Formation and physical properties of central structures in barred galaxies

The evolution of disc galaxies is governed not only by violent and external processes, but also by slow and continuous, internal evolution. One of the main drivers of this secular evolution are bars: these strongly non-axisymmetric stellar structures are present in 2/3 of all massive disc galaxies in the local Universe and have a substantial impact on their evolution. Amongst many other effects, they efficiently facilitate the inflow of gas from the main galaxy disc to their central regions, where this gas settles and eventually new stellar structures, such as nuclear discs, nuclear rings, and inner bars, are built. In this thesis, we aim to better characterise the properties of these central stellar structures and constrain their formation and evolutionary history. To this end, we employ integral-field spectroscopic observations from MUSE, obtained as part of the TIMER survey. The sample consists of 21 barred disc galaxies in the local Universe exhibiting a variety of central structures, and about 100000 science-ready spectra are available for each galaxy. In order to facilitate the exploitation of this massive data set, we develop the sophisticated software framework GIST for the analysis and visualisation of spectroscopic data. Using this tool, we derive stellar kinematics and mean population properties in the central regions of these galaxies at an unprecedented spatial resolution. We find that nuclear discs are characterised by high rotational velocities, low velocity dispersions, and near-circular orbits, while consisting of stellar populations that are significantly younger, more metal-rich, and less [α/Fe] enhanced, as compared to their direct surroundings. These properties of nuclear discs are consistent with the bar-driven formation scenario. Based on our radial population profiles in the nuclear discs, in particular stellar ages decreasing from the galaxy centre to their outer edge, and a correlation between the radii of (gaseous) nuclear rings and the bar length, we propose a new inside-out formation scenario for nuclear discs: in this picture, (stellar) nuclear discs are formed from a series of star-forming nuclear rings that grow in radius as the bar evolves. Combining measurements of both kinematics and stellar population properties, we find only little evidence for the presence of large, classical bulges in these galaxies. Although the galaxy sample is biased towards barred galaxies, the absence of classical bulges in such massive galaxies is surprising. Investigating the stellar population content of the three inner bars in TIMER, we find that these structures are characterised by high metallicities and low [α/Fe] abundances, similar to main bars. Moreover, inner bars exhibit slightly younger stellar ages at their outer ends, an effect known from studies on main bars as orbital age separation. In addition, radial profiles of metallicities and [α/Fe] enhancements are flat along the inner bar major axis, but show significantly steeper slopes along their minor axis, again analogous to previous findings in the context of main bars. These results suggest that inner and main bars are dynamically similar structures that differ only in the spatial scale on which they exist

THE CHALLENGES TO DEVELOPING SMART AGRICULTURAL VILLAGE IN THE INDUSTRIAL REVOLUTION 4.0.: THE CASE OF INDONESIA

Nowadays, rural depopulation is one of the biggest problems in developed and developing countries, especially due to the COVID-19 pandemic. This pandemic impacts various sectors, especially the economic sector. However, the development of the 4.0 Industrial Revolution forced all sectors, including agriculture, to adapt and take advantage of internet-based digital technology by developing smart agriculture. Therefore, the objective of this study is to analyze the development of smart agriculture in rural areas. This study uses a systematic literature review with a TAA approach with secondary data collected from Scopus databases. The downloaded documents will be further analyzed using VOSviewer software to find the clustering. After the coding process by first-order categories, second layer theme, and aggregate dimension, this research found several theoretical concepts about the “Smart Village”. The definition of the ‘smart village’ concept is a combination of smart agriculture and industry 4.0 technology utilized by rural MSMEs to use the information and communication technology integrated into public services and economic activities. There are still many obstacles encountered in the application of ‘smart villages,’ such as the lack of youth participation and the low quality of human resources in the agricultural sector, limited internet network coverage, and the lack of optimal capital support. This research will contribute to the systematic literature review method by purposing filtering criteria of TAA to shade the light of the lack of data accuracy in several leading databases of scholarly impacts. This research also gives a clear direction for further research regarding industry 4.0 and Indonesia's smart agriculture concept application

Kinematical Signatures of Disc Instabilities and Secular Evolution in the MUSE TIMER Survey

The MUSE TIMER Survey has obtained high signal and high spatial resolution integral-field spectroscopy data of the inner $\sim6\times6$ kpc of 21 nearby massive disc galaxies. This allows studies of the stellar kinematics of the central regions of massive disc galaxies that are unprecedented in spatial resolution. We confirm previous predictions from numerical and hydrodynamical simulations of the effects of bars and inner bars on stellar and gaseous kinematics, and also identify box/peanuts via kinematical signatures in mildly and moderately inclined galaxies, including a box/peanut in a face-on inner bar. In 20/21 galaxies we find inner discs and show that their properties are fully consistent with the bar-driven secular evolution picture for their formation. In addition, we show that these inner discs have, in the region where they dominate, larger rotational support than the main galaxy disc, and discuss how their stellar population properties can be used to estimate when in cosmic history the main bar formed. Our results are compared with photometric studies in the context of the nature of galaxy bulges and we show that inner discs are identified in image decompositions as photometric bulges with exponential profiles (i.e., S\'ersic indices near unity).Comment: 4 pages, 5 figures, to appear in Galactic Dynamics in the Era of Large Surveys, M. Valluri & J. A. Sellwood (eds.

