Fermi Space Telescope sharpens its high-energy vision

January 7, 2016 by Francis Reddy
This image, constructed from more than six years of observations by NASA's Fermi Gamma-ray Space Telescope, is the first to show how the entire sky appears at energies between 50 billion (GeV) and 2 trillion electron volts (TeV). For comparison, the energy of visible light falls between about 2 and 3 electron volts. A diffuse glow fills the sky and is brightest in the middle of the map, along the central plane of our galaxy. The famous Fermi Bubbles, first detected in 2010, appear as red extensions north and south of the galactic center and are much more pronounced at these energies. Discrete gamma-ray sources include pulsar wind nebulae and supernova remnants within our galaxy, as well as distant galaxies called blazars powered by supermassive black holes. Labels show the highest-energy sources, all located within our galaxy and emitting gamma rays exceeding 1 TeV. Credit: NASA/DOE/Fermi LAT Collaboration

Major improvements to methods used to process observations from NASA's Fermi Gamma-ray Space Telescope have yielded an expanded, higher-quality set of data that allows astronomers to produce the most detailed census of the sky yet made at extreme energies. A new sky map reveals hundreds of these sources, including 12 that produce gamma rays with energies exceeding a trillion times the energy of visible light. The survey also discovered four dozen new sources that remain undetected at any other wavelength.

"What made this advance possible was a complete reanalysis, which we call Pass 8, of all data acquired by Fermi's Large Area Telescope (LAT)," said Marco Ajello, a Fermi team member at Clemson University in South Carolina. "The end result is effectively a complete instrument upgrade without our ever having to leave the ground."

By carefully reexamining every gamma-ray and particle detection by the LAT since Fermi's 2008 launch, scientists improved their knowledge of the detector's response to each event and to the background environment in which it was measured. This enabled the Fermi team to find many that previously had been missed while simultaneously improving the LAT's ability to determine the directions of incoming gamma rays. These improvements effectively sharpen the LAT's view while also significantly widening its useful energy range.

Using 61,000 Pass 8 gamma rays collected over 80 months, Ajello and his colleagues constructed a map of the entire sky at energies ranging from 50 billion (GeV) to 2 trillion electron volts (TeV). For comparison, the energy of visible light ranges from about 2 to 3 electron volts.

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Watch Fermi scientists explain why they're so excited about Pass 8, a complete reprocessing of all data collected by the mission's Large Area Telescope. This analysis increased the LAT's sensitivity, widened its energy range, and effectively sharpened its view through improved backtracking of incoming gamma rays. Credit: NASA's Goddard Space Flight Center

"Of the 360 sources we cataloged, about 75 percent are blazars, which are distant galaxies sporting jets powered by supermassive black holes," said co-investigator Alberto Domínguez at the Complutense University in Madrid. "The highest-energy sources, all located in our galaxy, are mostly remnants of supernova explosions and pulsar wind nebulae, places where rapidly rotating neutron stars accelerate particles to near the speed of light." One famous example, the Crab Nebula, tops the list of the highest-energy Fermi sources, producing a steady drizzle of gamma rays exceeding 1 TeV.

Astronomers think these very are produced when lower-energy light collides with accelerated particles. This results in a small energy loss for the particle and a big gain for the light, transforming it into a gamma ray.

For the first time, Fermi data now extend to energies previously seen only by ground-based detectors. Because ground-based telescopes have much smaller fields of view than the LAT, which scans the whole sky every three hours, they have detected only about a quarter of the objects in the catalog. This study provides ground facilities with more than 280 new targets for follow-up observations.

