Structure of radio sources with remarkably flat spectra: PKS 0735+178

Journal Article · Sat Oct 01 04:00:00 EDT 1977 · Astron. J.; (United States)

DOI:https://doi.org/10.1086/112125· OSTI ID:7097895

Marscher, A P

We investigate three incoherent synchrotron models which can account for the remarkably flat radio spectrum (..cap alpha..=0 from 0.4 to 90 GHz) of the BL Lac object PKS 0735+178. The simplest interpretation of the spectrum of 0735+178, that it results from optically thin synchrotron emission from relativistic electrons with energy distribution N (E) proportionalE/sup -1/, is shown to be untenable: The radio spectrum in this case extends into the optical region in such a way that the predicted emission exceeds the measured optical flux densities. An alternative model, in which a single nonuniform, self-absorbed source is generated by a wind flowing from some central object, requires highly efficient in situ acceleration of relativistic electrons plus at least 10/sup 57/ ergs in invisible matter. On the other hand, if sources with flat spectra are to be explained by the presence of multiple (three or more), discrete uniform components, the results of Jones (1977) indicate that for each source the magnetic field and relativistic electron distribution must be correlated with the size of each individual component in some special way. Multifrequency VLBI observations are proposed which will allow us to determine the detailed structure (and possibly the ultimate origin) of compact radio sources.

• Research Organization: National Radio Astronomy Observatory and University of Virginia, Charlottesville, Virginia 22901
• OSTI ID: 7097895
• Journal Information: Astron. J.; (United States), Journal Name: Astron. J.; (United States) Vol. 82:10; ISSN ANJOA
• Country of Publication: United States
• Language: English

Related Subjects

640103* -- Astrophysics & Cosmology-- Quasi-Stellar
Radio
& X-Ray Sources-- (-1987)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BREMSSTRAHLUNG
COSMIC DUST
COSMIC GASES
COSMIC RADIO SOURCES
DUSTS
ELECTROMAGNETIC RADIATION
ELECTRON SPECTRA
FLUIDS
GASES
INTERSTELLAR GRAINS
MAGNETIC FIELDS
PARTICLES
PLASMA
RADIATIONS
RADIOWAVE RADIATION
SPECTRA
STELLAR WINDS
SYNCHROTRON RADIATION