Local-Group tests of dark-matter Concordance Cosmology: Towards a new paradigm for structure formation

(abridged) Predictions of the Concordance Cosmological Model (CCM) of the structures in the environment of large spiral galaxies are compared with observed properties of Local Group galaxies. Five new most probably irreconcilable problems are uncovered. However, the Local Group properties provide hints that may lead to a solution of the above problems The DoS and bulge--satellite correlation suggest that dissipational events forming bulges are related to the processes forming phase-space correlated satellite populations. Such events are well known to occur since in galaxy encounters energy and angular momentum are expelled in the form of tidal tails, which can fragment to form populations of tidal-dwarf galaxies (TDGs) and associated star clusters. If Local Group satellite galaxies are to be interpreted as TDGs then the sub-structure predictions of CCM are internally in conflict. All findings thus suggest that the CCM does not account for the Local Group observations and that therefore existing as well as new viable alternatives have to be further explored. These are discussed and natural solutions for the above problems emerge.Comment: A and A, in press, 25 pages, 9 figures; new version contains minor text adjustments for conformity with the published version and additional minor changes resulting from reader's feedback. The speculation on a dark force has been added. Also, the Fritz Zwicky Paradox is now included to agree with the published versio

Mass Loss From Evolved Stars in Elliptical Galaxies

Most of the X-ray emitting gas in early-type galaxies probably originates from red giant mass loss and here we model the interaction between this stellar mass loss and the hot ambient medium. Using two-dimensional hydrodynamic simulations, we adopt a temperature for the ambient medium of 3E6 K along with a range of ambient densities and stellar velocities. When the stellar velocity is supersonic relative to the ambient medium, a bow shock occurs, along with a shock driven into the stellar ejecta, which heats only a fraction of the gas. Behind the bow shock, a cool wake develops but the fast flow of the hot medium causes Kelvin-Helmholtz instabilities to grow and these fingers are shocked and heated (without radiative cooling). Along with the mixing of this wake material with the hot medium, most of the stellar ejecta is heated to approximately the temperature of the hot ambient medium within 2 pc of the star. With the addition of radiative cooling, some wake material remains cool (< 1E5 K), accounting for up to 25% of the stellar mass loss. Less cooled gas survives when the ambient density is lower or when the stellar velocity is higher than in our reference case. These results suggest that some cooled gas should be present in the inner part of early-type galaxies that have a hot ambient medium. These calculations may explain the observed distributed optical emission line gas as well as the presence of dust in early-type galaxies.Comment: 57 pages, which includes 27 figures; ApJ, in press. A version with full-resolution figures can be found at http://www.astro.lsa.umich.edu/~jbregman/public/ms.ps.g

SATCON2: Executive Summary

About twenty years ago, rapid advances in technology led to the viability of lightemitting diodes (LEDs) as outdoor lighting. With compelling operational and economic reasons to make the shift from legacy gas-discharge systems, communities around the world began installing white LEDs as their lighting of choice. In time, the side effects of the vastly increased sky glow and blue-rich spectral distribution of white LEDs became apparent, negatively impacting not only ground-based professional and amateur astronomy but also casual appreciation of the sky, flora and fauna, and human health. Today, we are in the initial years of an analogous watershed moment, this time not on the ground but in space. The rapid development of efficient and in one case reusable rockets by private-sector companies has made Earth orbit no longer the exclusive realm of national agencies like NASA, and a steadily increasing number of entities is now launching both people and hardware into space. The result is exponential growth in the density and variety of satellites at a wide range of altitudes. As the glowing nighttime landscape on Earth has been transformed over the past two decades, so the sky is now being similarly transformed. It is incumbent on all who use space and the night sky as a resource — professional and amateur astronomers, satellite operators, policymakers, environmentalists, people who observe the night sky and who preserve their culture in stories in the stars, and more — to consider the myriad impacts on humanity of the industrialization of space and to establish a shared vision for the use of space that supports and respects all its users. Many efforts today to address the impact of rapidly growing light domes over cities and towns are reactive to already-deployed networks of white LEDs. In the realm of low-Earth orbit (LEO), there is a window of opportunity — albeit narrow and closing — to address the impact of thousands of new satellites proactively. The SATCON workshops are meant to set the foundation for this work

Hot gas flows on global and nuclear galactic scales

Since its discovery as an X-ray source with the Einstein Observatory, the hot X-ray emitting interstellar medium of early-type galaxies has been studied intensively, with observations of improving quality, and with extensive modeling by means of numerical simulations. The main features of the hot gas evolution are outlined here, focussing on the mass and energy input rates, the relationship between the hot gas flow and the main properties characterizing its host galaxy, the flow behavior on the nuclear and global galactic scales, and the sensitivity of the flow to the shape of the stellar mass distribution and the mean rotation velocity of the stars.Comment: 22 pages. Abbreviated version of chapter 2 of the book "Hot Interstellar Matter in Elliptical Galaxies", Springer 201