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Tour the best view of the high-energy gamma-ray sky yet seen. This video highlights the plane of our galaxy and identifies objects producing gamma rays with energies greater than 1 TeV. Credit: NASA's Goddard Space Flight Center

"An exciting aspect of this catalog is that we find many new sources that emit gamma rays over a comparatively large patch of the sky," explained Jamie Cohen, a University of Maryland graduate student working with the Fermi team at NASA's Goddard Space Flight Center in Greenbelt. "Finding more of these objects enables us to probe their structures as well as better understand mechanisms that accelerate the subatomic particles that ultimately produce gamma-ray emission." The new catalog identifies 25 of these extended objects, including three new pulsar wind nebulae and two new supernova remnants.

Ajello presented the findings Thursday at the 227th meeting of the American Astronomical Society in Kissimmee, Florida. A paper describing the catalog has been accepted for publication in The Astrophysical Journal Supplement.

NASA's Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership, developed in collaboration with the U.S. Department of Energy and with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the United States.

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Gamma-ray emission from the highest-energy sources detected by Fermi is likely produced by what scientists call the inverse Compton process. When an electron moving near the speed of light strikes a low-energy photon, the collision slightly slows the electron and boosts the light's energy into the gamma-ray regime. Credit: NASA's Goddard Space Flight Center

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Mike_Massen
1.6 / 5 (10) Jan 08, 2016
Just saw this UK dramatization again recently, interesting to review in relation to the oddball claims of few people here (GR &SR) relativity's wrong or even faked (FFS) & that back then in those times when the first evidence arose perception was the viewable galaxy was the only one & with a lot less stars that we now accept
http://www.imdb.c...=nv_sr_1

No-one is perfect as a few claim of Einstein re his personal life but, that doesn't diminish the integrity of his focus on the Physics & Maths and at a most chaotic time in Europe, so to those that continue to snipe at the efforts people take to pursue Science, should get a grip and man up with Science instead...

Change of pace with light relief re Einstein from totally different angle & Meg Ryan
http://www.imdb.c...=nv_sr_2

For those keenly interested in the Math detail this is essential !
https://www.youtu...PKAKZWx8

Bit hard but, easily based on Gauss :-)
bschott
2.3 / 5 (9) Jan 08, 2016
those that continue to snipe at the efforts people take to pursue Science, should get a grip


You are entitled to your opinion. You forget that popular opinion doesn't make math constructs real and that people with a different understanding will interpret this information differently.

It isn't your fault that you cannot grasp the reasons why we dispute what you call science. Watching your reaction to having it explained and reading your response posts says all we need to know about how receptive you are to alternate theories.

When supporters of GR and the standard model try to dance around the holes in it by constantly referring to it's successes at certain predictions it clearly differentiates the thinkers from the drones.

interesting to review in relation to the oddball claims of few people here


You support a model that is missing 80% of the matter required for it to work and predicts infinite self compression of matter....oddball claims indeed!
Mike_Massen
1.8 / 5 (10) Jan 08, 2016
bschott says
You forget that popular opinion doesn't make math constructs real ... will interpret this information differently
Vague
1 Maths describes, doesn't (attempt to) explain
2 Evidence paramount

Not referring to popular (uneducated) opinion. If referring to GR/SR you appear unaware of immense cohesion of foundational math/physics leading & confirms, to high level of certainty at local scales:-; GPS (4-6), Mercury (planet) orbit, Hg (element) MP, NIST atomic clocks, Hafele-Keating etc

bschott claims
It isn't your fault that you cannot grasp the reasons why we dispute what you call science
Beg Pardon, then clarify ?
https://en.wikipe.../Science
What aspect of that "popular" description you dispute & if any, then clarify re less popular hard nosed (maths based) references ?

ie Clarify your vague hand-wave tangential comments, as cannot be counted sensible attempts to articulate a position

Have you formally studied Calculus to proficiency ?
Mike_Massen
1.8 / 5 (10) Jan 08, 2016
continued @bschott
claims
Watching your reaction to having it explained..
Where/when have you EVER had it explained as there's; Nil math, Nil experimental method, Nil cohesive intersection of Math/Physics, Nil "rounding" to ladder fundamentals into a substantive position !

