[Europan Ocean (OP)]

Since we know there are pulsars, why is it we do not see flashing stars? Interesting to hear pulsars on my old radio in 1988.

[Janus]

The "brightest" pulsar is some 1000 ly away, has an apparent magnitude of 23.6. under ideal viewing conditions, the best the unaided human eye could see would be about a magnitude 6.  It also pulses at a rate of ~ 11 pulses per sec, which is close to the limit of what we could even detect as a being a flicker.

The closest known pulsar is some 500 ly away, and pulses approximately every 6 milliseconds, much faster than we could see.
One factor also in play is that the peak frequency of the electromagnetic radiation emitted by these pulsars lies outside of the visible spectrum.

[evan_au]

It is possible to visualise pulsars flashing by putting a rotating disk (with holes in it) in the optical path of a telescope.

This produces a stroboscopic effect: When the pulsar flash coincides with a hole, it goes through, but when it coincides with the solid disk, it doesn't.

By adjusting the rotation speed of the disk, you can get the pulsar to flash at a rate which can be perceived by the human eye.

Or you can use a high-speed camera on a large telescope, and just slow it down:

[Hayseed]

Is there a phase change with time?  I have doubts about a rotating disk structure, it would cause a phase change of the signal.  If the spectrum is much higher than light, then it's direct particle emission, which means fast dynamic power.

Perhaps some interaction between the poles.   Cutting a large amount of M flux could certainly do it.

Very mysterious.  Could life survive in a galaxy with one?  Are the ones we know of in galaxies?

[syhprum]

Life seems to be surviving OK in our galaxy (for the moment) despite several  nearby ones.

[Hayseed]

I did not know that, how many have been found here?

[evan_au]

Could life survive in a galaxy with [a pulsar]?  Are the ones we know of in galaxies?

The Crab Nebula pulsar in the video above is in our galaxy, at a distance of about 6,500 light years.

This pulsar is the remains of a supernova explosion that was observed in 1054.
See: https://en.wikipedia.org/wiki/Crab_Nebula

The neutron star itself is not very dangerous if you are on a nearby star - but the supernova explosion would have destroyed Earth-like life around nearby stars out to perhaps 30 light-years.
See: https://en.wikipedia.org/wiki/Near-Earth_supernova#Risk_by_supernova_type

Is there a phase change with time? 

Pulsars are very precise clocks, with very regular ticks.

There are some exceptions:
- Some pulsars are in orbit around another star. This means it ticks faster when it is approaching us, and more slowly when it is moving away. But it is still very accurate when measured over a complete orbit.
- Sometimes there are sudden slowdown & speedup in the pulses - it resumes the original timing after a few seconds. Some physicists interpret this as coming from sloshing of the superfluid quark soup in the interior.
- Sometimes there are permanent changes in the pulse rate. Astrophysicists interpret this as "starquakes" - the cooling neutron star shrivels, forcing up immense mountain chains against the phenomenal gravity. Eventually these mountain chains (perhaps millimeters high) collapse, falling back into a smooth ellipsoid. This changes the rotation rate measurably (if you use an atomic clock).

So the timing of the pulsar rotation is much more accurate than the rotation rate of a cardboard disk - but in this case, the goal is to observe the flashing with the naked eye, so extreme precision is not needed in the rotating disk.
See: https://en.wikipedia.org/wiki/Pulsar#Precise_clocks

If the spectrum is much higher than light, then it's direct particle emission,

An astronomical telescope observed pulsars at X-Ray wavelengths.
See: https://asd.gsfc.nasa.gov/blueshift/index.php/2017/08/03/rxtes-greatest-pulsar-hits/

By the way, X-Rays are much higher frequency than light, and they do behave like particles, but they also behave like waves - as demonstrated by X-Ray diffraction crystallography (which gave the original hints about the structure of DNA).

[Janus]

Is there a phase change with time?  I have doubts about a rotating disk structure, it would cause a phase change of the signal.  If the spectrum is much higher than light, then it's direct particle emission, which means fast dynamic power.

Perhaps some interaction between the poles.   Cutting a large amount of M flux could certainly do it.

Very mysterious.  Could life survive in a galaxy with one?  Are the ones we know of in galaxies?

The disk evan_au is referring to a a device for viewing a pulsar, not anything doing with the structure of the pulsar.
The pulsar itself is a rotating neutron star with a strong magnetic field.  The magnetic poles and rotational axis are not aligned ( just like for the Earth).  The high spin rate and magnetic field combine to funnel particles into beams emitted from the magnetic poles.  The beams are constant but sweep like a search light.  If you are in the path of the beam your will see it "flash" as it sweeps by.  (This means that there could be more pulsars out there that we no nothing about as their beams never sweep past the Earth.
There are a few classes of Pulsar. 
Rotational pulsars tap the rotational energy of the star to drive the beam and slowly decrease their spin and flash rate over time*
Accretion pulsars have a binary companion that has reached the stage where it has begun to expand. The pulsar starts to gather in material from the companion, and it is the gravitational potential of this material that provides the energy for the beam.
Magnetars have extremely strong magnetic fields and it is the collapse of the field that provides the energy.

*The fact the pulsars are only noticeable from point through which their beams sweep and the rate decays over time is the reason The Voyager probes included "pulsar maps"   Which showed what pulsars we had detected from the Earth, their relative distances and pulse rates.  The idea being that if some alien civilization discovered them in in the far, far future, they would be able to work out not only from where the probes were launched, but also when, as there would have only been one place at one time where that particular pattern would have been seen.

[evan_au]

Are the [pulsars] we know of in galaxies?

There have been searches for pulsars in other galaxies, but they aren't easy to find.
- Over 20 have been found in the Magellenic Clouds: dwarf galaxies that are orbiting our galaxy, so they are quite close
- One potential pulsar has been found in Andromeda Galaxy: Similar in size to our galaxy, it is also fairly close, heading for a collision with our galaxy in around 5 billion years
- A few have been found in farther galaxies by the Nustar X-Ray satellite

It is easier to search for them using radio telescopes, as some of the energy is in radio waves. In fact, the first detection of a pulsar by Jocelyn Bell was with a radiotelescope.

So while a supernova can briefly outshine a whole galaxy, pulsars are very small (perhaps 30km across) and not very luminous.
See: http://www.pulsarastronomy.net/IAUS291/download/Posters/IAUS291_KondratievV_207.pdf
https://www.nasa.gov/feature/jpl/nustar-helps-find-universes-brightest-pulsars