Extremely massive disc galaxies in the nearby Universe form through gas-rich minor mergers

© 2022 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. an article which has been published in final form at https://doi.org/10.1093/mnras/stac058In our hierarchical structure-formation paradigm, the observed morphological evolution of massive galaxies -- from rotationally-supported discs to dispersion-dominated spheroids -- is largely explained via galaxy merging. However, since mergers are likely to destroy discs, and the most massive galaxies have the richest merger histories, it is surprising that any discs exist at all at the highest stellar masses. Recent theoretical work by our group has used a cosmological, hydrodynamical simulation to suggest that extremely massive (M* > 10^11.4 MSun) discs form primarily via minor mergers between spheroids and gas-rich satellites, which create new rotational stellar components and leave discs as remnants. Here, we use UV-optical and HI data of massive galaxies, from the SDSS, GALEX, DECaLS and ALFALFA surveys, to test these theoretical predictions. Observed massive discs account for ~13% of massive galaxies, in good agreement with theory (~11%). ~64% of the observed massive discs exhibit tidal features, which are likely to indicate recent minor mergers, in the deep DECaLS images (compared to ~60% in their simulated counterparts). The incidence of these features is at least four times higher than in low-mass discs, suggesting that, as predicted, minor mergers play a significant (and outsized) role in the formation of these systems. The empirical star-formation rates agree well with theoretical predictions and, for a small galaxy sample with HI detections, the HI masses and fractions are consistent with the range predicted by the simulation. The good agreement between theory and observations indicates that extremely massive discs are indeed remnants of recent minor mergers between spheroids and gas-rich satellites.Peer reviewedFinal Accepted Versio

The health of women and girls determines the health and well-being of our modern world: A White Paper From the International Council on Women's Health Issues

The International Council on Women's Health Issues (ICOWHI) is an international nonprofit association dedicated to the goal of promoting health, health care, and well-being of women and girls throughout the world through participation, empowerment, advocacy, education, and research. We are a multidisciplinary network of women's health providers, planners, and advocates from all over the globe. We constitute an international professional and lay network of those committed to improving women and girl's health and quality of life. This document provides a description of our organization mission, vision, and commitment to improving the health and well-being of women and girls globally

Children’s Stories Supporting the Development of Critical Literacy and Intercultural Understanding

This chapter examines the possibilities of applying children’s storybooks in supporting the development of critical literacy as well as intercultural understanding. Valuing and supporting children’s reading is known to provide understanding and empathy towards other human beings. The chapter focuses on theoretical notions related to promoting critical literacies through children’s storybooks, but also includes practical examples of utilizing multicultural children’s stories. The chapter introduces different strategies that parents and teachers can use to support the development of critical literacy, including critical thinking and understanding multiple perspectives. Focus is especially on young children, because they already are capable of moving beyond what is in front of them on the page. Since children’s storybooks offer possibilities for readers to question implicit assumptions about self and others, books can support readers in becoming more culturally aware and sensitive. Consequently, reading storybooks can affect children’s intercultural understanding, and the role of storybooks in children’s moral development – both shaping and changing attitudes – should be seen as transformative.Peer reviewe

Preparing for low surface brightness science with the Vera C. Rubin Observatory:Characterization of tidal features from mock images

Tidal features in the outskirts of galaxies yield unique information about their past interactions and are a key prediction of the hierarchical structure formation paradigm. The Vera C. Rubin Observatory is poised to deliver deep observations for potentially millions of objects with visible tidal features, but the inference of galaxy interaction histories from such features is not straightforward. Utilizing automated techniques and human visual classification in conjunction with realistic mock images produced using the NewHorizon cosmological simulation, we investigate the nature, frequency, and visibility of tidal features and debris across a range of environments and stellar masses. In our simulated sample, around 80 per cent of the flux in the tidal features around Milky Way or greater mass galaxies is detected at the 10-yr depth of the Legacy Survey of Space and Time (30-31 mag arcsec-2), falling to 60 per cent assuming a shallower final depth of 29.5 mag arcsec-2. The fraction of total flux found in tidal features increases towards higher masses, rising to 10 per cent for the most massive objects in our sample (M* ∼1011.5 M⊙). When observed at sufficient depth, such objects frequently exhibit many distinct tidal features with complex shapes. The interpretation and characterization of such features varies significantly with image depth and object orientation, introducing significant biases in their classification. Assuming the data reduction pipeline is properly optimized, we expect the Rubin Observatory to be capable of recovering much of the flux found in the outskirts of Milky Way mass galaxies, even at intermediate redshifts (z < 0.2)