bschott claims
When supporters of GR and the standard model try to dance around the holes in it by constantly referring to it's successes at certain predictions it clearly differentiates the thinkers from the drones
You Fail to apply key tests cognisant of "Balance of Probabilities" in conjunction with proven asymptotic nature of empirical nature of Physics to date

Its as if you Never learned; Limits, Differentiation/Integration have you ?

bschott claims
You support a model that is missing 80% of the matter required for it to work and predicts infinite self compression of matter....oddball claims indeed!
No. You MISS key point, Dark Matter (DM) is a mere algebraic place holder !
Mike_Massen
1.8 / 5 (10) Jan 08, 2016
continued @bschott,
Asked you direct questions before but, you sidestep them or hand-wave & don't address them with anything connected either with evidence in conjunction with aspect of convergence re "Balance of Probabilities" *or* rely on unclear assumptions you're unable to articulate *or* pursuing vague un-scientific agenda either because you seek to; obfuscate *or* aren't aware, not educated in Calculus, you're malleable to emotionally attached positions the universe *should* be simpler than advanced maths describes

This is easy to clarify in useful stages but, unlike mere offhand writings, it does require a certain application of intellect & associated discipline, I trust you appreciate the Scientific method as generally described:-
https://en.wikipe...c_method

Step 1
Do you accept in yes/no fashion; Newton's gravitation, as described by Newton, was sufficient to describe the solar system planetary orbits reasonably well at that time ?
bschott
2.3 / 5 (9) Jan 08, 2016
Thank you for behaving exactly as described.

What aspect of that "popular" description you dispute & if any


DUH



You support a model that is missing 80% of the matter required for it to work and predicts infinite self compression of matter....oddball claims indeed!


read much?

, then clarify re less popular hard nosed (maths based) references ?


I do not need a math based reference to state that matter cannot self compress to a state that physics cannot describe.

You MISS key point, Dark Matter (DM) is a mere algebraic place holder !


That is precisely all it is and ever will be. A variable in a math equation that describes no aspect of reality what soever. The efforts to prove that it is real are rooted in math based claims made people like you.

Such a waste of time and resources.

Where/when have you EVER had it explained as there's; Nil math,


It is not necessary to use math when discussing fundamental claims.

bschott
2.3 / 5 (9) Jan 08, 2016
Step 1
Do you accept in yes/no fashion; Newton's gravitation, as described by Newton, was sufficient to describe the solar system planetary orbits reasonably well at that time?


I used to. Unfortunately, the theory that orbital velocity stabilizes orbital path against the constant "pull" of gravity has been proven incorrect at large scales. The requirement for your algebraic placeholder on the order of magnitude that it is required made it abundantly clear that orbital motion cannot be dictated by mass and velocity alone.

Mike I was going to go on, but I must leave. Enjoy your math and good luck with it.
Mike_Massen
1.4 / 5 (10) Jan 08, 2016
@bschott
Ah a key breakthrough re understanding common origin of such belief, as I see you refused to answer question re Calculus. Please read about it, as it is *essential* to predictably launch rockets, design buildings, encode algorithms in control systems etc etc, tah :-)

Evidence shows your position based on phrase rather than a foundationally connected tenable position re math/physics

ie You state "I do not need a math based reference to state that matter cannot self compress to a state that physics cannot describe.", raises questions

1. Have you arrived at this position or been told it is somehow "self-evident" ?
2. If former than what process did you develop ?
3. If latter then did they tell you a rationalization connected with any Evidence ?

Lets see if you can follow an earlier & more direct line of reasoning to maybe take convergent steps to explore why you repeat a claim not define or articulated ?

