Cosmological chemodynamical simulations are nowadays among the best tools to study how chemical elements are produced within galaxies, to reconstruct also the spatial distribution of the chemical elements as a function of time within different galaxy environments. Our simulation code includes the main stellar nucleosynthetic sources in the cosmos (core-collapse and Type Ia supernovae, hypernovae, asymptotic giant branch stars, and stellar winds from stars of all masses and metallicities). We present the predictions of our simulation for the evolution of the radial gradients of O/H, N/O and C/N in the gas-phase of a sample of ten star-forming disc galaxies, all characterised by very different star formation histories at the present time (see Figure 1.). On average, our simulated disc galaxies show a clear inside-out growth of the stellar mass as a function of time, and more negative slopes of the radial gas-phase O/H versus radius at earlier epochs of the galaxy evolution; we predict negative slopes of N/O and positive slopes of C/N at almost all redshifts, because of the main secondary origin of N in stars, even though the high-redshift simulation data are highly scattered because of the more turbulent conditions of the interstellar medium. Finally, we show that similar results are found with zoom-in simulations, where a spiral galaxy is re-simulated with a larger number of resolution elements. With zoom-in simulations, we study how stellar migrations (particularly old and metal-poor stellar populations migrating outwards) and radial gas flows are capable of influencing the galaxy chemical evolution at different galactic radii.

We examine the metallicity trends in the Milky Way (MW) bulge – using APOGEE DR13 data – and explore their origin by comparing two N-body models of isolated galaxies which develop a bar and a boxy/peanut (b/p) bulge. Both models have been proposed as scenarios for reconciling a disc origin of the MW bulge with a negative vertical metallicity gradient. The first is a superposition of co-spatial disc populations, different scaleheights and metallicities (with flat gradients) where the thick, metal-poor populations contribute significantly to the stellar mass budget in the inner galaxy. The second model is a single disc with an initial steep radial metallicity gradient which gets mapped by the bar into the b/p bulge in such a way that the vertical metallicity gradient of the MW bulge is reproduced – as shown already in previous works in the literature. As we show here, the latter model does not reproduce the positive longitudinal metallicity gradient of the inner disc, nor the metal-poor innermost regions seen in the data. The model with co-spatial thin and thick disc populations reproduces all the aforementioned trends. We therefore see that it is possible to reconcile a (primarily) disc origin for the MW bulge with the observed trends in metallicity by mapping the inner thin and thick discs of the MW into a b/p.

I will give here a very short summary of some of the work I have been doing lately on the chemical evolution in Milky-Way-like spiral galaxies.

In this contribution we introduce the motivation and goals of IAU Focus Meeting 8, “New Insights in Extragalactic Magnetic Fields”. We provide a background for the nine contributions included in these proceedings, as well as the online contributions. A recap of the meeting is provided in the form of audience feedback that was collected during the wrap-up session at the conclusion of FM8.

The standard picture for the origin of magnetic fields in astrophysical systems involves turbulent dynamo amplification of a weak seed field. Dynamos convert kinetic energy of motions to magnetic energy. While it is relatively easy for magnetic energy to grow, explaining the observed degree of coherence of cosmic magnetic fields generated by turbulent dynamos, remains challenging. We outline potential resolution of these challenges. Another intriguing possibility is that magnetic fields originated at some level from the early universe.

Blazar observations point toward the possible presence of magnetic fields over intergalactic scales of the order of up to ∼1 Mpc, with strengths of at least ∼10−16 G. Understanding the origin of these large-scale magnetic fields is a challenge for modern astrophysics. Here we discuss the cosmological scenario, focussing on the following questions: (i) How and when was this magnetic field generated? (ii) How does it evolve during the expansion of the universe? (iii) Are the amplitude and statistical properties of this field such that they can explain the strengths and correlation lengths of observed magnetic fields? We also discuss the possibility of observing primordial turbulence through direct detection of stochastic gravitational waves in the mHz range accessible to LISA.

Magnetic fields originate small-scale instabilities in the plasma of the intra-cluster medium, and may have a key role to understand particle acceleration mechanisms. Recent observations at low radio frequencies have revealed that synchrotron emission from galaxy clusters is more various and complicated than previously thought, and new types of radio sources have been observed. In the last decade, big steps forward have been done to constrain the magnetic field properties in clusters thanks to a combined approach of polarisation observations and numerical simulations that aim to reproduce Faraday Rotation measures of sources observed through the intra-cluster medium. In this contribution, I will review the results on magnetic fields reached in the last years, and I will discuss the assumptions that have been done so far in light of new results obtained from cosmological simulations. I will also discuss how the next generation of radio instruments, as the SKA, will help improving our knowledge of the magnetic field in the intra-cluster medium.

In these proceedings we discuss advances in the theory and observation of magnetic fields in the intergalactic medium and in the cosmic web. We make the point that, despite perhaps unsurmountable obstacles in simulating a small-scale dynamo, currently most cosmological magnetohydrodynamical simulations paint a similar picture of magnetic field amplification in the cosmos. However, observations of magnetic fields in the intergalactic medium turn out to be very difficult. As a case in point, we present recent work on Faraday rotation measurement in the direction of a giant galaxy with the Low Frequency Array (LOFAR). These observations demonstrate the currently unique capability of LOFAR to measure Faraday rotation at the high accuracy and angular resolution required to investigate the magnetisation of large-scale structure filaments of the cosmic web.

