Question

what are quasars and pulsars. explain in detail

Answer 1

A blazar is a very compact quasar (quasi-stellar radio source) associated with a presumed supermassive black hole at the center of an active, giant elliptical galaxy. Blazars are among the most energetic phenomena in the universe and are an important topic in extragalactic astronomy.[1]

Blazars are members of a larger group of active galaxies that host active galactic nuclei (AGN). A few rare objects may be "intermediate blazars" that appear to have a mixture of properties from both optically violent variable (OVV) quasars and BL Lac objects. The name "blazar" was originally coined in 1978 by astronomer Edward Spiegel to denote the combination of these two classes.

Blazars emit a relativistic jet that is pointing in the general direction of the Earth.[2] The jet's path corresponds with our line of sight, which accounts for the rapid variability and compact features of both types of blazars. Many blazars have apparent superluminal features within the first few parsecs of their jets, probably due to relativistic shock fronts.[3] A quasar  (also quasi-stellar object or QSO) is an active galactic nucleus of very high luminosity. A quasar consists of a supermassive black hole surrounded by an orbiting accretion disk of gas. As gas in the accretion disk falls toward the black hole, energy is released in the form of electromagnetic radiation. Quasars emit energy across the electromagnetic spectrum and can be observed at radio, infrared, visible, ultraviolet, and X-ray wavelengths. The most powerful quasars have luminosities exceeding 1041 W, thousands of times greater than the luminosity of a large galaxy such as the Milky Way.[2]

The term "quasar" originated as a contraction of "quasi-stellar radio source", because quasars were first identified as sources of radio-wave emission, and in photographic images at visible wavelengths they resembled point-like stars. High-resolution images of quasars, particularly from the Hubble Space Telescope, have demonstrated that quasars occur in the centers of galaxies, and that some quasar host galaxies are strongly interacting or merging galaxies.[3]

Quasars are found over a very broad range of distances (corresponding to redshifts ranging from z < 0.1 for the nearest quasars to z > 7 for the most distant known quasars), and quasar discovery surveys have demonstrated that quasar activity was more common in the distant past. The peak epoch of quasar activity in the Universe corresponds to redshifts around 2, or approximately 10 billion years ago.[4] As of 2017, the most distant known quasar is ULAS J1342+0928 at redshift z=7.54; light observed from this quasar was emitted when the Universe was only 690 million years old. The supermassive black hole in this quasar is the most distant black hole identified to date, and is estimated to have a mass that is 800 million times the mass of our Sun.[5][6][7]



The generally accepted picture is that OVV quasars are intrinsically powerful radio galaxies while BL Lac objects are intrinsically weak radio galaxies. In both cases the host galaxies are giant ellipticals.

Alternative models, for example, gravitational lensing, may account for a few observations of some blazars which are not consistent with the general properties.

Answer 2

A quasar is a form of galactic nuclei found at very large astronomical distances away from Earth, because of this they are theorized to have played a part in the earlier universe. They are several thousand times more luminous than the Milky Way and are a supermassive black hole (SMBH) surrounded by a large accretion disk which orbits the SBMH.

A pulsar is a type of neuton star, which rotates with incredibly fast speeds, taking several milliseconds to a few seconds to complete one full revolution.They are highly magnetized and emit beams of EM radiation at opposite ends. They get their name as their light appears to pulsate, because they can only be visible if a beam point towards Earth.The pulsar has two axis, a rotational axis and a magnetic axis. Thr magnetic axis is where the beams are emitted from, while the pulsar rotates around the rotational axis.

hope it helps...