DA 193 | |
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![]() The blazar DA 193. | |
Observation data (J2000.0 epoch) | |
Constellation | Auriga |
Right ascension | 05h 55m 30.805s |
Declination | +39° 48′ 49.165″ |
Redshift | 2.365000 |
Heliocentric radial velocity | 709,009 km/s |
Distance | 10.545 Gly |
Apparent magnitude (V) | 18.3 |
Characteristics | |
Type | Blazar |
Other designations | |
SWIFT J0555.5+3946, WMAP 100, TXS 0552+398, 2XMM J055530.7+394848 |
DA 193 is a blazar [1] located in the constellation of Auriga. It has a high redshift of 2.365. [2] [3] It was first discovered as an unknown astronomical radio source in 1971 by D.G. MacDonell and A.H. Bridle. [4] This is a low polarized quasar [5] containing a classic homogeneous synchrotron self-absorption spectrum. [6] The radio spectrum of this source shows a turnover frequency at 5 GHz [5] and this object has also been referred to as a gigahertz-peak spectrum source. [7] [8]
DA 193 is found variable on the electromagnetic spectrum. It is bright in X-rays and displays a flat X-ray spectrum that is above 10 keV. During the first week of January 2018, it underwent a giga-electron volt (GeV) flare which was detected by Fermi-LAT. [9] This GeV flare exhibited from DA 193 showed an exceeded binned gamma ray flux (1 x 10−6 ph cm−2 s−1) and was found to be extremely luminous (Lγ = (1.3 ± 0.4) x 1050 erg s−1). When observing its hard gamma-ray spectrum, the flare in DA 193 was confirmed to be a rare sight. In the optical-X-ray energy range, it shows an insignificant flux meaning its source went back to its quiescence state. [10]
DA 193 contains one of the most compact radio sources known on both millisecond and arcsecond scales. [2] In its radio structure, there are four components in the core region with the suggestion of a weak component located 2.3 mas. There is presence of a short jet extending towards the western direction. [11] Furthermore, DA 193 has a simple core-halo structure according to VLBI Observations, with the major axis of the halo having a 110° position angle. This halo's position angle is found alike to the linear polarization position angle. [5]
The central supermassive black hole of DA 193 is estimated to be (5.5 ± 0.9) x 109 Mʘ based on calculations of a single optical spectroscopic emission line information, derived from usage of C IV emission lines and acquiring empirical relations proposed by Yue Shen. Its accretion disk luminosity is estimated as (1.3 ± 0.1) x 1047 erg s−1. [10]
DA 193 has one close companion 2.9" to the north. The companion is found connected to the quasar via tidal interactions. Both objects are situated in a dense compact galaxy group. [8] [12]