Step 0.1
Do U accept a force stops you lifting off ?
Mike_Massen
1.4 / 5 (10) Jan 08, 2016
bschott says
I used to
Lets not be trivial about this, its important so don't cross threads, take it patiently & with attention to detail. Please focus & re-read my question in conjunction with "Balance of Probabilities" at time of Newton

bschott claims
Unfortunately, the theory that orbital velocity stabilizes orbital path against the constant "pull" of gravity has been proven incorrect at large scales
Sorry, incomplete, you jump ahead of yourself & damage cognition of asymptotic nature of Scientific process & helpful if you consider Scientific method, have you read the link please ?

bschott says
The requirement for your algebraic placeholder on the order of magnitude that it is required made it abundantly clear that orbital motion cannot be dictated by mass and velocity alone
Please focus, to skip steps in cognition disables your understanding of just WHY the current view has immense value, as key to critical faculty

R u genuine ? more later...
Bigbangcon
2.7 / 5 (7) Jan 08, 2016
"Astronomers think these very high-energy gamma rays are produced when lower-energy light collides with accelerated particles. This results in a small energy loss for the particle and a big gain for the light, transforming it into a gamma ray."
"Gamma-ray emission from the highest-energy sources detected by Fermi is likely produced by what scientists call the inverse Compton process".

All these are spurious, shame-faced and lame explanations made to conform with official cosmology. What about the gamma ray bursts (GRBs)?
The only way gamma rays are produced are, when patches (that includes small particles, clouds, stars, cluster of stars etc.) of chance accumulated matter and antimatter (mainly at the core of the galaxies) encounter each other and undergo annihilation reaction.
But then of course no Big Bang! You have to accept a dialectical view of the universe: http://redshift.v...MAL.pdf.
jonesdave
2.6 / 5 (10) Jan 08, 2016
@BBC,
From the introduction in the paper you linked:
"A halo of gamma-rays originating in and surrounding the Milky Way....."

Very interesting, I'm sure, but nobody believes these GRBs occur in the milky way! Their redshifts show them to be extremely distant. Around 1000 have been observed, none of them thought to originate in our galaxy.
So I think I'll take that paper with a pinch of salt.

http://www.eso.or...nn15085/
http://www.eso.or...2/grond/
Bigbangcon
4 / 5 (4) Jan 08, 2016
@ jonesdave:
You got it wrong, unfortunately. This paper does not claim that all the GRBs; (even one) comes from the Milky Way. It mainly explains the diffuse gamma ray of the Milky Way and speculates that it should be common in other galaxies as well and even in the dust of intergalactic space, due to spontaneous appearance (disappearance) of both matter and antimatter from the quantum vacuum.

It clearly says (with references), "Gamma ray bursts are short (~10 ms to ~100s) random flashes of gamma rays at cosmological distances". Please read the paper more carefully. There are relatively more recent articles and books by the same author on the cosmic gamma ray sources and a dialectical approach to cosmology in general.
Among other things the source of gamma ray (implying antimatter) and of an infinite and eternal universe, are the major "black holes" in the foundation of the virtual edifice of modern official cosmology and are the strong points of dialectical cosmology.
antialias_physorg
5 / 5 (2) Jan 11, 2016
Gotta love the const correctness of their code (see image displayed on first video in the article)
Mike_Massen
1 / 5 (5) Jan 24, 2016
bschott, reminder you have not yet answered my questions directed at you ?

To clarify an earlier one, you said "you can't believe matter self compresses", I asked you to clarify & iirc you mentioned a cloud of Hydrogen gas shouldn't be able to draw itself together by gravitation to develop enough gravitation to start a fusion reaction etc Is that correct ?

If so then you would be wise to get a primer in Calculus & appreciate the cloud of gas, even at low temperatures has motion & as it has come together has momentum too, can you appreciate that and that it is sufficient as a trigger re further motion ?

Did you do Calculus at high school as that would help a lot in getting to grips with Physics ?

In respect of that its only a small step from Calculus to understand Gauss' theorems as that appears to be the key basis for Einstein's field equations, can you appreciate that ?
https://en.wikipe...ss's_law
&
https://en.wikipe..._theorem

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