Optical and radio properties of extragalactic radio sources with recurrent jet activity

We present a sample of 74 radio sources with recurrent jet activity. The sample consists of 67 galaxies, 2 quasars and 5 unidentified sources, selected from the published data or are newly recognized. The sample's redshift range is 0.002 < z < 0.7 and the size of inner and outer structures varies from 0.02 to 4248 kpc. We analyse the optical and radio properties of the sample and compare them with the characteristics of ordinary one-off FRII radio sources. With the help of stellar population modelling, we derive black hole masses and stellar masses of host galaxies of 35 restarting radio sources, finding that the black hole masses in restarting radio sources are comparable to those of typical single-cycle FRII radio sources. The obtained median values of log M$_{BH}$ are 8.58 and 8.62 M$_{\odot}$ Unlike the black hole masses, the stellar masses in restarting radio sources tend to be smaller than in the FRII sources. Although the stellar populations of the hosts of recurrent activity sources are dominated by old stars, a significant fraction of young stars can be observed as well. Based on the Sloan Digital Sky Survey photometric observations, we also analyse the morphology of the host galaxies and obtained significantly smaller concentration indices for the restarting radio sources when compared to the classical FRII hosts. This effect can be interpreted as a result of frequent merger events in the history of host galaxies of restarting radio sources.Comment: 21 pages, 17 figure

The magnetic fields of large Virgo cluster spirals: Paper II

The Virgo cluster of galaxies provides excellent conditions for studying interactions of galaxies with the cluster environment. Both the high-velocity tidal interactions and effects of ram pressure stripping by the intracluster gas can be investigated in detail. We extend our systematic search for possible anomalies in the magnetic field structures of Virgo cluster spirals in order to characterize a variety of effects and attribute them to different disturbing agents. Six angularly large Virgo cluster spiral galaxies (NGC4192, NGC4302, NGC4303, NGC4321, NGC4388, and NGC4535) were targets of a sensitive total power and polarization study using the 100-m radio telescope in Effelsberg at 4.85GHz and 8.35GHz (except for NGC4388 observed only at 4.85GHz, and NGC4535 observed only at 8.35GHz). Magnetic field structures distorted to various extent are found in all galaxies. Three galaxies (NGC4302, NGC4303, and NGC4321) show some signs of possible tidal interactions, while NGC4388 and NGC4535 have very likely experienced strong ram-pressure and shearing effects, respectively, visible as distortions and asymmetries of polarized intensity distributions. As in our previous study, even strongly perturbed galaxies closely follow the radio-far-infrared correlation. In NGC4303 and NGC4321, we observe symmetric spiral patterns of the magnetic field and in NGC4535 an asymmetric pattern. Magnetic fields allow us to trace even weak interactions that are difficult to detect with other observations. Our results show that the degree of distortions of a galaxy is not a simple function of the distance to the cluster center but reflects also the history of its interactions. The angle between the velocity vector and the rotation vector of a galaxy may be a general parameter that describes the level of distortions of galactic magnetic fields.Comment: 12 pages, 18 figures, 2 tables. Accepted for publication in Astronomy and Astrophysic

Hot gas and magnetic arms of NGC 6946 : indications for reconnection heating?

