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.
May 5, 2015 | Nomadic Planets May Swarm the Galaxy
Much public attention has focused on the recent discoveries of many hundreds of planets around other stars. A group of KIPAC scientists has now estimated that there may be up to ten thousand times as many planet-sized objects flying freely through our Galaxy as there are planets orbiting stars. They explore the implications for future sky surveys such as LSST, as well as our view of planet formation and even the origin of life.
May 5, 2015 | Shapes of Galaxies on the Brain
KIPAC astrophysicists have used a technique that processes information in a way analogous to the human brain in order to determine whether galaxy shapes can help determine their place in the Universe.
The effect of adding multiple parameters representing galaxy shape information on the photo-z accuracy, as determined by Singal et al. with their neural network method.
The only way to accurately predict the conditions near black holes is with extensive computer simulations of the complicated physics involved. While black holes are the quintessential manifestation of Einstein's General Relativity, very few precision tests of the theory have been based on actual observations of black holes. New simulation results point to an observable property of such systems that could be used as a precision test of Einstein's theory.
May 5, 2015 | Fermi LAT constrains dark matter in galaxy clusters
Clusters of galaxies are the most massive structures in the universe. Most of the mass in these clusters is considered to be dark matter. The Fermi LAT monitors these clusters for a gamma-ray signal from dark matter annihilation. No such signal has been found yet, but the non-observation starts to constrain a wide range of proposed dark matter models.
May 5, 2015 | The Chunky Suburbs of Galaxy Clusters
An analysis of X-ray observations has provided the clearest picture to date of the size, mass, and matter content of a giant cluster of galaxies. The study also provides the first direct evidence that the multi-million-degree gas in the cluster's outskirts is clumped into enormous clouds.
Centaurus A (Cen A) is one of the brightest radio sources in the sky: it is a giant elliptical Galaxy about 10 million light years away, making it the closest active galaxy we know. A remarkable feature of the radio image of this galaxy is that the bright central source is accompanied by a pair of giant radio "lobes," thought to be fuelled by relativistic jets generated in the dynamical process of gas accretion around the super-massive black hole residing at the galaxy's center.
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.
Cosmic inflation may have imprinted a distinctive pattern, associated with so-called B-Modes, on the polarization pattern of the Cosmic Microwave Background radiation on degree angular scales. A team including several KIPAC researchers will be attempting to detect this key signal using the BICEP2 telescope over the next two years, following its "first light" observations of spinning dust in our galaxy this spring.
May 5, 2015 | A Gamma-ray Pulsar With a Record-breaking Magnetic Field
Fermi's Large Area Telescope has detected gamma-ray pulsations from a radio pulsar with one of the highest magnetic fields known. The object appears to be a missing link between standard pulsars and the more extreme magnetars.
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 | The Milky Way's Unusual Companions
By most accounts, the Milky Way is a fairly unexceptional galaxy in the Universe at large. However, a team of KIPAC scientists has shown that it has one very unusual feature: its two lesser companions, the Magellanic Clouds.
Images of systems from the SDSS spectroscopic catalog where Milky Way-like hosts have two Magellenic Cloud-like companions