Questions tagged [pulsars]
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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 } \...
2
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1answer
42 views
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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7 views
Induced compton scattering
What is induced Compton scattering? I came across this term while studying pulsars. I read a few articles but could not understand. Can someone elucidate this phenomenon? Also, relevant references ...
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3answers
40 views
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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1answer
32 views
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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1answer
23 views
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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9 views
What is dispersion measure (DM)?
I’m an undergraduate physics student working on a project, part of which involves studying “dispersion measure” (as used in study of pulsars, etc). I think I understand it, but I’m not sure. What is ...
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25 views
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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15 views
Determining the dispersive delay from a pulsar
The following graph is given:
In the solutions they assume that the pulse period is 0.5 seconds. Furthermore they determine the despersive delay by:
We see that from the highest to the lowest ...
3
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2answers
59 views
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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1answer
40 views
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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24 views
What is the relationship between average pulsar amplitude and the frequency?
Hi my question is pretty much in the title when im referring to frequency im referring to the frequency of the pulses. I have plotted a graph frequency vs average pulse amplitude but i don't ...
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44 views
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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4answers
196 views
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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1answer
53 views
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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25 views
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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1answer
262 views
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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2answers
136 views
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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3answers
488 views
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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1answer
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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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60 views
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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0answers
42 views
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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126 views
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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1answer
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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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1answer
492 views
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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4answers
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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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2answers
271 views
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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3answers
155 views
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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1answer
146 views
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 $...
3
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1answer
139 views
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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0answers
20 views
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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3answers
435 views
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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1answer
148 views
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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1answer
71 views
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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1answer
255 views
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 ...
2
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1answer
113 views
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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2answers
368 views
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 ...
7
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1answer
288 views
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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1answer
347 views
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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1answer
976 views
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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1answer
261 views
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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3answers
318 views
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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506 views
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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2answers
147 views
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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1answer
254 views
Pulsar beam radiant intensity distribution
I'm curious about the radiant intensity distribution of pulsars: what's the general dependence of intensity on angle, and what are typical angular beam widths? How much does the beam width vary ...
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Where to find information on the pulsar map written to Voyager's golden record?
Where might I find details about the pulsar map written on the Voyager's golden record?
This diagram defines the location of our Sun utilizing 14
pulsars of known directions from our sun. The ...
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2answers
490 views
What causes millisecond pulsars to speed up?
Millisecond pulsars are supposed to be old neutron stars. However, they are spinning even more rapidly than newly formed pulsars. Since pulsars slow down as they age, something must have caused ...
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230 views
Ability to detect pulsars
Am I correct it remembering that unless a pulsars beams plane faces earth we can not detect them. And that similarly inbetween the pulses we can't see them either?
If so how does this differ from ...
