Taking secondary particles produced from dark matter (DM) annihilation process to the origin of the extended diffuse radio emission observed in galaxy clusters, we studied both their morphology and radio spectral profile using simulated Coma like galaxy clusters. We have considered a neutralino annihilation channel dominated by $b\overline b $ species with a branching ratio of 1 and neutralino mass of 35 GeV with annihilation cross-section of 1×10-26 cm3 s-1. The radio emission maps produced for the two simulated galaxy clusters which are based on the MUsic SImulation of galaxy Clusters (MUSIC) dataset reveal the observed radio halo morphology showing radio emission both from the central regions of the cluster and substructures lying out off cluster centre. The flux density curve is in a good agreement for ν ≤ 2 GHz with the obsevational values for the Coma cluster of galaxies showing a small deviation at higher frequencies.

The intrinsic oxygen fugacity of a planet profoundly influences a variety of its geochemical and geophysical aspects. Most rocky bodies in our solar system formed with oxygen fugacities approximately five orders of magnitude higher than that corresponding to a hydrogen-rich gas of solar composition. Here we derive oxygen fugacities of extrasolar rocky bodies from the elemental abundances in 15 white dwarf (WD) stars polluted by accretion of rocks. We find that the intrinsic oxygen fugacities of rocks accreted by the WDs are similar to those of terrestrial planets and asteroids in our solar system. This result suggests that at least some rocky exoplanets are geophysically and geochemically similar to Earth.

We investigate the relationship between environment and star formation main sequence (the relationship between stellar mass and star formation rate) to shed new light on the effects of the environments on star-forming galaxies. We use the large VLA-COSMOS 3 GHz catalogue that consist of star-forming galaxies (SFGs) and active galactic nuclei (AGN) in three different environments (field, filament, cluster) and for different galaxy types. We examine for the first time a comparative analysis for the distribution of SFGs with respect to the star formation main sequence (MS) consensus region from the literature, taking into account galaxy environment and using radio selected sample at 0.1 ≤ z ≤ 1.2 drawn from one of the deepest COSMOS radio surveys. We find that, as observed previously, SFRs increase with redshift independent on the environments. Furthermore, we observe that SFRs versus M* relation is flat in all cases, irrespective of the redshift and environments.

By means of numerical simulations we study the radial-orbit instability in anisotropic self-gravitating N–body systems under the effect of noise. We find that the presence of additive or multiplicative noise has a different effect on the onset of the instability, depending on the initial value of the orbital anisotropy.

We present MIR spectroscopy and photometry obtained with CanariCam on the 10.4 m Gran Telescopio CANARIAS for a sample of 20 nearby, MIR bright and X-ray luminous quasi-stellar objects (QSOs). We find that for the majority of QSOs the MIR emission is unresolved at angular scales ∼0.3 arcsec. We derive the properties of the dusti tori that surround the nucleus based on these observations and find significant differences in the parameters compared with a sample of Seyfert 1 and 2 nuclei. We also find evidence for polycyclic aromatic hydrocarbon (PAH) features in the spectra, indicative of star formation, more centrally peaked (on scales of a few hundred pc) than previously believed.

We analyze the molecular and atomic gas data from the GALEX Arecibo SDSS Survey (xGASS) and the extended CO Legacy Database (xCOLD GASS) IRAM survey using novel survival analysis techniques to identify a small number of stellar properties that best correlate with the gas mass. We find that the dust absorption, AV, and the stellar half-light radius, R50, are likely the two best secondary parameters than improve the Kennicutt - Schmidt type relation between the gas mass and the star formation rate, SFR. We fit multiple regression, taking into account gas mass upper limits, to summarize the median, mean, and the 0.15/0.85 quantile multivariate relationships between the gas mass (atomic or molecular hydrogen), SFR, AV and/or R50. In particular, we find that the AV of both the stellar continuum and nebular gas emission shows a significant partial correlation with the molecular hydrogen after controlling for the effect of SFR. The partial correlation between the AV and the atomic gas, however, is weak and their zero-order correlation may be explained by SFR. This is expected since in poorly dust-shielded regions molecular hydrogen is dissociated by the far ultraviolet photons and HI is the dominant phase. Similarly, R50 shows significant partial correlations with both atomic and molecular gas masses. This hints at the importance of environment (e.g., galacto-centric distance) on the gas contents galaxies and on the interplay between gas and star formation rate. We apply the gas scaling relations we found to a large sample of type 2 and type 1 AGNs and infer that the gas mass correlates with AGN luminosity. This correlation is inconsistent with the prediction of AGN feedback models that strong AGNs remove or heat cold gas in their host galaxies.

