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MOJAVE is a VLBI program which monitors a statistically complete, radio-selected sample of 135 relativistically beamed, flat-spectrum active galactic nuclei for over more than a decade. In order to understand the high-energy behavior of this radio co mplete sample, we are performing Swift fill-in observations on the complete MOJAVE-I sample since 2007. The complete study of the spectral energy distribution from radio to X-ray bands on this radio-selected sample will provide us an opportunity to understand the nature of AGN. Here we present the preliminary results of the spectral energy distributions of six gamma-quiet or faint sources from this project: NRAO 140, PKS 0403-13, PKS B0422+004, PKS 0823+033, 3C 309.1, and 3C 380.
We discuss acceleration measurements for a large sample of extragalactic radio jets from the MOJAVE program which studies the parsec-scale jet structure and kinematics of a complete, flux-density-limited sample of Active Galactic Nuclei (AGN). Accele rations are measured from the apparent motion of individual jet features or components which may represent patterns in the jet flow. We find that significant accelerations are common both parallel and perpendicular to the observed component velocities. Parallel accelerations, representing changes in apparent speed, are generally larger than perpendicular acceleration that represent changes in apparent direction. The trend for larger parallel accelerations indicates that a significant fraction of these changes in apparent speed are due to changes in intrinsic speed of the component rather than changes in direction to the line of sight. We find an overall tendency for components with increasing apparent speed to be closer to the base of their jets than components with decreasing apparent speed. This suggests a link between the observed pattern motions and the underlying flow which, in some cases, may increase in speed close to the base and decrease in speed further out; however, common hydro-dynamical processes for propagating shocks may also play a role. About half of the components show non-radial motion, or a misalignment between the components structural position angle and its velocity direction, and these misalignments generally better align the component motion with the downstream emission. Perpendicular accelerations are closely linked with non-radial motion. When observed together, perpendicular accelerations are usually in the correct direction to have caused the observed misalignment.
In its first three months of operations, the Fermi Gamma-Ray Observatory has detected approximately one quarter of the radio-flux-limited MOJAVE sample of bright flat-spectrum active galactic nuclei (AGNs) at energies above 100 MeV. We have investiga ted the apparent parsec-scale jet speeds of 26 MOJAVE AGNs measured by the Very Long Baseline Array (VLBA) that are in the LAT bright AGN sample (LBAS). We find that the gamma-ray bright quasars have faster jets on average than the non-LBAS quasars, with a median of 15 c, and values ranging up to 34 c. The LBAS AGNs in which the LAT has detected significant gamma-ray flux variability generally have faster jets than the nonvariable ones. These findings are in overall agreement with earlier results based on nonuniform EGRET data which suggested that gamma-ray bright AGNs have preferentially higher Doppler boosting factors than other blazar jets. However, the relatively low LAT detection rates for the full MOJAVE sample (24%) and previously known MOJAVE EGRET-detected blazars (43%) imply that Doppler boosting is not the sole factor that determines whether a particular AGN is bright at gamma-ray energies. The slower apparent jet speeds of LBAS BL Lac objects and their higher overall LAT detection rate as compared to quasars suggest that the former are being detected by Fermi because of their higher intrinsic (unbeamed) gamma-ray to radio luminosity ratios.
The radio loud galaxy NGC 1052 is being studied in an intensive multi-band campaign including X-ray brigthness monitoring and spectroscopic observations, single-dish radio brightness monitoring at centimetre wavelengths, and a high-frequency very-lon g-baseline interferometry monitoring program. Here we present a progress report on our studies from this program. The final goal of our observations is to relate the findings from the high-resolution radio images with the observed variations in the X-ray regime, to address the accretion processes and their relationship with the radio jet activity.
We have studied the inner regions of the LINER galaxy NGC1052 since the mid 1990s at high resolution with 15 GHz very-long-baseline interferometry observations. A compact, two-sided jet structure is revealed, with multiple sub-parsec scale features m oving outward from the central region with typical speeds of 0.26 c. Complementary to this, since early 2005 we are performing a multi-mission campaign of observations of this source, including X-ray spectroscopy, X-ray, and radio flux density monitoring, and VLBA observations at 22 GHz and 43 GHz. X-ray variability is present at time scales of weeks, comparable with the structural changes observed by VLBI. Here we present first results of the high-resolution imaging observations and discuss these findings in the context of the multi-band campaign.
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