Markarian 478 also known asMRK 478, is aSeyfert 1 galaxy[2] located in the constellation ofBoötes. The redshift of the galaxy is (z) 0.079,[1] giving it a distance of about 1 billion light-years from Earth. It was first discovered in 1974 by astronomers fromArecibo Observatory via a 1000-foot radiotelescope.[3] It displays doubly ionizedironemission lines in its spectrum and is classified as a radio-quietquasar.[4][5]
Markarian 478 is specifically described as a prototype narrow-line Seyfert galaxy. It displays emission lines that are increasing influx levels in blue wing components with increasing line peaks invelocity shifts. The spectrum of this galaxy also shows the presence ofabsorption lines on the blue wing components of emission doublets andLymanβ lines. Observations also found the high-ionization emission lines have high velocities at blueshifts suggesting outflowing gas is mainly produced in itsbroad-line region.[6]
The host of Markarian 478 is a roundspiral galaxy with two undisturbed asymmetric and visiblespiral arms.[5][7] Its nucleus is elongated northeast to southeast, with its main body also being elongated perpendicular to it. Evidence also showed there are faint shells or arms in the host implying a clear disturbed morphology.[8][9] A 3.3-ɥm PAH emission feature was detected in the galaxy.[10]
Markarian 478 is variable. Based on its EUV (ExtremeUltraviolet Emission)light curve, most of the flux variations occurred in the lines and not in continuum. Theamplitude variations are described as highly significant, occurring on a factor of three on a timescale less than one day.[11]
TheX-ray spectrum of Markarian 478 is soft and steep.[12] It is also mainly dominated by soft excess with some traces of excess residuals in the 5-7KeV band.[13] Based on observation results using data from Swift,XMM-Newton andAstroSat, it is shown to have both long-term and intermediate-term variability. Evidence also showed thereflection fraction is anticorrelated, with thespectral index and flux suggesting the variability was caused by hard X-rays that were producing a corona moving closer and away from its centralblack hole.[14] The mass of the black hole in Markarian 478 is estimated to be 7.30 Mʘ.[15]
^Kawakatu, Nozomu; Imanishi, Masatoshi; Nagao, Tohru (June 2007). "Anticorrelation between the Mass of a Supermassive Black Hole and the Mass Accretion Rate in Type 1 Ultraluminous Infrared Galaxies and Nearby QSOs".The Astrophysical Journal.661 (2):660–671.arXiv:astro-ph/0702552.Bibcode:2007ApJ...661..660K.doi:10.1086/516563.ISSN0004-637X.
