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Fast radio bursts (FRBs) are millisecond-duration radio transients.sup.1,2 of unknown origin. Two possible mechanisms that could generate extremely coherent emission from FRBs invoke neutron star magnetospheres.sup.3-5 or relativistic shocks far from the central energy source.sup.6-8. Detailed polarization observations may help us to understand the emission mechanism. However, the available FRB polarization data have been perplexing, because they show a host of polarimetric properties, including either a constant polarization angle during each burst for some repeaters.sup.9,10 or variable polarization angles in some other apparently one-off events.sup.11,12. Here we report observations of 15 bursts from FRB 180301 and find various polarization angle swings in seven of them. The diversity of the polarization angle features of these bursts is consistent with a magnetospheric origin of the radio emission, and disfavours the radiation models invoking relativistic shocks. Polarization observations of the fast radio burst FRB 180301 with the FAST radio telescope show diverse polarization angle swings, consistent with a magnetospheric origin of the emission., Author(s): R. Luo [sup.1] [sup.2] [sup.3] , B. J. Wang [sup.1] [sup.2] , Y. P. Men [sup.1] [sup.2] , C. F. Zhang [sup.1] [sup.2] , J. C. Jiang [sup.1] [sup.2] [...]

Quasars have long been known to be variable sources at all wavelengths. Their optical variability is stochastic and can be due to a variety of physical mechanisms; it is also well-described statistically in terms of a damped random walk model (1). The recent availability of large collections of astronomical time series of flux measurements (light curves (2-5)) offers new data sets for a systematic exploration of quasar variability. Here we report the detection of a strong, smooth periodic signal in the optical variability of the quasar PG 1302-102 with a mean observed period of 1,884 ± 88 days. It was identified in a search for periodic variability in a data set of light curves for 247,000 known, spectroscopically confirmed quasars with a temporal baseline of about 9 years. Although the interpretation of this phenomenon is still uncertain, the most plausible mechanisms involve a binary system of two supermassive black holes with a subparsec separation. Such systems are an expected consequence of galaxy mergers and can provide important constraints on models of galaxy formation and evolution., Subparsec supermassive black-hole (SMBH) binary systems are not resolvable except possibly with long baseline radio interferometry. An alternative approach to their detection is through a modulated variability--caused by, for example, [...]

Author(s): Rychard Bouwens (corresponding author) [1] Quasars are the brightest non-transient emitters of light in the Universe. These remarkable objects have been discovered to exist as early as 750 million [...]

For decades, physicists have pursued direct evidence of black holes. In 2011, Russia launched Spektr-R, or RadioAstron, a space radio telescope, to collect the confirmational data. Yuri Kovalev, a physicist [...]

The intergalactic medium was not completely reionized until approximately a billion years after the Big Bang, as revealed (1) by observations of quasars with redshifts of less than 6.5. It has been difficult to probe to higher redshifts, however, because quasars have historically been identified (2-4) in optical surveys, which are insensitive to sources at redshifts exceeding 6.5. Here we report observations of a quasar (ULAS J112001.48 + 064124.3) at a redshift of 7.085, which is 0.77 billion years after the Big Bang. ULAS J1120 + 0641 has a luminosity of 6.3 x [10.sup.13] [L.sub.[dot encircle]] and hosts a black hole with a mass of 2 x [10.sup.9] [M.sub.[dot encircle]] (where [L.sub.[dot encircle]] and [M.sub.[dot encircle]] are the luminosity and mass of the Sun). The measured radius of the ionized near zone around ULAS J1120 + 0641 is 1.9 megaparsecs, a factor of three smaller than is typical for quasars at redshifts between 6.0 and 6.4. The near-zone transmission profile is consistent with a Lyα damping wing (5), suggesting that the neutral fraction of the intergalactic medium in front of ULAS J1120 + 0641 exceeded 0.1., ULAS J1120 + 0641 was first identified in the United Kingdom Infrared Telescope (UKIRT) Infrared Deep Sky Survey (6) (UKIDSS) Eighth Data Release, which took place on 3 September 2010. [...]

