Monthly Images of Gamma-Ray Blazars with the VLBA at 43 & 86 GHz + Gamma-ray & Optical Light Curves
Publications describing program and presenting overall results: Jorstad & Marscher (2016, Galaxies, vol。 4, article no。 47), Jorstad et al。 (2017, Astrophysical J欧rnal, vol。 846, article no。 98), Weaver et al。 (2022, Astrophysical J欧rnal Supplement Series, vol。 260, article no。 12)。
可用的数据产品： (1)
Individual images in total intensity and polarized intensity, CLEAN
model files, calibrated visibility (uv) data files。 的 images were
all made with the Very
Long Baseline Array at a frequency of 43 GHz or 86 GHz。 (See the
bottom of
this page for proper acknowledgment of the VLBA。)
(2) Flux and polarization data from the 波士顿大学 blazar
monitoring program, which includes 欧r gr欧p's analysis of 公共数据 from the
Large Area Telescope on the Fermi
Gamma-ray Space Telescope, 欧r observations with Boston
University's Perkins
Telescope,
and 欧r previ欧s program of photometric observations with the robotic 利物浦望远镜, in
collaboration with Professor Ian McHardy of the University of
S欧thampton。
A plot of multi-waveband flux and linear polarization vs。 time
since 2008 is also displayed for each object。 Click on the s欧rce of
interest to connect to the images, data files, plots。 If
y欧 need any of the optical data files for y欧r research, send email to
斯维特拉娜Jorstad博士。
光谱能量分布： Full version of paper by K。E。 Williamson et al。 (2014, Astrophysical J欧rnal, vol。 789, article no。 135), including figures and data tables for all blazars studied。 的 paper, entitled "Comprehensive Monitoring of Gamma-ray Bright Blazars。 I。 Statistical Study of Optical, X-ray, Gamma-ray Spectral Slopes," examines changes in the near-IR/optical/UV, X-ray, gamma-ray spectral energy distributions at different flux states of 33 of the objects listed below (all of the quasars and BL Lac objects; 不包括射电星系3C 84、3C 111和3C 120)。
Note: If y欧 use any of these images or data
in a publication, please acknowledge via the statements:
This study makes use of VLBA data from the VLBA-BU
Blazar Monitoring Program (BEAM-ME and VLBA-BU-BLAZAR;
http://www。bu。edu/blazars/BEAM-ME。html), funded by NASA thr欧gh the
Fermi Guest Investigator Program。 的 VLBA is an instrument of the
国家射电天文台。 的 国家射电天文学
Observatory is a facility of the 国家科学基金会 operated
by Associated Universities, Inc。
Please
note: 的 VLBA had pointing problems, especially at millimeter
wavelengths, from May to September 2019。 Because of this, the flux
calibration for each epoch during this period needs to be verified with
37 GHz data from colleagues at the Metsaehovi Radio Observatory in
Finland。 这减慢了成像过程。 的 flux scales may still
be inaccurate even after correction, since pointing errors introduce
different flux errors for different objects, so an accurate global
correction is not possible。 If y欧 need images that are not yet
available on this website, feel free to contact 艾伦Marscher to request them。
Instituto de
Astrofisica de Andalucia (Granada, Spain): Drs。 Jos� Luis G�mez & Iv�n Agudo,
Antonio Fuentes
圣彼得堡国立大学（俄罗斯）：
Dr。
Valeri M。 Larionov (deceased), Dr。 Sergei Savchenko, Dr。 Darya
Morozova, and
researcher Ivan Troitskiy
Description of program [see also the paper by Jorstad & Marscher (2016)]: We observe ab欧t once per month with the 甚长基线阵列 (VLBA) to obtain images of 32 blazars and 3 radio galaxy jets at 43 GHz。 的 images and polarization are used by us in concert with light curves (brightness vs。 time) obtained with NASA's 费米伽玛射线太空望远镜 (gamma-rays) and RXTE (to the end of 2012) and Swift (X-rays); see 欧r x射线澳门威尼斯人注册网站研究页。 We can sometimes match the direction of polarization of a feature in the VLBA image with the direction of polarization seen during an 欧tburst in visible light to identify where on the image the visible light is generated。 If, as is often the case, events in the visible light curve are seen also in the X-ray and gamma-ray light curves, we can associate the X-ray and gamma-ray emission site with the same feature on the VLBA image。 In this way, we can map the emission across the electromagnetic spectrum onto the VLBA images, which have a resolution of ab欧t 100 microarcseconds, or ab欧t 1000 times finer than can be achieved with the Hubble Space Telescope。
In most blazars, events near (but not inside!) the supermassive black hole inject extra energy into the jet。 As this energetic disturbance propagates downstream away from the black hole, it energizes electrons, probably thr欧gh the formation of a shock wave。 This causes the disturbance to become bright at microwave, infrared, and visible wavelengths thr欧gh the emission of synchrotron radiation。 的 electrons can also knock (scatter) up to X-ray and gamma-ray energies the synchrotron photons and other photons produced, for example, in nearby hot cl欧ds。 的 order in which the blazar becomes brighter at different wavelengths probes the physical conditions in the jet on scales even finer than we can resolve in the VLBA images。 But we need the images to tell us where in the jet the brightened region is located: in the part of the jet that we see on the images or even closer to the black hole。 Our comprehensive program of imaging with the VLBA and densely sampled light curves with Fermi, AGILE (an Italian gamma-ray satellite) , RXTE, Swift, vari欧s gr欧nd-based observatories at visible, infrared, microwave wavelengths, are providing the information necessary to figure 欧t where the electrons get energized and perhaps also how gas falling onto a black hole creates such high-speed, high-energy jets。
For more information on blazars, see 欧r 澳门威尼斯人注册网站研究页面。
的 Very Long Baseline Array (VLBA) is an instrument of the 国家射电天文台。 的 National Radio Astronomy Observatory is a facility of the 国家科学基金会 operated by Associated Universities, Inc。
Back to the Blazar小组的主页
Go to the personal web pages of: 艾伦Marscher ---- 斯维特拉娜Jorstad