Currently, the Transiting Exoplanet Survey Satellite (TESS) searches for Earth-size planets around nearby dwarf stars. To identify specific weak variations in the light curves of stars, sophisticated data processing methods and analysis of the light curve shapes should be developed and applied. We report some preliminary results of our project to find and identify minima in the light curves of stars collected by TESS and stored in the MAST (Mikulski Archive for Space Telescopes) database. We developed Python code to process the short-cadence (2-min) TESS PDCSAP (Pre-search Data Conditioning Simple Aperture Photometry) light curves. Our code allows us to create test samples to apply machine learning methods to classify minima in the light curves taking into account their morphological signatures. Our approach will be used to find and analyze some sporadic events in the observed light curves originating from transits of comet-like bodies.

With the success of the Cassini-Huygens mission, the dynamic complexity surrounding natural satellites of Saturn began to be elucidated. New ephemeris could be calculated with a higher level of precision, which made it possible to study in detail the resonant phenomena and, in particular, the 54:53 near mean-motion resonance between Prometheus and Atlas. For this task, we have mapped in details the domains of the resonance with dense sets of initial conditions and distinct ranges of parameters. Our initial goal was to identify possible regions in the phase space of Atlas for which some critical angles, associated with the 54:53 mean motion have a stable libration. Our investigations revealed that there is no possibility for the current Atlas orbital configuration to have any regular behavior since it is in a chaotic region located at the boundary of the 54:53 mean-motion resonance phase space. This result is in accordance with previous works (Cooper et al. 2015; Renner et al. 2016). In this work, we generalize such investigations by showing detailed aspects of the Atlas-Prometheus 54:53 mean-motion resonance, like the extension of the chaotic layers, the thin domain of the center of the 54:53 resonance, the proximity of other neighborhood resonances, among other secondary conclusions. In particular, we have also shown that even in the deep interior of the resonance, it is difficult to map periodic motion of the resonant pair for very long time spans.

We have constructed an all-sky AGN catalogue, based on optical spectroscopy, from the parent sample of galaxies in the 2MASS Redshift Survey (2MRS), a near-complete census of the nearby (z < 0.09) universe. In addition to identifying the 8491 AGNs and providing line measurements for all the emission line galaxies so that the users can customise the selection criteria, we assess the affects of spectral quality on AGN identification. We find that spectral signal-to-noise and resolution affect not only the overall AGN detection rates but also the broad-line to narrow-line AGN ratios. These systematic effects must be taken into account when using any optical AGN catalogue and in comparing the results from different catalogues. We develop a way to account for the inhomogeneities by parametrizing the AGN detection rates as a function of the spectral signal-to-noise, making our catalogue suitable for statistical analyses. We will also present cross-correlation studies between this catalogue and all-sky catalogs at other wavelengths to better understand the different physical processes which lead to the emission at different wavelengths.

Based on observations by Bailer-Jones et al. (2018) who propose a close fly-by of the K-type star Gliese 710 in approximately 1.36 Myr we investigate the immediate influence of the stellar passage on trajectories of Oort cloud objects. Using a newly developed GPU-based N-body code (Zimmermann (2021)) we study the motion of 3.6 million testparticles in the outer Solar system where the comets are distributed in three different “layers” around the Sun and the 4 giant planets. We study the immediate influence of Gliese 710 at three passage distances of 12000, 4300, and 1200 au. Additionally, different inclinations of the approaching star are considered. Depending on the passage distance a small number of comets (mainly from the disk and flared disk) is scattered into the observable region (< 5 au) around the Sun. In addition, a huge number of comets (mainly the ones directly in the path of the passing star) shows significant changes of their perihelia. But, they will enter the inner Solar system a long time after the stellar fly-by depending on their dynamical evolution.