The exquisite angular resolution of the Chandra x-ray telescope has enabled the detection and study of resolved x-ray jets in a wide variety of astronomical systems. Chandra has detected extended jets in our galaxy from protostars, symbiotic binaries, neutron star pulsars, black hole binaries, extragalactic jets in radio sources, and quasars. The x-ray data play an essential role in deducing the emission mechanism of the jets, in revealing the interaction of jets with the intergalactic or intracluster media, and in studying the energy generation budget of black holes. black holes | quasars | radio sources doi/ 10.1073/pnas.0913890107

The most distant quasars known, at redshifts z ≅ 6, generally have properties indistinguishable from those of lower-redshift quasars in the rest-frame ultraviolet/optical and X-ray bands (1-3). This puzzling result suggests that these distant quasars are evolved objects even though the Universe was only seven per cent of its current age at these redshifts. Recently one z ≅ 6 quasar was shown not to have any detectable emission from hot dust (4), but it was unclear whether that indicated different hot-dust properties at high redshift or if it is simply an outlier. Here we report the discovery of a second quasar without hot-dust emission in a sample of 21 z ≅ 6 quasars. Such apparently hot-dust-free quasars have no counterparts at low redshift. Moreover, we demonstrate that the hot-dust abundance in the 21 quasars builds up in tandem with the growth of the central black hole, whereas at low redshift it is almost independent of the black hole mass. Thus z ≅ 6 quasars are indeed at an early evolutionary stage, with rapid mass accretion and dust formation. The two hot-dust-free quasars are likely to be first-generation quasars born in dust-free environments and are too young to have formed a detectable amount of hot dust around them., More than 40 quasars have been discovered at redshifts z ≅ 6 (refs 5, 6); at this epoch, the Universe was less than one billion years old. They harbour black [...]

Microquasars are accreting black holes or neutron stars in binary systems with associated relativistic jets. Despite their frequent outburst activity, they have never been unambiguously detected emitting high-energy gamma rays. The Fermi Large Area Telescope (LAT) has detected a variable high-energy source coinciding with the position of the x-ray binary and microquasar Cygnus X-3. Its identification with Cygnus X-3 is secured by the detection of its orbital period in gamma rays, as well as the correlation of the LAT flux with radio emission from the relativistic jets of Cygnus X-3. The gamma-ray emission probably originates from within the binary system, opening new areas in which to study the formation of relativistic jets. 18 September 2009; accepted 5 November 2009 Published online 26 November 2009; 10.1126/science.1182174

Byline: J. Nakajima (1), Y. Koyama (2), M. Sekido (2), N. Kurihara (2), T. Kondo (2), M. Kimura (3), N. Kawaguchi (4) Keywords: fringe detection; high sensitivity; quasar; VLBI Abstract: We report on the detection of VLBI fringes from quasars by a new VLBI system operating at 1 Gbps (1024 Mbits-per-second). Newly developed 1024 Msps (mega sample-per-second) AD samplers and 1024 Mbps recorders were used for the observations. A correlator with external buffers was used for the 1024 Mbps correlation processing of the tapes data.Our new VLBI system enabled 1024 Mbps VLBI, and this allowed the sampling of a 512 MHz bandwidth from a radio telescope receiver. This is the highest sampling speed ever used for VLBI, and the widest bandwidth used for VLBI observation. Initial sensitivity as evaluated by SNR comparison with earlier VLBI systems produced results to matched the expanded bandwidth. In our first observations, simultaneous optical fibre linked real-time VLBI observations were made to check the validity of data and precisely detemine the clock offsets among the radio telescopes. Author Affiliation: (1) Communications Research Laboratory, Kashima Space Research Center, 893 Hirai, Kashima-city Ibaraki, 314-0012, Japan (2) Communications Research Laboratory, Kashima Space Research Center, 893 Hirai, Kashima-city Ibaraki, 314-0012, Japan (3) Department of Astronomy, University of Tokyo, Tokyo, 113-003, Japan (4) National Astronomical Observatory Osawa Mitaka, Tokyo, 181-8588, Japan Article History: Registration Date: 12/10/2004

The first 50 years at Palomar, 1949-1999, and the early years of cosmology, stellar evolution, and high-energy astrophysics are discussed from a historical perspective, covering two observational programs set up for the 200-in Palomar telescope by Walter Baade and Edwin Hubble. New discoveries and developments not foreseen in 1950 have changed the programs over time, and in the future they will proceed with changed goals. Spectacular new understanding and great accomplishments characterize the results of the planning of astronomers in the 1930s.