G2C2-III: Structural parameters for Galactic globular clusters in SDSS passbands

We use our Galactic Globular Cluster Catalog (G2C2) photometry for 111 Galactic globular clusters (GC) in g and z, as well as r and i photometry for a subset of 60 GCs and u photometry for 22 GCs, to determine the structural parameters assuming King (1962) models. In general, the resulting core radii are in good comparison with the current literature values. However, our half-light radii are slightly lower than the literature. The concentrations (and therefore also the tidal radii) are poorly constrained mostly because of the limited radial extent of our imaging. Therefore, we extensively discuss the effects of a limited field-of-view on the derived parameters using mosaicked SDSS data, which do not suffer from this restriction. We also illustrate how red giant branch (RGB) stars in cluster cores can stochastically induce artificial peaks in the surface brightness profiles. The issues related to these bright stars are scrutinised based on both our photometry and simulated clusters. We also examine colour gradients and find that the strongest central colour gradients are caused by central RGB stars and thus not representative for the cluster light or colour distribution. We recover the known relation between the half-light radius and the Galactocentric distance in the g-band, but find a lower slope for redder filters. We did not find a correlation between the scatter on this relation and other cluster properties. We find tentative evidence for a correlation between the half-light radii and the [Fe/H], with metal-poor GCs being larger than metal-rich GCs. However, we conclude that this trend is caused by the position of the clusters in the Galaxy, with metal-rich clusters being more centrally located.Comment: 17 pages, 23 figures, 3 tables. Accepted to MNRAS. The online appendix includes the structural parameters and the SB profile fits for all the sample cluster

Looking Under a Better Lamppost: MeV-scale Dark Matter Candidates

The era of precision cosmology has revealed that about 85% of the matter in the universe is dark matter. Two well-motivated candidates are weakly interacting massive particles (WIMPs) and weakly interacting sub-eV particles (WISPs) (e.g. axions). Both WIMPs and WISPs possess distinct {\gamma}-ray signatures. Over the last decade, data taken between 50 MeV to >300 GeV by the Fermi Large Area Telescope (Fermi-LAT) have provided stringent constraints on both classes of dark matter models. Thus far, there are no conclusive detections. However, there is an intriguing {\gamma}-ray excess associated with the Galactic center that could be explained by WIMP annihilation. At lower energies, the poor angular resolution of the Fermi-LAT makes source identification challenging, inhibiting our ability to more sensitively probe both the Galactic center excess, as well as lower-mass WIMP and WISP models. Additionally, targeted WISP searches (e.g., those probing supernovae and blazars) would greatly benefit from enhanced energy resolution and polarization measurements in the MeV range. To address these issues, a new telescope that is optimized for MeV observations is needed. Such an instrument would allow us to explore new areas of dark matter parameter space and provide unprecedented access to its particle nature.Comment: White paper submitted to Astro2020 (Astronomy and Astrophysics Decadal Survey) on behalf of a subset of the AMEGO tea

To 'Vape' or Smoke? A Discrete Choice Experiment among Adult Smokers

A growing share of the United States population uses e-cigarettes. In response, policymakers are considering regulating e-cigarettes, or have already done so, due to concerns regarding e-cigarettes' public health impact. However, there is currently little population-based evidence to inform these regulatory choices. More information is needed on how policy-relevant factors will likely drive smokers' decision to use e-cigarettes. To provide this information we conduct an online survey and discrete choice experiment to investigate how adult tobacco cigarette smokers' demand for cigarette type varies by four policy-relevant attributes: 1) whether e-cigarettes are considered healthier than tobacco cigarettes, 2) the effectiveness of e-cigarettes as a cessation device, 3) bans on use in public places such as bars and restaurants, and 4) price. Overall, we find that the demand for e-cigarettes is motivated more by smokers' health concerns than by the desire to avoid smoking bans or higher prices. However, results from latent class models reveal three distinct groups of smokers, those who prefer: tobacco cigarettes, e-cigarettes, and using both products. Each group responds differently to the cigarette attributes suggesting that policies will have different impacts across the groups

Current Concepts and Trends in Human-Automation Interaction

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.The purpose of this panel was to provide a general overview and discussion of some of the most current and controversial concepts and trends in human-automation interaction. The panel was composed of eight researchers and practitioners. The panelists are well-known experts in the area and offered differing views on a variety of different human-automation topics. The range of concepts and trends discussed in this panel include: general taxonomies regarding stages and levels of automation and function allocation, individualized adaptive automation, automation-induced complacency, economic rationality and the use of automation, the potential utility of false alarms, the influence of different types of false alarms on trust and reliance, and a system-wide theory of trust in multiple automated aids

G2C2 II: Integrated colour-metallicity relations for Galactic Globular Clusters in SDSS passbands

We use our integrated SDSS photometry for 96 globular clusters in $g$ and $z$, as well as $r$ and $i$ photometry for a subset of 56 clusters, to derive the integrated colour-metallicity relation (CMR) for Galactic globular clusters. We compare this relation to previous work, including extragalactic clusters, and examine the influence of age, present-day mass function variations, structural parameters and the morphology of the horizontal branch on the relation. Moreover, we scrutinise the scatter introduced by foreground extinction (including differential reddening) and show that the scatter in the colour-metallicity relation can be significantly reduced combining two reddening laws from the literature. In all CMRs we find some low-reddening young GCs that are offset to the CMR. Most of these outliers are associated with the Sagittarius system. Simulations show that this is due less to age than to a different enrichment history. Finally, we introduce colour-metallicity relations based on the infrared Calcium triplet, which are clearly non-linear when compared to $(g^\prime-i^\prime)$ and $(g^\prime-z^\prime)$ colours.Comment: Accepted for publication in MNRAS. 17 pages, 18 figure