Context. The grand-design face-on spiral galaxy NGC 6946 is remarkable because of its high star formation activity, the massive northern spiral arm, and the magnetic arms, which are observed in polarized radio synchrotron emission and are located between the optical arms and possibly are magnetic reconnection regions. Aims. We used electron densities and temperatures in star-forming (active) and less active regions and compared them to findings from the analysis of the radio data to study the energy budget of NGC 6946. The hot gas above the magnetic arms between the optical arms might suggest gas heating by reconnection. We also study the population of point sources in NGC 6946, including the origin of the puzzling ultra-luminous emission complex MF16. Methods. X-ray observations of NGC 6946 performed with XMM-Newton were used to study the emission from X-ray point sources and diffuse hot gas, including the magnetic arms and the halo. Spectral fitting of the diffuse X-ray emission allowed us to derive temperatures of the hot gas. With assumptions about the emission volume, this allowed us to estimate gas densities, masses, and cooling times. Results. To explain the X-ray emission from the spiral arms of NGC 6946 two-temperature plasma models are needed to account for the disk and halo emission. The interarm regions show only one thermal component. We observe that the temperature of the hot gas in and above the magnetic arm regions increases slightly when compared to the average temperatures in the areas in and above the spiral arms. For the southwestern part of the disk, which is depolarized in the radio range by Faraday rotation, we find more efficient mixing of disk and halo gas. Conclusions. We propose magnetic reconnection in the magnetic arm regions of NGC 6946 as the possible cause of the additional heating of the gas and ordering of the magnetic fields. In the southwestern part of the galactic disk we observed indications of a possible faster outflow of the hot gas. A very hot gas within the MF 16 nebula possibly suggests shock heating by a supernova explosion

Multifrequency analysis of the radio emission from a post-merger galaxy CGCG 292-057

Galaxies exhibiting a specific large-scale extended radio emission, such as X-shaped radio galaxies, belong to a rare class of winged radio galaxies. The morphological evolution of these radio sources is explained using several theoretical models, including galaxy mergers. However, such a direct link between a perturbed radio morphology and a galaxy merger remains observationally sparse. Here we investigate a unique radio galaxy J1159+5820, whose host CGCG 292-057 displays the optical signature of a post-merger system with a distinct tidal tail feature, and an X-shaped radio morphology accompanied by an additional pair of inner lobes. We observed the target on a wide range of radio frequencies ranging from 147 MHz to 4959 MHz, using dedicated GMRT and VLA observations, and supplemented it with publicly available survey data for broadband radio analysis. Particle injection models were fitted to radio spectra of lobes and different parts of the wings. Spectral ageing analysis performed on the lobes and the wings favors a fast jet realignment model with a reorientation timescale of a few million years. We present our results and discuss the possible mechanisms for the formation of the radio morphology.Comment: 13 pages, 9 figures, Accepted for publication in MNRA

Tangible and intangible heritage of Central Europe in the practices of the International Cultural Center in Cracow

Międzynarodowe Centrum Kultury w Krakowie to instytucja, która od lat działa na rzecz popularyzacji i ochrony dziedzictwa kulturowego Europy Środkowej. Celem niniejszego artykułu jest pokazanie specyfiki tej instytucji oraz ukazanie różnorodności działań podejmowanych przez MCK: od wystaw, przez działania edukacyjne w postaci prelekcji i warsztatów, po konferencje i publikacje (o charakterze popularyzatorskim i naukowym). Zestawiając te działania, w których MCK pokazuje zarówno twórczość konkretnych artystów, jak i przybliża historię oraz dziedzictwo poszczególnych narodów, a wreszcie sięga do idei i fenomenów (takich jak Kresy czy mit Galicji), które są istotnym elementem kulturowej spuścizny Europy Środkowej, ukazuję, że działania te wpisują się w humanistyczne myślenie o dziedzictwie kulturowym. Pokazuję też korelację między tematyką organizowanych wystaw i innych wydarzeń a miejscem, czyli miastem, w którym działa MCK. Wszystkie te przykłady potwierdzają, że MCK, jako autorski projekt, jest nowoczesną instytucją o interdyscyplinarnym podejściu i charakterze. Pełni ono funkcję zarówno muzeum, jak i placówki edukacyjno-naukowej oraz dyplomatycznej - dbając (w myśl polityki "soft power") o budowanie dobrosąsiedzkich relacji między Polską i innymi państwami z tej części kontynentu. Prezentowane praktyki są potwierdzeniem realizacji misji MCK, którą jest kształtowanie i propagowanie nowego podejścia do europejskiego dziedzictwa: z jednej strony akcentującego kwestie tożsamości, tradycji i rodzimości poszczególnych kultur, z drugiej - otwartego na dialog międzykulturowy, będący istotnym wyzwaniem i znakiem współczesności.Tangible and Intangible Heritage of Central Europe in the Practices of the International Cultural Center in Cracow The International Cultural Center in Cracow is an institution that has been working for years to popularize and protect the cultural heritage of Central Europe. The purpose of this article is to show the peculiarities of this institution and to demonstrate the variety of activities undertaken by the ICC: from exhibitions, through educational activities in the form of lectures and workshops, to conferences and publications (of a popularizing and scientific nature). By juxtaposing these activities, in which the ICC showcases both the work of specific artists and brings the history and heritage of individual nations closer, and finally reaches out to ideas and phenomena (such as the Borderlands or the myth of Galicia) that are an important element of the cultural legacy of Central Europe, I show that these activities are part of humanistic thinking about cultural heritage. I also show the correlation between the themes of the exhibitions and other events organized and the place, i.e., the city with which the ICC works. All these examples show that the Center, as an original project, is a modern institution with an interdisciplinary approach and character. It performs the role of both a museum and an educational and scientific institution, as well as a diplomatic one - taking care (in accordance with the "soft power" policy) of building good neighborly relations between Poland and other countries from this part of the continent. The presented practices are a confirmation of the realization of the ICC's mission, which is to shape and promote a new approach to European heritage: on the one hand emphasizing the issues of identity, tradition and indigenousness of individual cultures, on the other hand, open to intercultural dialogue, which is an important challenge and a sign of contemporarity

