The extent to which the cool, dense gas at the centers of massive galaxy clusters can be disrupted remains an outstanding question in astrophysics. Although physical processes such as mergers and central galaxy activity have been shown to suppress cooling and therefore star formation in the central gas, the cool core has almost always been observed to remain more or less intact. Recently, however, a team of KIPAC researchers has found the most extreme example yet of these processes disrupting the core.
The Fermi LAT has observed, for the first time, gamma-rays produced in cosmic-ray interactions in several neighboring galaxies - and is even able to spatially resolve one of those galaxies. This has given us a unique global view of cosmic ray acceleration, that previous Milky Way studies could not provide.
Gamma-ray emission from the LMC
May 5, 2015 | Understanding Dark Energy Through CMB Observations
A KIPAC astrophysicist has published some of the first constraints on dark energy and other cosmological parameters using the measured signal from "shadows" of galaxy clusters in the CMB.
The Atacama Cosmology Telescope (ACT), located in the Atacama desert in Chile.
May 5, 2015 | Fermi Space Telescope Sees the Andromeda Galaxy
For the first time, thanks to the Fermi Space Telescope, high energy gamma rays gave been detected coming from another spiral galaxy much like our own Milky Way. It is now evident that the differences in gamma-ray luminosity among galaxies show that the density of cosmic rays varies and is correlated with the formation of new stars.
May 5, 2015 | A Cosmic Bullet Shoots Extra X-rays
Galaxy clusters are a well known source of X-rays. KIPAC researchers have shown that at least one cluster, the famous 'Bullet' Cluster, has an extra component of X-ray emission detectable beyond the dominant one seen ubiquitously elsewhere.
May 5, 2015 | Cosmic Archaeology With the Leader of a Group
A team of astronomers, including two from KIPAC, have created a map of X-ray emission from around the central galaxy of a galaxy group. Along with data from other wavelengths, it dramatically shows the effects of outbursts from the central active galactic nucleus that occurred millions of years ago.
Among the successes of the Fermi Gamma-ray Space Telescope is its discovery of the gamma-ray emission from many pulsars, the fascinating beacons in space. Additionally, KIPAC scientists have also used what Fermi has not seen from some pulsars to learn more about them.
May 5, 2015 | Telltale Modulation In Gamma Rays Implies Orbit
Data from the Fermi Gamma-ray Space Telescope has revealed a new gamma-ray binary, a rare class of object in which a gamma ray source is in orbit around a star.
Artist's conception of an X-ray binary in which a star and a black hole are in orbit around each other. The black hole pulls mass off the star, which interacts in the extreme conditions surrounding the black hole.
May 5, 2015 | Life In the Dark Matter Fast Lane
A new prediction of the density and velocity distribution of dark matter particles at our position in the Galaxy has provided a revised estimate of the likely detection rates for dark matter in particle physics experiments.
Typical conception of the halo of dark matter surrounding the Galaxy.
May 5, 2015 | Let the Sun Shine (In Gamma Rays) II
Unifying the astronomically near and far, the Fermi Gamma-ray Space Telescope has seen its first signature of cosmic rays interacting with the light from our Sun.
The left panel shows the LAT gamma rays per pixel from near the Sun and the right panel shows the same for another patch of sky. There is a clear large flux from the solar disk and a less dense but extended flux surrounding it.
Photometric redshift determination is crucial to the success of dark energy missions such as LSST and DES. A KIPAC postdoc has developed an important tool for photometric redshift estimation and applied it to 60 million galaxies from the Sloan Digital Sky Survey.
Six randomly chosen galaxies' photometric redshift probability distributions from Cunha and colleagues' SDSS galaxy sample.
May 5, 2015 | Learning About Dark Matter From Invisible Satellites
Simulations suggest that our Milky Way galaxy has many dark-matter-dominated satellites swarming around it, but without large numbers of stars they are too dim to be seen as satellite galaxies. However, KIPAC astrophysicists using data from the Fermi Gamma-ray Space Telescope can learn about dark matter by fishing for these dark satellites with gamma rays.