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--- evn:evn_science [2017/08/07 12:20] – [No AGN evidence in NGC 1614 from deep radio VLBI observations] michael.lindqvist
+++ evn:evn_science [2018/09/12 09:15] – antonis
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-[[http://www.jive.eu/jivewiki/doku.php?id=evn:guidelines|The next deadline is October 1, 2017]].
+[[http://www.jive.eu/jivewiki/doku.php?id=evn:guidelines|The next deadline is October 1, 2018]].
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+=====Gravitationally-lensed radio arcs observed with global VLBI=====
+The Strong lensing at High Angular ResoluTon Program (SHARP) led by McKean (ASTRON) has
+obtained a deep global VLBI observaTon of the gravitaTonal lens MG J0751+2716 at 1.65 GHz
+(project GM070; PI: McKean). The 18.5 hours observation used 24 antennas from the EVN and
+the VLBA, including the large apertures (> 50 m) of the Lovell, Effelsberg, Robledo and Green Bank
+telescopes. Data were recorded at 512 Mbps and correlated at JIVE to produce 8 spectral
+windows (IFs) with 8 MHz bandwidth and 32 channels each, through both circular polarisaTons.
+MG J0751+2716 is one of the few quadruply imaged radio-loud gravitationally lensed quasars that
+show extended arcs on VLBI-scales. The global VLBI L-band deep imaging detects all of the extended
+arcs at high significance, showing the complex surface brightness structure of the background
+source in unprecedented detail (see Figure from [[https://doi.org/10.1093/mnras/sty1326|Spingola et al (2018)]]). Because of the complexity of this system, the imaging was
+performed using multi-scale cleaning within the wsclean algorithm (Offringa et al. 2014). The total
+flux density of the target is 350 mJy and the off-source rms is 41 μJy/beam. Never before have such
+extended (200-600 mas) gravitaTonal arcs been detected at an angular resoluTon of a few mas. The
+excellent uv-coverage and surface brightness sensiTvity provided by the global VLBI array have been
+fundamental for a precise study of the structure of the extended arcs on mas-scales from
+MG J0751+2716.
+{{:evn:grav_lens_spingola.jpeg?400|}}
+**Figure 1.**Global VLBI imaging of MG J0751+2716 at 1.65 GHz (Spingola et al. (2018)). The off-source
+rms is 41 μJy/beam and the peak surface brightness is 2.9 mJy/beam. The restored beam is 5.5x1.8
+mas, and is shown within the white box in the bottom-hand corner.
 ===== The Repeating Fast Radio Burst FRB 121102 as seen on milliarcsecond angular scales =====
 [[http://www.nature.com/nature/journal/v541/n7635/full/nature20797.html | Chatterjee et al. (2017) ]] has been able to locate (with a 100 mas precision) the repeating FRB 121102. This has led to its unambiguous association with persistent radio and optical counterparts, and to the identification of its host galaxy. However, an even more precise localization is needed in order to probe the direct physical relationship between the millisecond bursts themselves and the associated persistent emission.
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 [[https://academic.oup.com/mnrasl/article-lookup/doi/10.1093/mnrasl/slx085| Herrero-Illana et al. (2017)]] present deep dual-band 5.0- and 8.4 GHz EVN observations of NGC 1614, a local luminous infrared galaxy with a powerful circumnuclear starburst ring, and whose nuclear engine origin is still controversial. The aim was to detect and characterize any compact radio structures both in the nuclear region and in the circumnuclear ring. They did not find any compact source in the central 200 pc region. However, they do detect a compact source in the circumnuclear ring located about 0.6 arcsec (190 pc) to the north of the nucleus. Its luminosity and spectral shape are indicative of a SN origin, possibly a Type IIn or Ic. Their result favours the pure starburst scenario, even for the nucleus of NGC 1614.
+{{ :evn:slx085fig2.jpeg?600 |}}
+**Figure 7.**
+EVN maps of the detected compact source at the C band (5.0 GHz; left-hand panel) and the X band (8.4 GHz; right-hand panel).