PKS 0405--385: the smallest radio quasar?

Abstract

We have observed profound variability in the radio flux density of the quasar PKS 0405-385 on timescales of less than an hour; this is unprecedented amongst extragalactic sources. If intrinsic to the source, these variations would imply a brightness temperature 10^21 K, some nine orders of magnitude larger than the inverse Compton limit for a static synchrotron source, and still a million times greater than can be accommodated with bulk relativistic motion at a Lorentz factor equal to 10. The variability is intermittent with episodes lasting a few weeks to months. Our data can be explained most sensibly as interstellar scintillation of a source component which is < 5 microarcsec in size - a source size which implies a brightness temperature > 5 times 10^14 K, still far above the inverse Compton limit. Simply interpreted as a steady, relativistically beamed synchrotron source, this would imply a bulk Lorentz factor 1000.

13 pages, 3 PostScript figures, to appear in ApJL

Cited by in corpus (73)

• Blazars in the Fermi Era: The OVRO 40-m Telescope Monitoring Program
• Science with ASKAP - the Australian Square Kilometre Array Pathfinder
• Sub-milliarcsecond Imaging of Quasars and Active Galactic Nuclei. IV. Fine Scale Structure
• Science With The Australian Square Kilometre Array Pathfinder
• The discovery of a microarcsecond quasar: J1819+3845
• Rapid Variability and Annual Cycles in the Characteristic Time-scale of the Scintillating Source PKS 1257-326
• Interstellar scintillation as the origin of rapid radio variability in the quasar J1819+3845
• First Results from MASIV: The Micro-Arcsecond Scintillation-Induced Variability Survey
• VAST: An ASKAP Survey for Variables and Slow Transients
• Sub-Milliarcsecond Imaging of Quasars and Active Galactic Nuclei. II. Additional Sources
• On the optical and X-ray afterglows of gamma ray bursts
• Interstellar Scintillation of the Polarized Flux Density in Quasar, PKS 0405-385
• Annual modulation in the scattering of J1819+3845: peculiar plasma velocity and anisotropy
• Annual modulation in IDV of quasar 0917+624 due to Interstellar Scintillation
• The ATCA Intraday Variability Survey of Extragalactic Radio Sources
• Rapid interstellar scintillation of PKS B1257-326: two-station pattern time delays and constraints on scattering and microarcsecond source structure
• Testing the inverse-Compton catastrophe scenario in the intra-day variable blazar S5 0716+71. I. Simultaneous broadband observations during November 2003
• On the Hadronic Beam Model for Gamma-ray Production in Blazars
• A survey for transients and variables with the Murchison Widefield Array 32-tile prototype at 154 MHz
• Parsec-Scale Images of Flat-Spectrum Radio Sources in Seyfert Galaxies
• The VSOP 5 GHz Active Galactic Nucleus Survey: V. Imaging Results for the Remaining 140 sources
• Cyclotron Maser Emission from Blazar Jets?
• The Size of the Radio-Emitting Region in Low-luminosity Active Galactic Nuclei
• Interstellar Scintillation Observations of 146 Extragalactic Radio Sources
• The Spectral Variability of the GHz-Peaked Spectrum Radio Source PKS 1718-649 and a Comparison of Absorption Models
• Extreme Brightness Temperatures and Refractive Substructure in 3C273 with RadioAstron
• The IDV source J1128+5925, a new candidate for annual modulation?
• Understanding the Radio Variability of Sgr A*
• Measuring the brightness temperature distribution of extragalactic radio sources with space VLBI
• Extreme radio-wave scattering associated with hot stars
• Intraday Variability in Northern Hemisphere Radio Sources
• Long-term monitoring of Molonglo calibrators
• Quasar Jets and their Fields
• Dynamic spectral mapping of interstellar plasma lenses
• Variable 21cm absorption at z=0.3127
• High Observed Brightnesses in Radio Jets
• The Allen Telescope Array Pi GHz Sky Survey II. Daily and Monthly Monitoring for Transients and Variability in the Bootes Field
• Diffractive Interstellar Scintillation of the Quasar J1819+3845 at 21cm
• Intra-day variability observations of S5 0716+714 over 4.5 years at 4.8 GHz
• Quasi-periodic behaviour in the $\gamma$-ray light curve of the blazar PKS 0405-385
• The high brightness temperature of B0529+483 revealed by RadioAstron and implications for interstellar scattering
• Electric field representation of pulsar intensity spectra
• The intra-hour variable quasar J1819$+$3845: 13-year evolution, jet polarization structure and interstellar scattering screen properties
• Factors Determining Variability Time in Active Galactic Nucleus Jets
• A seasonal cycle and an abrupt change in the variability characteristics of the intraday variable source S4 0954+65
• Extremely Anisotropic Scintillations
• The Micro-Arcsecond Scintillation-Induced Variability (MASIV) Survey III. Optical Identifications and New Redshifts
• ASKAP observations of multiple rapid scintillators reveal a degrees-long plasma filament
• Interstellar scintillations of PSR B1919+21: space-ground interferometry
• The MASIV Survey IV: relationship between intra-day scintillation and intrinsic variability of radio AGNs
• The Microarcsecond Sky and Cosmic Turbulence
• Power-law models of totally anisotropic scattering
• Detection of Six Rapidly Scintillating AGNs and the Diminished Variability of J1819+3845
• A snowflake's chance in heaven
• Scintillation in the Circinus Galaxy water megamasers
• Photometric Monitoring of the Gravitationally Lensed Ultraluminous BAL Quasar APM08279+5255
• Scintillation as a Probe of the Intergalactic Medium
• Radio Variable and Transient Sources on Minute Timescales in the ASKAP Pilot Surveys
• The presence of interstellar scintillation in the 15 GHz interday variability of 1158 OVRO-monitored blazars
• Spica and the annual cycle of PKS B1322-110 scintillations
• Optimization of Survey Strategies for Detecting Slow Radio Transients
• Intrinsic intraday variability in the gravitational lens system B0218+357
• The jet of S5 0716+71 at $\mu$as scales with RadioAstron
• Interstellar Scintillation of an Extreme Scintillator: PKS B1144-379
• The brightness temperature problem in extreme IDV quasars: a model for PKS 0405-385
• Radio observations of the first three-month Fermi-AGN at 4.8 GHz
• BL LAC PKSB1144-379 an extreme scintillator
• Scintillation-induced Variability in Radio Absorption Spectra against Extragalactic Sources
• Scintillation kinks, bumps and wiggles in the radio spectrum of the quasar PMN J1106-3647
• Observations of Intrahour Variable Quasars: Scattering in our Galactic Neighbourhood
• Optical study of PKS B1322-110, the intra-hour variable radio source
• Tidal disruption of "snow clouds" by unassociated stars
• Why AGN Studies Need Higher Resolution