Fermi's Gamma-ray Pulsars (2009 July 9)

Vivian · Post by **Vivian** » Thu Jul 09, 2009 9:56 am

I have a question about the cosmic microwave backgroud radiation... I once heard that the red means the light run out of the space with lossing less energy, so there is less matter. On the contrary, the blue means there is more matter. Is it right? Or it is just a mistake?

orin stepanek · Post by **orin stepanek** » Thu Jul 09, 2009 12:41 pm

here's link http://apod.nasa.gov/apod/ap090709.html

Orin

bystander · Post by **bystander** » Thu Jul 09, 2009 12:45 pm

I think you are referring to the WMAP image of the CMB. Blue represents the coldest (less energy) regions and red the warmest (most energy). Today's APOD, Fermi's Gamma-ray Pulsars, is much the same, with dark blue as the lowest energy and yellow as the highest energy.

: Five Year Microwave Sky Image
Credit: NASA/WMAP Science Team; 080997_5yrFullSky_WMAP_240.jpg (23.64 KiB) Viewed 3273 times

http://map.gsfc.nasa.gov/news/index.html#microwavesky wrote:The cosmic microwave temperature fluctuations from the 5-year WMAP data seen over the full sky. The average temperature is 2.725 Kelvin (degrees above absolute zero; equivalent to -270 C or -455 F), and the colors represent the tiny temperature fluctuations, as in a weather map. Red regions are warmer and blue regions are colder by about 0.0002 degrees.

neufer · Post by **neufer** » Thu Jul 09, 2009 2:03 pm

Are radio pulsars simply difficult to detect within the Milky Way?

And if so, is it because:

1) The pulsar radio signal is lost in all the other Milky Way radio noise?
2) The pulsar radio signal is time smeared by turbulent variations in the Milky Way plasma?

http://apod.nasa.gov/apod/ap090709.html wrote:
Explanation: Born in supernovae, pulsars are spinning neutron stars, collapsed stellar cores left from the death explosions of massive stars. Traditionally identified and studied by observing their regular radio pulsations, two dozen pulsars have now been detected at extreme gamma-ray energies by the Fermi Gamma-ray Space Telescope. The detections include 16 pulsars identified by their pulsed gamma-ray emission alone.

This gamma-ray all-sky map, aligned with the plane of our Milky Way Galaxy, shows the pulsar positions, with the 16 new Fermi pulsars circled in yellow (8 previously known radio pulsars are in magenta). Bizarre stellar corpses, the Vela, Crab, and Geminga pulsars on the right are the brightest ones in the gamma-ray sky. Pulsars Taz, Eel, and Rabbit are named for the nebulae they are now known to power.

bystander · Post by **bystander** » Thu Jul 09, 2009 2:08 pm

Ok, that's Taz and Rabbit (or wabbit), where's the Eel?

brett_w7 · Post by **brett_w7** » Thu Jul 09, 2009 5:34 pm

I vote APOD for Top-Ten Website in our Universe!!!

neufer · Post by **neufer** » Thu Jul 09, 2009 5:39 pm

bystander wrote:Ok, that's Taz and Rabbit (or wabbit), where's the Eel?

http://www.youtube.com/watch?v=w7CclVneVpw

neufer · Post by **neufer** » Thu Jul 09, 2009 5:52 pm

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http://antwrp.gsfc.nasa.gov/apod/ap081021.html wrote:
Explanation: Where's the pulsar? Previously, the nebula CTA 1 showed an expanding supernova remnant, a jet, and a point source expected to be a pulsar -- a rotating neutron star producing pulses at radio energies. But no radio pulses were detected. Now NASA's recently deployed Fermi Space Telescope has solved the mystery with some of its initial observations indicating that the point source is pulsing at gamma-ray energies. The strange source is the first of a class that might be dubbed "dark pulsars", rotating neutron stars that appear to pulse only in high-energy radiations. Such pulsars might not be detectable in radio or visible light if they emit those radiations into a narrow beam not seen from Earth. If true, our Galaxy might have more pulsars left for Fermi to discover. Studying the gamma-ray properties of pulsars gives valuable clues to physics of the emission regions on neutron stars.

