A gravitational lens is matter, such as a cluster of galaxies or a point particle, that bends light from a distant source as it travels toward an observer. The amount of gravitational lensing is described by Albert Einstein's general theory of relativity with much greater accuracy than Newtonian physics, which treats light as corpuscles travelling at the speed of light.
Lynx is a constellation named after the animal, usually observed in the Northern Celestial Hemisphere. The constellation was introduced in the late 17th century by Johannes Hevelius. It is a faint constellation, with its brightest stars forming a zigzag line. The orange giant Alpha Lyncis is the brightest star in the constellation, and the semiregular variable star Y Lyncis is a target for amateur astronomers. Six star systems have been found to contain planets. Those of 6 Lyncis and HD 75898 were discovered by the Doppler method; those of XO-2, XO-4, XO-5 and WASP-13 were observed as they passed in front of the host star.
Abell 2218 is a large cluster of galaxies over 2 billion light-years away in the constellation Draco.
Abell 1835 IR1916 was a candidate for being the most distant galaxy ever observed, although that claim has not been verified by additional observations. It was claimed to lie behind the galaxy cluster Abell 1835, in the Virgo constellation.
Gravitational microlensing is an astronomical phenomenon caused by the gravitational lens effect. It can be used to detect objects that range from the mass of a planet to the mass of a star, regardless of the light they emit. Typically, astronomers can only detect bright objects that emit much light (stars) or large objects that block background light. These objects make up only a minor portion of the mass of a galaxy. Microlensing allows the study of objects that emit little or no light.
In astronomy, the intracluster medium (ICM) is the superheated plasma that permeates a galaxy cluster. The gas consists mainly of ionized hydrogen and helium and accounts for most of the baryonic material in galaxy clusters. The ICM is heated to temperatures on the order of 10 to 100 megakelvins, emitting strong X-ray radiation.
The Bullet Cluster consists of two colliding clusters of galaxies. Strictly speaking, the name Bullet Cluster refers to the smaller subcluster, moving away from the larger one. It is at a comoving radial distance of 1.141 Gpc.
The Comet Galaxy, a spiral galaxy located 3.2 billion light-years from Earth, in the galaxy cluster Abell 2667, was found with the Hubble Space Telescope. This galaxy has slightly more mass than our Milky Way. It was detected on 2 March 2007.
The cluster CL0024+17 is a cluster of galaxies located in Pisces, and about 4 billion light years distant.
Abell 520 is a galaxy cluster in the Orion constellation, located at a co-moving radial distance of 811 Mpc (2,645 Mly) and subtends 25 arcminutes on the Earth sky.
While the presence of any mass bends the path of light passing near it, this effect rarely produces the giant arcs and multiple images associated with strong gravitational lensing. Most lines of sight in the universe are thoroughly in the weak lensing regime, in which the deflection is impossible to detect in a single background source. However, even in these cases, the presence of the foreground mass can be detected, by way of a systematic alignment of background sources around the lensing mass. Weak gravitational lensing is thus an intrinsically statistical measurement, but it provides a way to measure the masses of astronomical objects without requiring assumptions about their composition or dynamical state.
The Cloverleaf quasar is a bright, gravitationally lensed quasar.
Abell 2152 is a bimodal galaxy cluster and one of three clusters comprising the Hercules Supercluster. It contains 3 BCGs; the S0 lenticular UGC 10204, the pair UGC 10187, and the SA0 unbarred lenticular CGCG 108-083. In total there are 41 galaxies which are confirmed to be members of the cluster. The cluster is classified as a Bautz-Morgan type III and Rood-Sastry class F cluster, indicating morphological irregularity and perhaps dynamical youth. It is receding from the Milky Way galaxy with a velocity of 12385 km/s.
Georges Meylan is a Swiss astronomer, born on July 31, 1950, in Lausanne, Switzerland. He was the director of the Laboratory of Astrophysics of the Swiss Federal Institute of Technology (EPFL) in Lausanne, Switzerland, and now a professor emeritus of astrophysics and cosmology at EPFL. He is still active in both research and teaching.
NGC 3893 is a spiral galaxy located in the constellation Ursa Major. It is located at a distance of circa 50 million light years from Earth, which, given its apparent dimensions, means that NGC 3893 is about 70,000 light years across. It was discovered by William Herschel on February 9, 1788. NGC 3893 interacts with its satellite, NGC 3896.
MS 0302+17 is a galaxy supercluster located in the constellation Aries at a distance of 4.485 billion light years, equivalent to a comoving distance of 5.338 billion light years. The dimensions are around 6 million parsecs.
Godzilla is a variable star in the Sunburst galaxy at redshift z = 2.37, observed through the gravitational lens PSZ1 G311.65-18.48. It was originally identified in the NW arc as a possible transient event in images taken with the Hubble Space Telescope (HST).
