PKS 0048−097 is aBL Lacertae object located in the western region of theCetus constellation. The redshift of the object is (z) 0.635 based on measurement ofemission lines,[2] estimating it to be 6 billion light-years from Earth.[1] It was first discovered by astronomers during theParkes Observatory radio sources survey in 1966.[3] The source is known to be variable based on its flux density and is located northeast fromNGC 246, aplanetary nebula.[4][5]
PKS 0048−097 is optically violently variable. When observed duringphotometric monitoring on January 18, 2001, the source fluctuated inbrightness, increasing by 0.38magnitudes within 45 minutes then decreasing its brightness before increasing once more.[6] In addition, the object has displayed several flaring periods with a large optical outburst occurring in June 2009.[7] It was noted to be in a moderate high optical state of 15.5 magnitudes with its energy distribution estimated to be from 1014 reaching up to 2.5 x 1015 Hz.[8] Long-term variations were observed via opticalwavelengths of almost 3 magnitudes with a flickering period of 8 magnitude less than one week.[9] Anear-infrared flaring period was detected in January 2011.[10]
The radio structure of PKS 0048−097 is compact. Based on observations, the source displays aradio spectrum with a turnover frequency at 10GHz but becomes inverted to 22 GHz when its activity becomes minimum.[11] Imaging byVery Long Baseline Interferometry showed there is ajet towards the southeast direction with aposition angle of 165°, a polarized jet component and a weakly polarized radio core.[12] Extendedradio emission from the core is seen in the center of both a possible hotspot and a diffused structure.[13]Very Large Array observations found an extended secondary component holding a flux density of 0.05 ± 0.01 Jansky.[14]
PKS 0048−097 is classified as apolarization rotator. It has polarization variations occurring at thetime scale of five years, which in turn, are associated with a component described as slow varying opposed to outbursts on short time scales. The polarization position angle is also noted as stable at 90° ± 1.5° without any signs of majoramplitude changes in this eight year observation period. A rotation of 260° was reported, beginning before the outburst in 1974-75 and ending as soon the outburst reached a peak of 8 GHz. Further observations detected its spectrum elevating at allfrequencies suggesting the outburst was broadband.[15]
The host galaxy of PKS 0048−097 is undetected, but is assumed to be anelliptical galaxy.[16] It has a faint companion located 2.5 arcseconds east from its nucleus appearing as both resolved and associated together with the source based on imaging.[17]
Aquasi-periodicitymodulation was found for PKS 0048−097. Based on light curve data observations, the periodicity is estimated between 350 and 600 days. The structure is also known to vary dramatically with its jet direction shifting inposition angle from -160° south-westwards to +160° south-eastwards.[18]
^Kadler, M.; Hughes, P. A.; Ros, E.; Aller, M. F.; Aller, H. D. (2006-08-31). "A quasi-periodic modulation of the radio light curve of the blazar PKS B0048-097".Astronomy & Astrophysics.456 (2):L1–L4.arXiv:astro-ph/0605587.doi:10.1051/0004-6361:200600026.ISSN0004-6361.