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Frenchy · Post by **Frenchy** » Thu Jul 09, 2009 6:25 pm

For Neufer,

What effect does radio silent space have on pulsar radio waves?

Does this differ than radio noise from the Milky Way?

The Code · Post by **The Code** » Thu Jul 09, 2009 6:29 pm

Who said space was radio silent ?

Loco · Post by **Loco** » Thu Jul 09, 2009 7:45 pm

This apod reminds me of this http://technology.sympatico.msn.cbc.ca/ ... &date=True

neufer · Post by **neufer** » Thu Jul 09, 2009 8:03 pm

Frenchy wrote:For Neufer,

What effect does radio silent space have on pulsar radio waves?

Does this differ than radio noise from the Milky Way?

A plasma (or even a neutral dielectric) will effect the time delay of a radio signal.

Plasma variations could produce various time delays of a radio signal.

Frenchy · Post by **Frenchy** » Fri Jul 10, 2009 12:23 am

Thank you Neufer...

Somebody please correct me if I'm wrong, but I think that parts of space can be radio silent, not all of space in general...

Chris Peterson · Post by **Chris Peterson** » Fri Jul 10, 2009 2:06 am

Frenchy wrote:Somebody please correct me if I'm wrong, but I think that parts of space can be radio silent, not all of space in general...

If you have any matter at all, and it is warmer than absolute zero, it will radiate EM, including radio energy. I don't think there's any place in the Universe that there isn't some matter. Of course, in deep intergalactic space the particle density may drop below one per cubic meter, and the temperature of those particles won't be much different from that of the cosmic background, but that's still going to produce some signal.

The problem, however, is how you would even see one of these very quiet zones, since behind everything is the CMB, radiating at 160 GHz. To see if some region was quiet, you would need to put a huge shield behind it, cooled to a fraction of a Kelvin. Not too practical.

Platypus · Post by **Platypus** » Fri Jul 10, 2009 6:25 am

A neutron walks into a bar and orders a drink. When the neutron gets his drink, he asks, "Bartender, how much do I owe you?" The bartender replies, "For you, neutron, no charge."

neufer · Post by **neufer** » Fri Jul 10, 2009 8:03 am

Chris Peterson wrote:
Frenchy wrote:Somebody please correct me if I'm wrong, but I think that parts of space can be radio silent, not all of space in general...
If you have any matter at all, and it is warmer than absolute zero, it will radiate EM, including radio energy. I don't think there's any place in the Universe that there isn't some matter. Of course, in deep intergalactic space the particle density may drop below one per cubic meter, and the temperature of those particles won't be much different from that of the cosmic background, but that's still going to produce some signal.

The problem, however, is how you would even see one of these very quiet zones, since behind everything is the CMB, radiating at 160 GHz. To see if some region was quiet, you would need to put a huge shield behind it, cooled to a fraction of a Kelvin. Not too practical.

Actually, this is sort of a specialty of mine since I spent a number of years doing radiative transfer calculations for NOAA in the infrared and microwave.

Both deep intergalactic space and galactic space are transparent (i.e., radio silent) at frequencies around 160 GHz for otherwise we couldn't observe the detailed structure of cosmic background radiation. Instead we would observe these gases radiating at their own temperature [possibly the average CMB temperature in which they are bathed... but bathed from all directions].

A condensed piece of matter (e.g., a cosmic dust grain) will absorb and radiate EM radiation whose wavelengths are comparable to (or smaller than) that piece of matter. However, individual molecules of neutral gas will only absorb and radiate long radio waves at certain isolated resonant frequencies. Fortunately for us, few of those gas resonant frequencies are near the ~160 GHz of the cosmic background radiation thus allowing us to easily see right through the Milky Way and other galaxies at these frequencies.

The main gaseous ingredient of space is neutral (atomic) hydrogen which is radio silent except at a number of narrow isolated resonant frequencies... particularly 1420.40575177 MHz. The dean of astronomy at University of Maryland when I was there had been instrumental in mapping the doppler shifted 1420.40575177 MHz radiation line of the Milky Way to map it's 3D structure back in the 1950's.