Dialog about the modern identity of Polish Jews : around the postmemory narrations in documentary by Mikołaj Grynberg The Proof of Identity

Film dokumentalny Dowód tożsamości z 2021 r. był debiutem reżyserskim Mikołaja Grynberga. W filmie tym reżyser stara się przedstawić wyjątkowe doświadczenie bycia polskim Żydem, jednocześnie badając zawiłą naturę esencjalnie podwójnej (polsko-żydowskiej lub żydowsko-polskiej) tożsamości. Celem tego artykułu jest wyjaśnienie ram zastosowanych zarówno przez reżysera, jak i jego bohaterów w opowiadaniu o poszukiwaniu dowodu tożsamości, co pociąga za sobą pogodzenie się z osobistą (i rodzinną) pamięcią. Artykuł zagłębia się w "konflikty" i "negocjacje", które pojawiają się w rozważaniach badanych osób na temat tożsamości w kontekście postpamięci. Kluczowe dla filmu jest fundamentalne pytanie reżysera: Co to znaczy być Żydem w dzisiejszej Polsce? Integralnym aspektem tych rozważań jest analiza faktu, że autor, znany przede wszystkim jako pisarz, wybrał formę dokumentu, którego szczególnym rodzajem jest wywiad.The 2021 documentary The Proof of Identity marked the directorial debut of Mikołaj Grynberg. In this film, the director attempts to depict the unique experience of being a Polish Jew, while also exploring the intricate nature of an essentially dual (Polish-Jewish or Jewish-Polish) identity. The aim of this article is to elucidate the framework employed by both the director and his characters in recounting their search for a proof of identity, which entails coming to terms with personal (and familial) memory. The article delves into the "conflicts" and "negotiations" that arise in the interviewed individuals' considerations of identity within the context of postmemory. Central to the film is the director's fundamental question: What does it mean to be a Jew in present-time Poland? An integral aspect of these considerations is the examination of the fact that the author, who is primarily known as a writer, chose the form of documentary, with the interview as its special type

