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An examination of long-term luminosity differences for approximately 300 quasars at redshifts between 1 and 3, whose optical magnitude is calculated alternately for 17 years, reveals a positive co-association between average luminosity and the timescale of variability. It is suggested that gravitational microlensing causes quasar variability.

Data from the new Compton Gamma Ray Observatory showed that many quasars are brighter in gamma rays than any other electromagnetic radiation and that gammaray bursters peculiarly spread evenly across the sky, not concentrated along the Milky Way as was predicted. The results from ita 4 gamma ray-sensitive instruments were presented and evaluated by astrophysicists and had found new areas of further study.

Research describing the ionization of intergalactic hydrogen is presented. In particular observations of the spectra of very distant quasars is investigated for reionization transitions.

Low-density intergalactic gas at high redshift is predicted to be poor in heavy elements in models for the composition of the diffuse intergalactic medium. A method to analyze carbon and oxygen absorption lines in quasar spectra is presented, enabling the probing of heavy-element abundances at a redshift of three within low density areas of intergalactic gas. The unexpected enrichment of low density gas in heavy elements in the experiment, indicates that early small galaxies could be more efficient at ejecting heavy elements that was previously thought.

A survey of radio-loud high-redshift quasars not only shows a sharp decrease in space density for redshifts greater than three but also provides a measure of the galaxy formation and interactions between galaxies. A search of a large sample of flat-spectrum Parkes radio sources from a region covering 40% of the sky reveals the near negligible influence of dust on radio emission from quasars. The high redshift quasars may be distinguished by their Lyman shift/hydrogen-based heavy obscuring in the optical B band. The results assume flat spectra for the very high redshift quasars.

Spectroscopic surveys of high-redshift objects in the fields of the Z>4 quasars has led to identification of two Lyman-alpha-emitting galaxies at redshift 4.55. These galaxies seem to be undergoing their first burst of star formation, and their study may provide the best direct estimates of star formation at the earliest epochs. The search for high-redshift objects involves their exposure through a narrow-band filter focused on the quasar's redshifted Lyman-alpha emission. Five Z>4 quasar fields have been observed, but the spectroscopic analysis is complete only for Z = 4.55 quasar.

Spectroscopic observations in the field of quasar 2233 + 131 have led to identification of a galaxy DLA 2233 + 131, which is related to a known damped Lyman-alpha absorption system. This galaxy shows no evidence of an active nucleus and its properties closely resemble those of young disk galaxies that are in the early stages of formation. The spectroscopic studies are conducted using a low resolution imaging spectrograph, and the spectra contain a prominent Lyalpha line emission. These results provide strong backing to the notion that damped Lyman-alpha systems may be young high red-shift galaxies.

The Lyman-alpha emission from a companion to the quasar at redshift z = 4.7 suggests an age related to the initial stages of formation of the universe. A large portion of the emission is due to a gaseous nebula photoionized by the quasar. The rest of the light appears to be due to quasar light scattered from dust in the companion body or emission from young stars in the nebula. The observations probably indicate the initial stages of formation of a galaxy-sized structure.

The ultraviolet spectra of the quasar pair Q0107-025A and B reveal the presence of four Lyman-alpha lines, which originate from both the objects. The lines are in the redshift range from 0.5 to 0.9 and reveal that the radius of the clouds is not less than 160 per Hubble constant kilo parsecs. The clouds have feeble internal motions consistent with the explanations provided by the conventional models of motion.

High-resolution spectrographic studies of cosmic microwave background radiation at non-zero redshifts reveals the occurrence of absorption from the first fine-structure level of neutral carbon atoms in a cloud with a redshift of 1.776 toward quasar Q1331+170. A temperature of 7.4 plus or minus 6.8 K is suggested by the population ratio in the absence of marked excitational sources. This value agrees with the theoretical value of 7.58 K.

Absorption lines in the spectra of quasar HS1700+6416, which has a redshift of z=2.72, indicate a ratio of the abundance of oxygen to that of carbon in intergalactic gas clouds that is three to five times higher than the O/C ratio found in the Solar System. The visibility of helium lines and continuum absorption in the ultraviolet spectrum indicates that the background ionizing radiation field has not been influenced by the decay of massive neutrinos. These results support the elimination of such neutrinos as a candidate for dark matter.

Astronomy researchers at the University of Texas (Austin) have found evidence suggesting that all radio-loud quasars may be blazars, and the differences between them may be related to the angle […]

The results from a long spectroscopic investigation of the high-redshift quasar Q0302-003 provide further evidence for the existence of a tenuous plasma in intergalactic space at high redshift. Radiation from quasars makes this plasma highly ionized. Q0302-003 shows a clearing, or 'void,' in the Lyman forest of narrow Lyman-alpha absorption lines from hydrogen along its line of sight. This void is not replicated in the He+ absorption, indicating that the He+ opacity is dominated by gas which is more diffuse than the Lyman-forest systems.

Hubble Space Telescopic observation of the diffuse intergalactic medium shows the presence of an absorption feature on the far ultraviolet spectrum of the high redshift quasar Q0302-003 which confirms that integalactic medium is a highly polarized plasma of hydrogen and helium. The conclusions support the Big Bang model of nucleosynthesis which suggests that the largest redshifts indicate light elements such as helium that were formed in the early Universe.

Questions concerning quasars were the focus of discussions at a meeting at the Carnegie Observatories in Pasadena, CA, in Feb 1997. According to current theory, quasars are huge black holes fueled by gaseous accretion disks, the latter containing material that becomes very hot and gleams brightly as it goes down the funnel into the black hole. Measurements of the polarization of quasar light showed that the light they emit becomes polarized if it scatters off surrounding material. The measured spectrum can be divided into polarized and unpolarized parts to offer several views of the same quasar, thus providing an indirect probe of the geometry of quasar outflows.