Chris Peterson · Post by **Chris Peterson** » Fri Jul 10, 2009 2:30 pm

neufer wrote:Actually, this is sort of a specialty of mine since I spent a number of years doing radiative transfer calculations for NOAA in the infrared and microwave.

Good point about the size of the particles. Nevertheless, space is full of particles that are both black body radiators and also radiators at discrete wavelengths. I don't think you could call any meaningful volume of space "radio silent" except in the practical sense that it is so quiet that we can treat it as transparent. Or similarly, that it radiates at an intensity far below the sensitivity of our receivers. Also from a practical viewpoint, we don't have the means to actually probe a small enough region of space to be particle free. When we look at the CMB, we are certainly seeing radiation produced in the intervening space as well. It is simply at a very low level compared with the background.

I'm also very familiar with the 1.4 GHz neutral hydrogen line (which I wouldn't call radio silent), in my case because the son of Giuseppe Cocconi is a good friend of mine since college (that being the Cocconi of the Cocconi-Morrison Conjecture).

bystander · Post by **bystander** » Mon Jul 13, 2009 12:44 pm

HEAPOW: 2009 July 13 - Blind Pulsars

neufer · Post by **neufer** » Mon Jul 13, 2009 2:02 pm

http://heasarc.gsfc.nasa.gov/docs/objects/heapow/archive/compact_objects/fermi_pulsars.html wrote: When a massive star dies, it often leaves behind a tin [sic],

<<"Back where I come from, there are men who do nothing all day but good deeds. They are called phila-, er, er, philanth-er, yes, er, good-deed doers, and their hearts are no bigger than yours. But they have one thing you haven't got - a testimonial." The Tin Woodsman is then presented with a testimonial: a clock award - a large red, heart-shaped watch made of metal that hangs from the end of a golden chain.

A loudly-ticking clock is in the center of the heart.>>

kovil · Post by **kovil** » Thu Jul 16, 2009 9:24 pm

As abstract of my interpretation of what’s happening at these Fermi Map Gamma Ray Pulsar locations:

Namely, the reasons why the Fermi gamma ray detector satellite is detecting intense gamma ray sources within our galaxy at point sources thought to be remnants of supernoved stars, and which are now gamma ray pulsars. Mainstream has it all wrong; they are not neutron stars as remnants in these structures causing pulsars (no such thing exists in reality), Yea verily, they are an electrical binary star 'relaxation-oscillator' pulsar which is actually the supernova remnant, and its electric currents are causing an inverse Compton effect amongst the matter and energy spectrum that manifests itself into a gamma ray radiation due to the situation in these locations vis-à-vis the way matter and the EM spectrum state of energy radiations interact. It translates into a gamma ray level of radiation intensity of short wavelengths due to an inverse Compton effect spiking up the level of electron intensity interaction with the plasma and creating a ‘pair production’ situation that also results in gamma ray spectrum production.
Our task is to mathematically describe how this is occurring !

Here are some supporting quotes from a Wikipedia page or two:

“Gamma rays (denoted as γ) are electromagnetic radiation of high energy. They are produced by sub-atomic particle interactions, such as electron-positron annihilation, neutral pion decay, radioactive decay, fusion, fission or inverse Compton scattering in astrophysical processes. Gamma rays typically have frequencies above 1019 Hz and therefore energies above 100 keV and wavelength less than 10 picometers, often smaller than an atom. Gamma radioactive decay photons commonly have energies of a few hundred KeV, and are almost always less than 10 MeV in energy.”

Lets’s look at ‘inverse Compton scattering’ as the mechanism for generating the Fermi Map’s Gamma Ray Pulsars energy signature.

“In physics, Compton scattering or the Compton effect is the decrease in energy (increase in wavelength) of an X-ray or gamma ray photon, when it interacts with matter. Because of the change in photon energy, it is an inelastic scattering process. Inverse Compton scattering also exists, where the photon gains energy (decreasing in wavelength) upon interaction with matter. The amount the wavelength changes by is called the Compton shift.”

