulsar EM-radiation affected by diffraction? As I understand gaussean beam theory there should exist different diffraction or if You want diffusion angles for different wavelengths, for example ...
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Is redshift acting on pulses from pulsars and how it changes the diffraction of the pulse and so its brightness?

Is redshift acting on pulses from pulsars and how it changes the diffraction of the pulse and so its brightness? As far as I know the diffraction becomes higher while wavelength increases as moving ...
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Are astrophysical jets at the poles of equal strength?

I know black hole and neutron star can eject subatomic charged particles as astrophysical jet, I am comparing our sun chaotic magnetic field vs those in black hole jet and pulsars. The former ...
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How do pulsars and magnetars emit lots of radiation?

Firstly I thought that Pulsars are rapidly rotating, highly magnetic compact stars. The rotating magnetic field of a pulsar acts as a generator, accelerating energetic charged particles that then ...
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How are the units (seconds) of the dispersion constant determined?

The following is taken from Cordes [1] on pulsar astronomy. The dispersive time delay [is] $$t_\mathrm{DM}=\frac{e^2}{2\pi m_e c} \frac {\int_0^Dds \text{ } n_e}{\nu^2} = 4.15\text{ms} \text{ DM } \...
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What is superradiance?

What is superradiance? I came across this term recently (used widely to explain fast radio bursts). After googling a bit, what I understand is: When several atoms are confined in a very small area and ...
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Is the sound of pulsars converted radio waves, or actual sound that's has been put into a loudspeaker?

Do neutron stars produce sound? In the answer to the above question, it has been mentioned that: 'The pulsar signal is often transformed directly into an audible signal by simply feeding it to a ...
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Where can I hear the trapped sounds inside a pulsar?

I have been searching for an audible track of stellar oscillations inside a pulsar, but I don't seem to find what I want. No, I am not asking about the radio waves emitted that have been converted ...
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Why do high frequency radio telescope observations require precise localization?

Why do high frequency radio observations, particularly of transient phenomenon such as Fast Radio Burst and Pulsars, require increasingly precise localization with increasingly high frequency?
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Rotating pulsars about maximum moment of inertia

Pulsars rotate very fast. Its axis of rotation may be or may not be aligned with the axis of the radiation beam. But, you see with respect to the Dzhanibekov effect, the pulsar should be rotating with ...
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Difference between gravitational wave detectors

There are a lot of different gravitational wave detectors and they all have their own wave period and frequency they operate at. This picture shows that The last three (pulsar timing, space ...
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Are there any patterns in the locations of pulsars in our universe?

Are there any particular places pulsars are distributed? If so, why? Any information to links and articles will also be appreciated. I just want to understand more about pulsars and if there are any ...
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What is the relationship between a pulsars period and the frequency? [closed]

If I measured the period at several of frequencies for a pulsar using a radio telescope what relationship should i see?
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Why were pulsars not discovered in the visual spectrum?

In 1967, the first pulsar was discovered at a radio observatory in Cambridge. Radio astronomy started around the 1930s, but astronomy in the visible part of the spectrum had been done for a long time ...
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What is the propeller phase of a pulsar?

I am studying this paper: Isolated thermal neutron stars, soft gamma-ray repeaters and anomalous X-ray pulsars: propellers and early accretors with conventional magnetic fields? arxiv:astro-...
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What is "Radiation damping stronger than inertia."

I'm reading a paper on creating gamma rays in a lab and I've come across a phrase I simply don't understand; "Radiation Damping Stronger Than Inertia". As I understand it radiation damping is just ...
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How to understand the Einstein delay?

In pulsar timing, one of the post-Keplerian parameters is the Einstein delay $\Delta E$. The total `flight time' of a photon emitted from a pulsar is then given by $$ \Delta t = \Delta R + \Delta E + \...
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Einstein@Home - what is the purpose of "gamma pulsar binary search" tasks?

I participate in Einstein@Home program. My question is - what is the purpose of "gamma pulsar binary search" tasks? What signatures are being searched? How gamma pulsar binaries can help in study ...
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How did Jocelyn Bell aim her radio telescope (phased array)?

In 1967 Jocelyn Bell discovered pulsars using the Cambridge University radio telescope - a two hectare field of posts and wires. The pulsar was found to be in the constellation Vulpecula. How did ...
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How does the delay of pulsar signals prove that gravity travels at the speed of light?

In the Hulse-Taylor binary pulsar system, the orbit of the two neutron stars results in the warping of space time causing the pulses to arrive earlier and later because of the longer distance ...
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How is EMR "delayed" in pulsar dispersion if light speed is constant?

Pulsars emit one pulse that arrives at later times at lower frequencies. The reason I have read is: Since radio waves are a very low frequency form of light/electromagnetic radiation (ie photons), ...
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Radio vs X-ray pulsar timing

The detection and timing of pulsars is a common goal in astronomy (eg.1, 2). Typically these observations are done in the radio. I appreciate that observations are taken in the X-ray as well, but is ...
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How to derive the inclination angle evolution of a dipolar pulsar?

