Astronomers have discovered the brightest gravitationally lensed object ever seen. They don’t expect to find many quasars brighter than that in the whole observable universe. The quasar is fueled by a supermassive black hole at the heart of a young galaxy in the process of forming. An immense amount of energy is emitted as the black hole consumes material around it.
The quasar would have gone undetected if not for the power of gravitational lensing, which boosted its brightness by a factor of 50.
Very distant quasars are identified by their red color (due to absorption by diffuse gas in intergalactic space), sometimes their light is “contaminated,” and looks bluer because of the starlight of an intervening galaxy. As a result, they may be overlooked in quasar searches because their color is diluted to resemble that of a normal galaxy. Fan proposes that many other remote quasars have been missed due to this light contamination.
This detection provides clues for how to find more ‘phantom quasars’. We now know more about how to look for them with the confidence that they exist.
A theoretical study predicts that we are missing a large number ‘phantom quasars.’ If the quasars are more numerous then it would revolutionize our idea of what happened right after the Big Bang.
Strong gravitational lensing provides a powerful probe of the physical properties of quasars and their host galaxies. A high fraction of the most luminous high-redshift quasars was predicted to be lensed due to magnification bias. However, no multiple imaged quasar was found at z over 5 in previous surveys. We report the discovery of J043947.08+163415.7, a strongly lensed quasar at z = 6.51, the first such object detected at the epoch of reionization, and the brightest quasar yet known at z over 5. High-resolution Hubble Space Telescope imaging reveals a multiple imaged system with a maximum image separation θ ~ 0farcs2, best explained by a model of three quasar images lensed by a low-luminosity galaxy at z ~ 0.7, with a magnification factor of ~50. The existence of this source suggests that a significant population of strongly lensed, high-redshift quasars could have been missed by previous surveys, as standard color selection techniques would fail when the quasar color is contaminated by the lensing galaxy.
The discovery of the first strongly lensed (μ ≈ 50) quasar at z over 6 (J0439+1634) represents a breakthrough in our understanding of the early universe. We derive the theoretical consequences of the new discovery. We predict that the observed population of z over 6 quasars should contain many sources with magnifications μ less than or equal to 10 and with image separations below the resolution threshold. Additionally, current selection criteria could have missed a substantial population of lensed z greater than 6 quasars, due to the contamination of the drop-out photometric bands by lens galaxies. We argue that this predicted population of lensed z reater than 6 quasars would be misclassified and mixed up with low-z galaxies. We quantify the fraction of undetected quasars as a function of the slope of the bright end of the quasar luminosity function, β. For β less than or equal to 3.6, we predict that the undetected lensed quasars could reach half of the population, whereas for β greater than or equal to 4.5 the vast majority of the z greater than 6 quasar population is lensed and still undetected. This would significantly affect the z greater than 6 quasar luminosity function and inferred black hole mass distributions, with profound implications for the ultraviolet, X-ray, and infrared cosmic backgrounds and the growth of early quasars.