[“Although nuclear compton scattering exists[1], Compton scattering usually refers to the interaction involving only the electrons of an atom. The Compton effect was observed by Arthur Holly Compton in 1923 and further verified by his graduate student Y. H. Woo in the years following. Arthur Compton earned the 1927 Nobel Prize in Physics for the discovery.”]

http://en.wikipedia.org/wiki/Compton_scattering

“The Compton effect is important because it demonstrates that light cannot be explained purely as a wave phenomenon. Thomson scattering, the classical theory of an electromagnetic wave scattered by charged particles, cannot explain low intensity shift in wavelength (Classically, light of sufficient intensity for the electric field to accelerate a charged particle to a relativistic speed will cause radiation-pressure recoil and an associated Doppler shift of the scattered light, but the effect would become arbitrarily small at sufficiently low light intensities regardless of wavelength.). Light must behave as if it consists of particles in order to explain the low-intensity Compton scattering. Compton's experiment convinced physicists that light can behave as a stream of particle-like objects (quanta) whose energy is proportional to the frequency.

“The interaction between electrons and high energy photons (~keV) results in the electron being given part of the energy (making it recoil), and a photon containing the remaining energy being emitted in a different direction from the original, so that the overall momentum of the system is conserved. If the photon still has enough energy left, the process may be repeated. In this scenario, the electron is treated as free or loosely bound. Experimental verification of momentum conservation in individual Compton scattering processes by Bothe and Geiger as well as by Compton and Simon has been important in disproving the BKS theory. If the photon is of lower energy, but still has sufficient energy (in general a few eV, right around the energy of visible light), it can eject an electron from its host atom entirely (a process known as the photoelectric effect), instead of undergoing Compton scattering. Higher energy photons (~MeV) may be able to bombard the nucleus and cause an electron and a positron to be formed, a process called pair production.”

“In a potential gradient, the k-vector of a short-wavelength wave must vary from point to point, to keep the total energy constant. Sheets perpendicular to the k-vector are the wavefronts, and they gradually change direction, because the wavelength is not everywhere the same. A wavepacket follows the shifting wavefronts with the classical velocity, with the acceleration equal to the force divided by the mass.”

The presence of intense magnetic fields surrounding relaxation oscillators which change to the beat of the polarity reversals may provide the 'pump' that 'pushes' pair-production.

“ . . . lower energy photons produced from this spectrum are scattered to higher energies by relativistic electrons in the surrounding corona.”

As there are no 'pertetual motion machines or phenomena', pulsars slowly slow down over time, as their prodigious energy is radiated away, as gamma rays in these cases.
I sure applaude mainstream science for sending up these data gathering satellites !!!
Tho I may disagree with how their data is interpreted.

Chris Peterson · Post by **Chris Peterson** » Thu Jul 16, 2009 9:37 pm

kovil wrote:Namely, the reasons why the Fermi gamma ray detector satellite is detecting intense gamma ray sources within our galaxy at point sources thought to be remnants of supernoved stars, and which are now gamma ray pulsars. Mainstream has it all wrong; they are not neutron stars as remnants in these structures causing pulsars (no such thing exists in reality), Yea verily, they are an electrical binary star 'relaxation-oscillator' pulsar which is actually the supernova remnant, and its electric currents are causing an inverse Compton effect amongst the matter and energy spectrum that manifests itself into a gamma ray radiation due to the situation in these locations vis-à-vis the way matter and the EM spectrum state of energy radiations interact. It translates into a gamma ray level of radiation intensity of short wavelengths due to an inverse Compton effect spiking up the level of electron intensity interaction with the plasma and creating a ‘pair production’ situation that also results in gamma ray spectrum production.
Our task is to mathematically describe how this is occurring !

The burden is on those who have problems with mainstream thinking (it is mainstream for a reason!) to demonstrate why their own ideas are better. You make no effort to do so here, and you make no effort to "mathematically describe how this is occurring"- something that should be done before the "theory" is even advanced.

Starship Asterisk*