Quantum Origins of Molecular Recognition and Olfaction in Drosophila

The standard model for molecular recognition of an odorant is that receptor sites discriminate by molecular geometry as evidenced that two chiral molecules may smell very differently. However, recent studies of isotopically labeled olfactants indicate that there may be a molecular vibration-sensing component to olfactory reception, specifically in the spectral region around 2300 cm$^{-1}$. Here we present a donor-bridge-acceptor model for olfaction which attempts to explain this effect. Our model, based upon accurate quantum chemical calculations of the olfactant (bridge) in its neutral and ionized states, posits that internal modes of the olfactant are excited impulsively during hole transfer from a donor to acceptor site on the receptor, specifically those modes that are resonant with the tunneling gap. By projecting the impulsive force onto the internal modes, we can determine which modes are excited at a given value of the donor-acceptor tunneling gap. Only those modes resonant with the tunneling gap and are impulsively excited will give a significant contribution to the inelastic transfer rate. Using acetophenone as a test case, our model and experiments on D. melanogaster suggest that isotopomers of a given olfactant give rise to different odorant qualities. These results support the notion that inelastic scattering effects play a role in discriminating between isotopomers, but that this is not a general spectroscopic effectComment: 7 pages, 3 figure

Tambora and the Mackerel Year: Phenology and Fisheries During an Extreme Climate Event

Global warming has increased the frequency of extreme climate events, yet responses of biological and human communities are poorly understood, particularly for aquatic ecosystems and fisheries. Retrospective analysis of known outcomes may provide insights into the nature of adaptations and trajectory of subsequent conditions. We consider the 1815 eruption of the Indonesian volcano Tambora and its impact on Gulf of Maine (GoM) coastal and riparian fisheries in 1816. Applying complex adaptive systems theory with historical methods, we analyzed fish export data and contemporary climate records to disclose human and piscine responses to Tambora’s extreme weather at different spatial and temporal scales while also considering sociopolitical influences. Results identified a tipping point in GoM fisheries induced by concatenating social and biological responses to extreme weather. Abnormal daily temperatures selectively affected targeted fish species—alewives, shad, herring, and mackerel—according to their migration and spawning phenologies and temperature tolerances. First to arrive, alewives suffered the worst. Crop failure and incipient famine intensified fishing pressure, especially in heavily settled regions where dams already compromised watersheds. Insufficient alewife runs led fishers to target mackerel, the next species appearing in abundance along the coast; thus, 1816 became the “mackerel year.” Critically, the shift from riparian to marine fisheries persisted and expanded after temperatures moderated and alewives recovered. We conclude that contingent human adaptations to extraordinary weather permanently altered this complex system. Understanding how adaptive responses to extreme events can trigger unintended consequences may advance long-term planning for resilience in an uncertain future

Inside-out formation of nuclear discs and the absence of old central spheroids in barred galaxies of the TIMER survey

The centres of disc galaxies host a variety of structures built via both internal and external processes. In this study, we constrain the formation and evolution of these central structures, in particular, nuclear rings and nuclear discs, by deriving maps of mean stellar ages, metallicities, and [α/Fe] abundances. We use observations obtained with the MUSE integral-field spectrograph for the TIMER sample of 21 massive barred galaxies. Our results indicate that nuclear discs and nuclear rings are part of the same physical component, with nuclear rings constituting the outer edge of nuclear discs. All nuclear discs in the sample are clearly distinguished based on their stellar population properties. As expected in the picture of bar-driven secular evolution, nuclear discs are younger, more metal-rich, and exhibit lower [α/Fe] enhancements, as compared to their immediate surroundings. Moreover, nuclear discs exhibit well-defined radial gradients, with ages and metallicities decreasing, and [α/Fe] abundances increasing with radius out to the nuclear ring. Often, these gradients show no breaks from the edge of the nuclear disc up through the centre, suggesting that these structures extend to the very centres of galaxies. We argue that continuous (stellar) nuclear discs may form from a series of bar-built (initially gas-rich) nuclear rings that expand in their radius as the bar evolves. In this picture, nuclear rings are simply the (often) star-forming outer edge of nuclear discs. Finally, by combining our results with those taken from a accompanying kinematic study, we do not find evidence for the presence of large, dispersion-dominated components in the centres of these galaxies. This could be a result of quiet merger histories, despite the large galaxy masses, or, perhaps, due to high angular momentum and strong feedback processes preventing the formation of these kinematically hot components

Kinematic signatures of nuclear discs and bar-driven secular evolution in nearby galaxies of the MUSE TIMER project

The central regions of disc galaxies hold clues to the processes that dominate their formation and evolution. To exploit this, the TIMER project has obtained high signal-to-noise and spatial resolution integral-field spectroscopy data of the inner few kpc of 21 nearby massive barred galaxies, which allows studies of the stellar kinematics in their central regions with unprecedented spatial resolution. We confirm theoretical predictions of the effects of bars on stellar kinematics and identify box/peanuts through kinematic signatures in mildly and moderately inclined galaxies, finding a lower limit to the fraction of massive barred galaxies with box/peanuts at ∼62%. Further, we provide kinematic evidence of the connection between barlenses, box/peanuts, and bars. We establish the presence of nuclear discs in 19 galaxies and show that their kinematics are characterised by near-circular orbits with low pressure support and that they are fully consistent with the bar-driven secular evolution picture for their formation. In fact, we show that these nuclear discs have, in the region where they dominate, larger rotational support than the underlying main galaxy disc. In addition, we define a kinematic radius for the nuclear discs and show that it relates to bar radius, ellipticity and strength, and bar-to-total ratio. Comparing our results with photometric studies of galaxy bulges, we find that careful, state-of-the-art galaxy image decompositions are generally able to discern nuclear discs from classical bulges if the images employed have high enough physical spatial resolution. In fact, we show that nuclear discs are typically identified in such image decompositions as photometric bulges with (near-)exponential profiles. However, we find that the presence of composite bulges (galaxies hosting both a classical bulge and a nuclear disc) can often be unnoticed in studies based on photometry alone and suggest a more stringent threshold to the Sérsic index to identify galaxies with pure classical bulges