From disappearance to re-remembrance : post-memory narration about Miedzianka

Miedzianka - a lower Silesian village, earlier: mining town and a leisure-tourist resort, ger. Kupferberg. It is said that it is a ghost-town, which has (almost) diaappeared. Some traces, however, remained - a church, photography or human memories - both from before World War II, of German citizens and after the world war of polish inhabitants. All of them are connected by the traumatic experience that combines post-war resettlement and the destruction of the town. The memory of Miedzianka was not destroyed, though, being passed to next generations. One of the voices of this post-memory can be found in the report by Filip Springer, Miedzianka: Story of Disappearing in 2011. This book quickly became recognised ensuing an increasing interest in the town, its history and fate, making new post-memory narrations to appear, which I describe as "post-memory practice". One of them is Miasto, którego nie było (The City, which didn’t exist). What and how do these books tell us about Miedzianka? In what sense do these alternative but interpenetrating narrations influence the perception of this place, as well as the memory of it? These questions are the basis of the reflections leading to a display of relations between man and his oblivion/memory and the place. The literature, however, or widely art, having the power to preserve memory and therefore to save, allows the showcasing of the transformation of the town: its history, disappearance, and finally transubstantiation into a place of memory, which is created mainly by the second and third generations - heritage depositories

Materialne i niematerialne dziedzictwo Europy Środkowej w praktykach Międzynarodowego Centrum Kultury w Krakowie

The International Cultural Center in Cracow is an institution that has been working for years to popularize and protect the cultural heritage of Central Europe. The purpose of this article is to show the peculiarities of this institution and to demonstrate the variety of activities undertaken by the ICC: from exhibitions, through educational activities in the form of lectures and workshops, to conferences and publications (of a popularizing and scientific nature). By juxtaposing these activities, in which the ICC showcases both the work of specific artists and brings the history and heritage of individual nations closer, and finally reaches out to ideas and phenomena (such as the Borderlands or the myth of Galicia) that are an important element of the cultural legacy of Central Europe, I show that these activities are part of humanistic thinking about cultural heritage. I also show the correlation between the themes of the exhibitions and other events organized and the place, i.e., the city with which the ICC works. All these examples show that the Center, as an original project, is a modern institution with an interdisciplinary approach and character. It performs the role of both a museum and an educational and scientific institution, as well as a diplomatic one – taking care (in accordance with the “soft power” policy) of building good neighborly relations between Poland and other countries from this part of the continent. The presented practices are a confirmation of the realization of the ICC’s mission, which is to shape and promote a new approach to European heritage: on the one hand emphasizing the issues of identity, tradition and indigenousness of individual cultures, on the other hand, open to intercultural dialogue, which is an important challenge and a sign of contemporarity.Międzynarodowe Centrum Kultury w Krakowie to instytucja, która od lat działa na rzecz popularyzacji i ochrony dziedzictwa kulturowego Europy Środkowej. Celem niniejszego artykułu jest pokazanie specyfiki tej instytucji oraz ukazanie różnorodności działań podejmowanych przez MCK: od wystaw, przez działania edukacyjne w postaci prelekcji i warsztatów, po konferencje i publikacje (o charakterze popularyzatorskim i naukowym). Zestawiając te działania, w których MCK pokazuje zarówno twórczość konkretnych artystów, jak i przybliża historię oraz dziedzictwo poszczególnych narodów, a wreszcie sięga do idei i fenomenów (takich jak Kresy czy mit Galicji), które są istotnym elementem kulturowej spuścizny Europy Środkowej, ukazuję, że działania te wpisują się w humanistyczne myślenie o dziedzictwie kulturowym. Pokazuję też korelację między tematyką organizowanych wystaw i innych wydarzeń a miejscem, czyli miastem, w którym działa MCK. Wszystkie te przykłady potwierdzają, że MCK, jako autorski projekt, jest nowoczesną instytucją o interdyscyplinarnym podejściu i charakterze. Pełni ono funkcję zarówno muzeum, jak i placówki edukacyjno-naukowej oraz dyplomatycznej – dbając (w myśl polityki „soft power”) o budowanie dobrosąsiedzkich relacji między Polską i innymi państwami z tej części kontynentu. Prezentowane praktyki są potwierdzeniem realizacji misji MCK, którą jest kształtowanie i propagowanie nowego podejścia do europejskiego dziedzictwa: z jednej strony akcentującego kwestie tożsamości, tradycji i rodzimości poszczególnych kultur, z drugiej – otwartego na dialog międzykulturowy, będący istotnym wyzwaniem i znakiem współczesności

Dynamical analysis of the complex radio structure in 3C 293 : clues on a rapid jet realignment in X-shaped radio galaxies