The spin-down evolution of a simple vacuum pulsar model is well known. Using the power output of radiation emission of a rotating magnetic dipole, we get the following equation (assuming that the ...
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Where does the 10 km of neutrons stars comes from? [duplicate]

Neutrons stars are known to have a radius of about 10 km to 15 km. Where that size comes from ? How to theoretically derive that number, using Newton's theory of gravity ? I know the magnetic flux ...
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How to understand the units of Dispersion Measure?

In astrophysics and pulsar astronomy, a typical quantity is the dispersion measure or DM, which is the integral of the electron number density along the line of sight, $$ DM = \int_0^d n \, dl$$ up ...
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Due to relativity, does the surface of a pulsar have less area than the layer beneath it?

A pulsar or spinning neutron star can reach relativistic angular velocities. Special relativity asserts that objects traveling near the speed of light contract in length. Therefore, it seems ...
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Effect on pulsar signals of Earth's orbit

Do pulsar signals 'change' with our orbit? For example, if a pulsar was in Sagittarius, our orbit would have us 300 million km closer to it each May than we were in November. And also see us moving ...
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How much information can you obtain from a pulsar-black hole system?

Imagine that we have detected an interesting source in the sky that we believe is generated by a pulsar orbiting a black hole. The challenge here is the following: What physically relevant ...
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Time dilation of pulsar period in GR

Suppose I have a pulsar at some radius $r_p$ from a black hole and an observer at a radius $r_o$ where $r_o \gg r_p$. Assume that both the pulsar and observer are stationary. The pulsar 'pulses' at $...
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How is angular momentum stored in the superfluid component of pulsars?

I am trying to understand current theories about why pulsars glitch. I have come across two explanations that I'm assuming are complementary, but which I am having trouble reconciling. The inner ...
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How can I determine if A 34 meter antenna can be used as PTA?

What are the general requirements for any antenna, e.g., one with 34 m of dish, to be used as PTA (Pulsar Timing Array) monitoring? What are the main formulae to be used? How can the TOA (time of ...
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Why are pulsar's radiation beams collimated?

Every picture of a pulsar I see shows a very collimated radiation beam. What is the mechanism generating such a collimation? Note: I am not talking about "relativistic jets". I am talking about ...
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How can the angle to a pulsar be determined by measuring its redshift?

Suppose we (a spacecraft, probe, or similar) know our location only to within a few billion km (a few Tm) in any direction in 3D space, and we want to determine our location to a higher degree of ...
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Pulsar-white dwarf binary

In the paper from Hulse & Taylor 1975 on the first discovery of a pulsar in a binary system, they conclude that the companion to the pulsar must be a compact object, probably a neutron star or ...
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Why do we assert Hulse–Taylor binary system's orbital decay to gravitational waves and not radiation?

From this link The Hulse–Taylor system's orbit has decayed since the binary system was initially discovered, in precise agreement with the loss of energy due to gravitational waves. The ratio ...
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1 answer
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Direction of Gamma Ray Bursts

After a black hole consumes a star, why do gamma ray bursts only shoot out perpendicular to the spinning accretion disk? Why do they not shoot out parallel to the disk?
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Speed of light violation?

While reading this article Discovery of the companions of millisecond pulsars, it mentions a pulsar rotating multiple times a second, and I was wondering if this doesn't exceed the speed of light?
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Do the magnetic moments of neutrons mutually align to produce the magnetic field and emission beams of a pulsar and/or magnetar?

In this graphic of a pulsar the emission beams are at the north and south poles of the neutron star's magnetic field. I've read that the Earth's magnetic field is produced by a dynamo effect, whereby ...
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Do neutron stars emit stellar flares?

Since stellar flares are formed from the magnetic energy of a star, is it probable to assume that neutron stars can emit stellar flares as well? If so, how would the super fluid material of the star ...
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Crab pulsar radiation

Regarding the radiation from the Crab pulsar and nebula, some reading leads me to the following conclusions. The rotation energy of the neutron star is the source of the non-thermal electromagnetic ...
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Pulsar age determination

In one method to determine the age of a pulsar one assumes the spinning frequency $\nu$ to obey $\nu=-k\cdot\dot{\nu}^n$ where $k$ is some constant and $n$ is the braking index of the pulsar. For the ...
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Can you use pulsar observations to determine absolute time? How long can you go without anything else?

In this old answer of Steve Allen's, he quotes this nice passage Imagine for a moment what would happen if, just as a practical joke, someone found a way to stop all atomic clocks, just for a short ...
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Why are non-relativistic methods used in binary pulsar systems (gravitational waves)?

Although gravitational waves are a subject of the General Relativity, why do most books use Newtonian equations of motion for power radiated and rate of change of eccentricity calculations? In most ...
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Do Pulsar Stars produce sound?

Can I hear electromagnetic radiation coming from a pulsar star? Or can I hear it if I stand outside it?
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Magnetic Pole Emission from Pulsars

I've been reading up on some pulsar emission theory (admittedly written in the 70's and 80's, but I figured that's a good place to start), namely this review by Curtis Michel as well as the book Black ...
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Regarding binary systems (with pulsars)

Are binary systems (in case of stars and other celestial bodies) more favorable than independent existence? I've been going through an article regarding pulsars, where it was stated that 'many pulsars ...
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