This article highlights the successes of the high resolution astrometric VLBI observations used for measuring proper motion of galaxies in the Local group. The required, high accuracies, often in the μ as yr−1 regime, are only attainable through the use of the phase-referencing technique. These require either a compact radio source (AGN) or strong maser emission in the target galaxy and, additionally, some compact extra-galactic radio sources (quasars) to serve as ideal background reference source. The derived proper motions can lead to lower limits on the orbital lower estimates to the mass of the host galaxy, promise a new handle on dynamical models of interacting galaxy systems and offer insights on the spatial distribution of dark matter in the near universe.

The astrophysics of Active Galactic Nuclei (AGN) is one of the long outstanding issues in searches among the scientific communities raised with diverse perspectives like nebula, quasars, etc some decades ago. Currently, this exotic system is at least understood as the center of an active galaxy. Thus, the consensus of this recent theory has opened up a number of research issues for the progress of astrophysical science including how the hosting galaxy evolves with the AGN, how matter and energy flow towards and outwards, etc. Moreover, most of the AGNs possess Supermassive Black Holes (SMBHs) and accrete matter at a very high rate as current observations report. Consequently, both observations of electromagnetic (EM) spectrum and Gravity Waves (GWs) will considered to provide complementary information about the AGNs and the roles in their environments including black holes in their centers, outflow and inflow of matter-energy. Interested with this background rationale, we study the mechanisms of AGN interaction with its environment and flow of relativistic jets where General Relativistic (GR) Magneto-Hydrodynamic (MHD) equations are being considered. The solutions of the field equations are treated with a metric that involves charged systems for the possible relativistic jets including accretions. Then, numerical data is being generated using the latest version Mathematic software. Finally, the theoretical data is being compared with that of observation for validation of the model.

3C 294 is a powerful FR II type radio galaxy at z = 1.786. Due to its proximity of a bright star, it has been subject to several adaptive optics supported imaging studies. The system shows a clumpy structure indicative of a merging system. There is even tentative evidence that 3C 294 hosts a dual AGN. In order to distinguish between the various scenarios for 3C 294 we performed deep high-resolution adaptive optics imaging and optical spectroscopy of 3C 294 with the Large Binocular Telescope. We resolve the 3C 294 system in three distinct components separated by a few tenths of an arcsecond. One of them is compact, the other two are extended. The nature of the latter is unclear. They could be a single galaxy with an internal dust absorption feature, a galaxy merger, or two galaxies at different redshifts. We can now uniquely associate the radio source of 3c 294 with one of the extended components. Based on our spectroscopy, we determine a slightly different redshift of z = 1.784. We find, however, in addition a single emission line at a wavelength of 6745 AA, which might be identified with Lyα at z = 4.56. It thus appears unlikely that 3C294 hosts a dual AGN; it might rather be a pair of AGNs with very small projected separation.

The angular resolution and the sensitivity of a parabolic dish telescope increase with the diameter of its aperture at a given frequency. This implies that as the telescope gets larger, its resolution becomes better. However, constructing telescopes of ever increasing size is prohibitive for both technical and financial reasons. This problem is solved by using an interferometer which consists of two or more separate telescopes that combine their signals offering a resolution equivalent to the largest separation distance between the telescopes. In this work, the electric field variations from two telescopes will be obtained. The voltage signals from the two telescopes will be coherently combined in order to derive the structure of the target source of radio emission. This combination will be done by a cross-correlator, which multiplies and averages the voltage outputs V1 and V2 of the two dishes. A major challenge to be addressed in this work is to design an instrument capable of making professional-type radio astronomy measurement in a local interference environment. In this regard, the investigative part of this work will verify whether it is possible to achieve a high sensitivity enough to detect some cosmic sources where the presence of man-made interference and cost adversely influences the system. The design of an interferometer will be presented and implemented. It may also serve as a demonstrator for engineering students to gain a working knowledge of radio interferometry.

We revisit the problem of the existence of KAM tori in extrasolar planetary systems. Specifically, we consider the υ Andromedæ system, by modelling it with a three-body problem. This preliminary study allows us to introduce a natural way to evaluate the robustness of the planetary orbits, which can be very easily implemented in numerical explorations. We apply our criterion to the problem of the choice of a suitable orbital configuration which exhibits strong stability properties and is compatible with the observational data that are available for the υ Andromedæ system itself.