Preparing for low surface brightness science with the Vera C. Rubin Observatory: characterisation of tidal features from mock images

Tidal features in the outskirts of galaxies yield unique information about their past interactions and are a key prediction of the hierarchical structure formation paradigm. The Vera C. Rubin Observatory is poised to deliver deep observations for potentially of millions of objects with visible tidal features, but the inference of galaxy interaction histories from such features is not straightforward. Utilising automated techniques and human visual classification in conjunction with realistic mock images produced using the NEWHORIZON cosmological simulation, we investigate the nature, frequency and visibility of tidal features and debris across a range of environments and stellar masses. In our simulated sample, around 80 per cent of the flux in the tidal features around Milky Way or greater mass galaxies is detected at the 10-year depth of the Legacy Survey of Space and Time (30-31 mag / sq. arcsec), falling to 60 per cent assuming a shallower final depth of 29.5 mag / sq. arcsec. The fraction of total flux found in tidal features increases towards higher masses, rising to 10 per cent for the most massive objects in our sample (M*~10^{11.5} Msun). When observed at sufficient depth, such objects frequently exhibit many distinct tidal features with complex shapes. The interpretation and characterisation of such features varies significantly with image depth and object orientation, introducing significant biases in their classification. Assuming the data reduction pipeline is properly optimised, we expect the Rubin Observatory to be capable of recovering much of the flux found in the outskirts of Milky Way mass galaxies, even at intermediate redshifts (z<0.2)

Cyclodextrin containing nano- and microgels for uptake and release of chemical agents

This thesis deals with the preparation and characterization of novel functional polymeric nano- and microgels using cyclodextrin (CD) as multifunctional cross-linker and supramolecular complexation domain for the uptake and release of potential chemical agents. The incorporation of natural and vinyl functionalized alpha-, beta- and gamma-CDs were studied in different polymerization reactions with different types of monomers for the preparation of stable nano- and microgels with specific properties. First, reactive alpha-, beta-, and gamma-CD acrylates (CD-As) and CD methacrylates (CD-MAs) were synthesized with an average amount of vinyl bonds per CD molecule of 2, 4, or 6. They were used as cross-linkers to react with acrylate and methacrylate monomers by free radical precipitation polymerization and in addition as complexation unit for the uptake of chemical agents. Hydrophobic CD-MA nanogels based on methylmethacrylate (MMA), aqueous CD-A nanogels based on 2-poly(hydroxyethyl methacrylate) (HEMA) and thermosensitive nanogels based on CD-A and N-vinylcaprolactam (VCL) were prepared. The preparation of CD containing nano- and microgels showed that the particle size (Rh=20-400 nm), particle growth and the formation of stable nanoparticle dispersions in organic as well as in aqueous solutions are strongly influenced by the use of CD-A and CD-MA. Furthermore, nanogels with a high CD content were prepared by cross-linking of non-functionalized natural CD with the reactive isocyanate (NCO)-terminated star-shaped poly(ethylene oxide-stat-propylene oxide) (sP(EO-stat-PO)) prepolymer under smooth surfactant-free condensation in water at RT. Optimization of the reaction parameters yielded in ultrafine nanogels (Rh=25-150 nm) with a maximum content of 60 wt.-% active CD. The complexation capacity and application possibilities of CD containing nano- and microgels were investigated with regard to the uptake and release properties of potential organic guest molecules like sensitive dyes (phenolphthalein, nile red), antimicrobial agents (chlorhexidine), insecticides (permethrin) and pharmaceutical active ingredients (ibuprofen). Results showed that CD units in nanogels have significant influence on the uptake of organic guest molecules. The controlled inclusion complexation of the guests took place in dependence on the CD content and on the ring size using alpha-, beta- and gamma-CDs. The monomer composition and the degree of cross-linking of polymeric nanogel structure had an influence on the uptake as well. The release and stability of the guest molecules in nanogels depend on the external environment. In general, the CD nanogel complexes using hydrophobic guest molecules were stable in water. Slightly water soluble guest molecules were slowly released by changes of the surrounding water concentration. Light sensitive guest molecules could be protected against UV irradiation due to complexation in CD nanogels. Application on different surfaces such as polyester fibers or keratin fibers due to physical self-bonding can be controlled by nanogel concentration in the dispersion and by coating time. Bioassay tests of permethrin and chlorhexidine loaded nanogels treated surfaces showed that the insecticidal and antimicrobial activity of the ingredients did not decrease after complexation in cyclodextrin containing nanogels