AO 0235+164 is a blazar located at redshift \(z=0.94\), that is, more than \(\mathrm{6200 ~ Mpc}\) or \(2\times10^{10} ~ \text{light years}\) away from Earth. It is believed that the supermassive black hole at its center harbors more than 10 million of solar masses. An article about it by VHEGA group member Juan Escudero Pedrosa features in this monthly issue of Astronomy & Astrophysics.

Blazars are amongst the brightest objects in the universe. They are known to consist of a supermassive black hole at the center of a galaxy with a powerful jet that accelerates particles at speeds close to that of light towards us. These speeds make relativistic effects absolutely crucial to understand what we are seeing. They present periods of activity where their luminosity increases by several orders of magnitude, making them easily visible despite their distance. However, many questions remain about the exact mechanisms of emission and the particles involved.

The new article studies the emission of AO 0235+164 from a multi-wavelength perspective, gathering data from 7mm VLBI images to high-energy \(\gamma\)-rays. The article finds that emission is probably located at several parsecs away from the central black hole. It also studies its interesting x-ray behavior, proposing a model where the x-ray emission comes from a different zone located much closer to the central black hole based on the analysis of correlations, kinematic analysis of the jet, and spectral energy distribution modelling.

Link to the article: https://www.aanda.org/articles/aa/abs/2024/02/aa46885-23/aa46885-23.html

The extreme Universe will never cease to amaze us! The LST-1 telescope has detected significant gamma-ray emission from the distant blazar OP 313, discovering for the first time this source in the very-high-energy gamma-ray band (see the published ATel). It is also the first discovery made by the LST-1 telescope of the Cherenkov Telescope Array Observatory (CTAO). This detection comes after several days of enhanced activity from this source observed by the Fermi-LAT telescope.

This motivated the observations performed by LST-1 between December 10th and December 14th, resulting in the detection of this source for the very first time at the highest energies. More interestingly, this distant blazar, located at a redshift z=0.997 (approximately 10 billion light years away from us!), is the furthest blazar ever detected at such energies. This discovery is another proof of the great potential of the upcoming CTAO.

This discovery involved several researchers and members of the LST-1 Collaboration, with VHEGA members Daniel Morcuende and Jorge Otero Santos leading the analysis of the data taken with LST-1. In addition, the group has also monitored this blazar with optical photometric and polarimetric observations using the telescopes at the Sierra Nevada Observatory, providing broader coverage along the electromagnetic spectrum.

For more information, check the CTAO and IAA press releases.

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Image credits: CTAO gGmbH, NASA, ESA, J. Olmsted (STScI).

On September 29th 2023, the visiting student Giulia Brunelli defended her Master’s thesis “Very-High Energy gamma-ray observations of the Geminga pulsar with the LST-1 of CTA” (available here) in front of the Graduation Board of the Master Degree Programme of the University of Bologna. She graduated in Astrophysics and Cosmology with 110 out of 110, with honours.

In Italian universities, the word to address a student who has graduated is laureato because of the tradition of wearing a laurel wreath after the graduation (laurea, in Italian) ceremony. The wreath is decorated with flowers or small berries, and a bow whose colour depends on the course of study. For the Physics and Astronomy department in Bologna, the colour is dark green.

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