The magnetic and metallic degenerate G77-50

The definitive version can be found at: http://onlinelibrary.wiley.com/ Copyright Royal Astronomical SocietyAn accumulation of multi-epoch, high-resolution optical spectra reveal that the nearby star G77-50 is a very cool DAZ white dwarf externally polluted by Mg, Fe, Al, Ca and possibly Na, Cr, Mn. The metallic and hydrogen absorption features all exhibit multiple components consistent with Zeeman splitting in a B approximate to 120 kG magnetic field. Ultraviolet through infrared photometry combined with trigonometric parallaxes yield T-eff = 5310 K, M = 0.60 M-circle dot and a cooling age of 5.2 Gyr. The space velocity of the white dwarf suggests possible membership in the Galactic thick disc, consistent with an estimated total age of 8.6 Gyr. G77-50 is spectrally similar to G165-7 and LHS 2534; these three cool white dwarfs comprise a small group exhibiting both metals and magnetism. The photospheric metals indicate accretion of rocky debris similar to that contained in asteroids, but the cooling age implies that a remnant planetary system should be stable. A possibility for G77-50 and similarly old, polluted white dwarfs is a recent stellar encounter that dynamically rejuvenated the system from the outside-in. Metal abundance measurements for these cooler white dwarfs have the potential to distinguish material originating in outer region planetesimals injected via fly-by. If common envelope evolution can generate magnetic fields in white dwarfs, then G77-50 and its classmates may have cannibalized an inner giant planet during prior evolution, with their metals originating in terrestrial bodies formed further out. Although speculative, this scenario can be ruled out if terrestrial planet formation is prohibited in systems where a giant planet has migrated to the inner region nominally engulfed during the post-main sequence.Peer reviewedFinal Accepted Versio

Surface Modification of Biodegradable Microparticles with the Novel Host-Derived Immunostimulant CPDI-02 Significantly Increases Short-Term and Long-Term Mucosal and Systemic Antibodies against Encapsulated Protein Antigen in Young Na&iuml;ve Mice after Respiratory Immunization

Generating long-lived mucosal and systemic antibodies through respiratory immunization with protective antigens encapsulated in nanoscale biodegradable particles could potentially decrease or eliminate the incidence of many infectious diseases, but requires the incorporation of a suitable mucosal immunostimulant. We previously found that respiratory immunization with a model protein antigen (LPS-free OVA) encapsulated in PLGA 50:50 nanoparticles (~380 nm diameter) surface-modified with complement peptide-derived immunostimulant 02 (CPDI-02; formerly EP67) through 2 kDa PEG linkers increases mucosal and systemic OVA-specific memory T-cells with long-lived surface phenotypes in young, na&iuml;ve female C57BL/6 mice. Here, we determined if respiratory immunization with LPS-free OVA encapsulated in similar PLGA 50:50 microparticles (~1 &mu;m diameter) surface-modified with CPDI-02 (CPDI-02-MP) increases long-term OVA-specific mucosal and systemic antibodies. We found that, compared to MP surface-modified with inactive, scrambled scCPDI-02 (scCPDI-02-MP), intranasal administration of CPDI-02-MP in 50 &mu;L sterile PBS greatly increased titers of short-term (14 days post-immunization) and long-term (90 days post-immunization) antibodies against encapsulated LPS-free OVA in nasal lavage fluids, bronchoalveolar lavage fluids, and sera of young, na&iuml;ve female C57BL/6 mice with minimal lung inflammation. Thus, surface modification of ~1 &mu;m biodegradable microparticles with CPDI-02 is likely to increase long-term mucosal and systemic antibodies against encapsulated protein antigen after respiratory and possibly other routes of mucosal immunization

Targeted Amino Acid Substitution Overcomes Scale-Up Challenges with the Human C5a-Derived Decapeptide Immunostimulant EP67.

EP67 is a second-generation, human C5a-derived decapeptide agonist of C5a receptor 1 (C5aR1/CD88) that selectively activates mononuclear phagocytes over neutrophils to potentiate protective innate and adaptive immune responses while potentially minimizing neutrophil-mediated toxicity. Pro7 and N-methyl-Leu8 (Me-Leu8) amino acid residues within EP67 likely induce backbone structural changes that increase potency and selective activation of mononuclear phagocytes over neutrophils versus first-generation EP54. The low coupling efficiency between Pro7 and Me-Leu8 and challenging purification by HPLC, however, greatly increase scale-up costs of EP67 for clinical use. Thus, the goal of this study was to determine whether replacing Pro7 and/or Me-Leu8 with large-scale amenable amino acid residues predicted to induce similar structural changes (cyclohexylalanine7 and/or leucine8) sufficiently preserves EP67 activity in primary human mononuclear phagocytes and neutrophils. We found that EP67 analogues had similar potency, efficacy, and selective activation of mononuclear phagocytes over neutrophils. Thus, replacing Pro7 and/or Me-Leu8 with large-scale amenable amino acid residues predicted to induce similar structural changes is a suitable strategy to overcome scale-up challenges with EP67