We explore the intrinsic jet opening angle (IJOA) of blazars, from the literature, we found that the blazar number density peaks around 0.5° of IJOA and declines quickly with increasing IJOA for flat spectrum radio quasars (FSRQs), while the number density has double peaks around 0.3° and 2.0° of IJOA for BL Lacs. We assume that the black hole accretion-produced jet may have the smaller IJOA (for its larger linear scale of launch region), and the BH spin-produced jet may have the larger IJOA (for its smaller launch region), such that the FSRQs are accretion dominated for their single peaked small IJOA, while the BL Lacs are either accretion or BH spin dominated for their double peaked IJOA.

We present a sample of nearly 650 widely separated double white dwarf binaries found using Gaia DR2 astrometry. We derive preliminary total ages for each white dwarf in our sample using Gaia photometry and compare the total ages of both components of each binary in our sample. We find agreement within 3 sigma between the two ages ∼85% of the time with median age uncertainties of ∼3.5 Gyr depending on which initial-final mass relation is used. When a subsample with the most precise ages is used, the agreement within 3 sigma drops to ∼70% with median age uncertainties of 300-600 Myr.

The Laplace resonance is a configuration that involves the commensurability between the mean motions of three small bodies revolving around a massive central one. This resonance was first observed in the case of the three inner Galilean satellites, Io, Europa, and Ganymede. In this work the Laplace resonance is generalised by considering a system of three satellites orbiting a planet that are involved in mean motion resonances. These Laplace-like resonances are classified in three categories: first-order (2:1&2:1, 3:2&3:2, 2:1&3:2), second-order (3:1&3:1) and mixed-order resonances (2:1&3:1). In order to study the dynamics of the system we implement a model that includes the gravitational interaction with the central body, the mutual gravitational interactions of the satellites, the effects due to the oblateness of the central body and the secular interaction of a fourth satellite and a distant star. Along with these contributions we include the tidal interaction between the central body and the innermost satellite. We study the survival of the Laplace-like resonances and the evolution of the orbital elements of the satellites under the tidal effects. Moreover, we study the possibility of capture into resonance of the fourth satellite.

The presence of a super massive BH in almost all galaxies in the Universe is an accepted paradigm in astronomy. How these BHs form and how they co-evolve with the host galaxy is one of the most intriguing unanswered problems in modern Cosmology and of extreme relevance to understand the issue of galaxy formation. Clustering measurements can powerfully test theoretical model predictions of BH triggering scenarios and put constraints on the typical environment where AGN live in, through the connection with their host dark matter halos. In this talk, I will present some recent results on the AGN clustering dependence on host galaxy properties, such as galaxy stellar mass, star formation rate and specific BH accretion rate, based on X-ray selected Chandra COSMOS Legacy Type 2 AGN. We found no significant AGN clustering dependence on galaxy stellar mass and specif BHAR for Type 2 COSMOS AGN at mean z ∼ 1.1, with a stellar - halo mass relation flatter than predicted for non active galaxies in the Mstar range probed by our sample. We also observed a negative clustering dependence on SFR, with AGN hosting halo mass increasing with decreasing SFR. Mock catalogs of active galaxies in hosting dark matter halos with logMh[Msun] > 12.5, matched to have the same X-ray luminosity, stellar mass and BHAR of COSMOS AGN predict the observed Mstar - Mh, BHAR - Mh and SFR-Mh relations, at z ∼ 1.

The J-PAS survey will soon start observing thousands of square degrees of the Northern Sky with its unique set of 56 narrow band filters covering the entire optical wavelength range, providing, effectively, a low resolution spectra for every object detected. Active galaxies and quasars, thanks to their strong emission lines, can be easily identified and characterized with J-PAS data. A variety of studies can be performed, from IFU-like analysis of local AGN, to clustering of high-z quasars. We also expect to be able to extract intrinsic physical quasar properties from the J-PAS pseudo-spectra, including continuum slope and emission line luminosities. Here we show the first attempts of using the QSFit software package to derive the properties for 22 quasars at 0.8 < z < 2 observed by the miniJPAS survey, the first deg2 of J-PAS data obtained with an interim camera. Results are compared with the ones obtained by applying the same software to SDSS quasar spectra.