Context. Radio galaxies classified as X-shaped/winged, are characterised by two pairs of extended and misaligned lobes, which suggest a rapid realignment of the jet axis, for which a potential cause (including binary supermassive black holes, a black hole merger, or a Lense-Thirring precession) is still under debate. Aims. Here we analyse the complex radio structure of 3C 293 winged source hosted by the post-merger galaxy UGC 8782, which uniquely displays a significant asymmetry between the sizes (and therefore the ages) of the two pairs of lobes, indicating that an episode of jet realignment took place only very recently. This allows us to tightly constrain the corresponding timescales, and therefore to discriminate between different models proposed for the formation of X-shaped radio galaxies in general. Methods. Based on all the available and carefully re-analysed radio data for 3C 293, we have performed a detailed spectral modelling for the older and younger lobes in the system, using the existing evolutionary DYNAGE algorithm. In this way we derived the lobes’ ages and jet energetics, which we then compared to the accretion power in the source. Results. We found that the 200 kpc-scale outer lobes of 3C 293 are ~ 60 Myr old and, until very recently, have been supplied with fresh electrons and magnetic field by the jets, i.e., jet activity related to the formation of the outer lobes ceased within the last Myr. Meanwhile, the inner 4 kpc-scale lobes, tilted by ~ 40° with respect to the outer ones, are only about ~ 0.3 Myr old. Interestingly, the best model fits also return identical values of the jet power supplying the outer and the inner structures. This power, moreover, is of the order of the maximum kinetic luminosity of a Blandford-Znajek jet for a given black hole mass and accretion rate, but only in the case of relatively low values of a black hole spin, a ~ 0.2. Conclusions. The derived jet energetics and timescales, along with the presence of two optical nuclei in UGC 8782, all provide a strong support to the Lense-Thirring precession model in which the supermassive black hole spin, and therefore the jet axis, flips rapidly owing to the interactions with the tilted accretion disk in a new tidal interaction episode of the merging process. We further speculate that, in general, X-shape radio morphology forms in post-merger systems that are rich in cold molecular gas, and only host slowly spinning supermassive black holes

Tidal interaction vs. ram pressure stripping effects as seen in X-rays. Hot gas in group and cluster galaxies

The hot intracluster/intragroup medium (ICM/IGM) and a high galaxy density can lead to perturbations of the galactic interstellar medium (ISM) due to ram pressure and/or tidal interaction effects. In radio polarimetry observations, both phenomena may manifest similar features. X-ray data can help to determine the real origin of the perturbation. We analyse the distribution and physical properties of the hot gas in the Virgo cluster spiral galaxies NGC 4254 and NGC 4569, which indicate that the cluster environment has had a significant influence on their properties. By performing both spatial and spectral analyses of X-ray data, we try to distinguish between two major phenomena: tidal and ram pressure interactions. We compare our findings with the case of NGC 2276, in which a shock was reported, by analysing XMM-Newton X-ray data for this galaxy. We use archival XMM-Newton observations of NGC 4254, NGC 4569, and NGC 2276. Maps of the soft diffuse emission in the energy band 0.2 - 1 keV are obtained. For the three galaxies, especially at the position of magnetic field enhancements we perform a spectral analysis to derive gas temperatures and thus to look for shock signatures. A shock is a signature of ram pressure resulting from supersonic velocities; weak tidal interactions are not expected to influence the temperature of the ionized gas. In NGC 4254, we do not observe any temperature increase. This suggests tidal interactions rather than ram pressure stripping. In NGC 4569 the radio polarized ridge shows a higher temperature, which may indicate ram-pressure effects. For NGC 2276, we do not find clear indications of a shock. The main driver of the observed distortions is most likely tidal interaction. Determining gas temperatures via sensitive X-ray observations seems to be a good method for distinguishing between ram pressure and tidal interaction effects acting upon a galaxy.Comment: 13 pages, 13 figures, 8 tables, Accepted for publication in Astronomy and Astrophysic