Some interesting figures in this paper. Status of gamma ray astronomy.

http://arxiv.org/pdf/1509.00012.pdf

eg.
Colour pics showing the gamma rays sky in galactic coordinates.

A Pie chart showing that 56% of gamma ray sources are blazars, 33% are unidentified, 6% are pulsars, 2% are interacting galaxies, and the remaining few percent include normal galaxies, AGNs, globular clusters, supernova remnants, novae, high mass binaries and pulsar winds.

Future missions. None approved. ComPair proposed, to close the sensitivity gap between X-ray (IBIS) and gamma ray (Fermi).

A blazar is a very compact quasar (quasi-stellar radio source) associated with a presumed supermassive black hole at the center of an active, giant elliptical galaxy. Blazars are among the most energetic phenomena in the universe and are an important topic in extragalactic astronomy.

https://en.wikipedia.org/wiki/Blazar

“Happy birthday to you, Fermi space telescope!”

Do you get a very large bottle of “Windex” for your birthday?

Bubblecar said:

A blazar is a very compact quasar (quasi-stellar radio source) associated with a presumed supermassive black hole at the center of an active, giant elliptical galaxy. Blazars are among the most energetic phenomena in the universe and are an important topic in extragalactic astronomy.

https://en.wikipedia.org/wiki/Blazar

Blazars come in two types: BL Lacertae objects (BL Lac) and Flat Spectrum Radio Quasars (FSRQs), with about equal numbers of each. Both have jets of relativistic matter that happen to be pointed towards the Earth. FSRQs have quasar-like emission lines in their spectrum, BL Lacs do not. The lack of emission lines and extremely wide range of luminosities makes it very difficult to determine the redshift of BL Lacs.

Wikipedia is remiss in having next to nothing on FSRQs.

I wonder if the 33% that are unidentified are something new or enough data doesn’t exist to idenfify them properly

Cymek said:

I wonder if the 33% that are unidentified are something new or enough data doesn’t exist to idenfify them properly

ditto

Cymek said:

I wonder if the 33% that are unidentified are something new or enough data doesn’t exist to identify them properly

I downloaded the Fermi data (4 years catalog) and plotted the results. To me, they were startling!

The distribution of the unidentified sources across the sky does not even remotely resemble the overall distribution of identified sources. It does, however, closely match the distribution of identified pulsars, the pulsars are only a small percentage of all identified sources.

What this means is that by far the majority of unidentified Fermi sources are sources within the Milky Way itself.

My next test was to check whether the variability of these unidentified sources matches the variability of other Fermi sources. The variability of the unknown sources is much less than that of most if not all other gamma ray sources. It is only marginally less than that of pulsars, however.

I conclude that almost all of the Fermi unknown gamma ray sources have to be compact objects within the Milky Way, and although they could be stellar-mass black holes, the lack of variability points more towards them being neutron stars. A new type of neutron star/pulsar that has no detectable radio wave or X-ray radiation.