The unprecedented sensitivity, angular resolution and broad bandwidth coverage of Square Kilometre Array (SKA) radio polarimetric observations will allow us to address many long-standing mysteries in cosmic magnetism science. I will highlight the unique capabilities of the SKA to map the warm hot intergalactic medium, reveal detailed 3-dimensional structures of magnetic fields in local galaxies and trace the redshift evolution of galactic magnetic fields.

The next generation of radio telescopes offer significant improvement in bandwidth and survey speed. We examine the ability to resolve Faraday thick objects in Faraday space as a function of survey parameters. The necessary combination of λmax and λmin to resolve objects with modest Faraday thick components requires one or two surveys with instantaneous bandwidth 300 MHz to 750 MHz offered by next generation telescopes. For spiral galaxies, bandwidths in excess of 1.5 GHz are required. Correction for Galactic Faraday rotation must account for common gradients of order 10 rad m−2 per degree. How effective a new rotation measure grid is in probing the foreground depends on off-axis polarization calibration.

Recent numerical models of the multiphase ISM underline the importance of cosmic rays and magnetic fields for the physics of the ISM in disc galaxies. Observations of properties of the ISM in galactic halos constrain models of the expected exchange of matter between the star-forming disc and the environment (circumgalactic medium, CGM). We present new observational evidence from radio-continuum polarization studies of edge-on galaxies on magnetic field strength and structure as well as cosmic ray electron transport in galactic halos. The findings are discussed in the context of the disk-halo interaction of the interstellar medium. In addition, it is also briefly demonstrated how recent LOFAR observations of edge-on galaxies further constrain the extent of magnetic fields in galactic halos.

An excellent laboratory for studying large scale magnetic fields is the grand design face-on spiral galaxy M51. Due to wavelength-dependent Faraday depolarization, linearly polarized synchrotron emission at different radio frequencies gives a picture of the galaxy at different depths: Observations at L-band (1 – 2 GHz) probe the halo region while at C- and X-band (4 – 8 GHz) the linearly polarized emission probe the disk region of M51. We present new observations of M51 using the Karl G. Jansky Very Large Array (VLA) at S-band (2 – 4 GHz), where previously no polarization observations existed, to shed new light on the transition region between the disk and the halo. We discuss a model of the depolarization of synchrotron radiation in a multilayer magneto-ionic medium and compare the model predictions to the multi-frequency polarization data of M51 between 1 – 8 GHz. The new S-band data are essential to distinguish between different models. Our study shows that the initial model parameters, i.e. the total regular and turbulent magnetic field strengths in the disk and halo of M51, need to be adjusted to successfully fit the models to the data.

The new generation of radio interferometers will deliver an unprecedented amount of deep and high resolution observations. In this proceedings, we present recent algorithmic advances in the context of the study of cosmic magnetism in order to extract all the information contained in these data.

The use of 3D magneto-hydrodynamic simulations of the solar atmosphere in modeling irradiance variations seems a natural evolution of the current irradiance reconstruction techniques making use of one-dimensional, static, atmosphere models. Nevertheless, the development of such new models poses serious computational challenges. This contribution focuses on recent progresses made in the development of novel irradiance reconstruction models making use of 3D MHD simulations and discusses current and future challenges.

We review recent developments in combining solar irradiance datasets from different instruments to obtain one single composite, which is the key to understanding how irradiance varies on decadal timescales and beyond.

he Chromospheric Telescope (ChroTel) observes the entire solar disk since 2011 in three different chromospheric wavelengths: Hα, Ca ii K, and He i. The instrument records full-disk images of the Sun every three minutes in these different spectral ranges. The ChroTel observations cover the rising and decaying phase of solar cycle 24. We started analyzing the ChroTel time-series and created synoptic maps of the entire observational period in all three wavelength bands. The maps will be used to analyze the poleward migration of quiet-Sun filaments in solar cycle 24.

We consider several tracers of magnetic activity that separate cycle-dependent contributions to the background solar magnetic field from those that are independent of the cycle. The main message is that background fields include two relative separate populations. The background fields with a strength up to 100 Mx cm−2 are very poorly correlated with the sunspot numbers and vary little with the phase of the cycle. In contrast, stronger magnetic fields demonstrate pronounced cyclic behaviour. Small-scale solar magnetic fields demonstrate features of fractal intermittent behaviour, which requires quantification. We investigate how the observational estimate of the solar magnetic flux density B depends on resolution D in order to obtain the scaling In BD = −k In D + a in a reasonably wide range. The quantity k demonstrates cyclic variations typical of a solar activity cycle. k depends on the magnetic flux density, i.e. the ratio of the magnetic flux to the area over which the flux is calculated, at a given instant. The quantity a demonstrates some cyclic variation, but it is much weaker than in the case of k. The scaling is typical of fractal structures. The results obtained trace small-scale action in the solar convective zone and its coexistence with the conventional large-scale solar dynamo based on differential rotation and mirror-asymmetric convection. Here we discuss the message for solar dynamo studies hidden in the above results.

In this study, using the data of Istanbul University Observatory, general features of Solar Cycle 24 are presented.

Surface flux transport (SFT) models have been successful in reproducing how magnetic flux at the solar photosphere evolves on large scales. SFT modelling proved to be useful in reconstructing secular irradiance variations of the Sun, and it can be potentially used in forward modelling of brightness variations of Sun-like stars. We outline our current understanding of solar and stellar SFT processes, and suggest that nesting of activity can play an important role in shaping large-scale patterns of magnetic fields and brightness variability.