The Age, Metallicity and Alpha-Element Abundance of Galactic Globular Clusters from Single Stellar Population Models

Establishing the reliability with which stellar population parameters can be measured is vital to extragalactic astronomy. Galactic GCs provide an excellent medium in which to test the consistency of Single Stellar Population (SSP) models as they should be our best analogue to a homogeneous (single) stellar population. Here we present age, metallicity and $\alpha$-element abundance measurements for 48 Galactic globular clusters (GCs) as determined from integrated spectra using Lick indices and SSP models from Thomas, Maraston & Korn, Lee & Worthey and Vazdekis et al. By comparing our new measurements to independent determinations we are able to assess the ability of these SSPs to derive consistent results -- a key requirement before application to heterogeneous stellar populations like galaxies. We find that metallicity determinations are extremely robust, showing good agreement for all models examined here, including a range of enhancement methods. Ages and $\alpha$-element abundances are accurate for a subset of our models, with the caveat that the range of these parameters in Galactic GCs is limited. We are able to show that the application of published Lick index response functions to models with fixed abundance ratios allows us to measure reasonable $\alpha$-element abundances from a variety of models. We also examine the age-metallicity and [$\alpha$/Fe]-metallicity relations predicted by SSP models, and characterise the possible effects of varied model horizontal branch morphology on our overall results.Comment: 22 pages, 19 figures, accepted for publication in MNRA

The #MeToo Movement and Social Dominance Orientation

Social Dominance Orientation (SDO) is a measurement of an individual\u27s desire for the current social hierarchy to be maintained (Sidanius & Pratto, 1994). SDO has long been considered relatively stable, and men have been shown to exhibit higher SDO than women on average. However, recent research suggests that men\u27s SDO scores may increase in response to an outgroup threat (Sugiura et al., 2017). The current study aimed to use the #MeToo Movement as an outgroup threat to investigate the effect of a modern real-world event on SDO scores in men compared to women. Modified news articles covering the #MeToo Movement were used to prime the participants with outgroup threat. Participants read the articles and responded to the SDO7 Likert-Type scale to measure SDO. A 2 (Control vs #MeToo) x 2 (Men vs Women) between-subjects ANOVA was used to analyze the data. We predicted that perceived threat priming by the #MeToo Movement articles would lead to enhanced SDO in male participants. The results were considered inconclusive due to a low representation of men in the sample and low statistical power, but this novel area of research has much potential

Gifts to Minors

Gifts to Minor

Imaging of the protoelliptical NGC 1700 and its globular cluster system

An excellent candidate for a young elliptical, or `protoelliptical' galaxy is NGC 1700. Here we present new B, V and I band imaging using the Keck telescope and reanalyse existing V and I band images from the Hubble Space Telescope. After subtracting a model of the galaxy from the Keck images NGC 1700 reveals two symmetric tidal tail-like structures. If this interpretation is correct, it suggests a past merger event involving two spiral galaxies. These tails are largely responsible for the `boxiness' of the galaxy isophotes observed at a radius of about 13 kpc. We also show that the B-I colour distribution of the globular cluster system is bimodal. The mean colour of the blue population is consistent with those of old Galactic globular clusters. Relative to this old, metal poor population, we find that the red population is younger and more metal rich. This young population has a similar age and metallicity as that inferred for the central stars, suggesting that they are both associated with an episode of star formation triggered by the merger that may have formed the galaxy. Although possessing large errors, we find that the majority of the age estimates of NGC 1700 are reasonably consistent and we adopt a `best estimate' for the age of 3.0 +/-1.0 Gyr. This relatively young age places NGC 1700 within the age range where there is a notable lack of obvious candidates for protoellipticals. The total globular cluster specific frequency is rather low for a typical elliptical, even after taking into account fading of the galaxy over the next 10 Gyr. We speculate that NGC 1700 will eventually form a relatively `globular cluster poor' elliptical galaxy.Comment: 15 pages, 15 figures, accepted for publication in MNRA

Some Aspects of New CDM Models and CDM Detection Methods

We briefly review some recent Cold Dark Matter (CDM) models. Our main focus are charge symmetric models of WIMPs which are not the standard SUSY LSP's (Lightest Supersymmetric Partners). We indicate which experiments are most sensitive to certain aspects of the models. In particular we discuss the manifestations of the new models in neutrino telescopes and other set-ups. We also discuss some direct detection experiments and comment on measuring the direction of recoil ions--which is correlated with the direction of the incoming WIMP. This could yield daily variations providing along with the annual modulation signatures for CDM.Comment: 14 page

The mass-metallicity gradient relation of early-type galaxies

We present a newly observed relation between galaxy mass and radial metallicity gradients of early-type galaxies. Our sample of 51 early-type galaxies encompasses a comprehensive mass range from dwarf to brightest cluster galaxies. The metallicity gradients are measured out to one effective radius by comparing nearly all of the Lick absorption-line indices to recent models of single stellar populations. The relation shows very different behaviour at low and high masses, with a sharp transition being seen at a mass of ~ 3.5 x 10^10 M_sun (velocity dispersion of ~140 km/s, M_B ~ -19). Low-mass galaxies form a tight relation with mass, such that metallicity gradients become shallower with decreasing mass and positive at the very low-mass end. Above the mass transition point several massive galaxies have steeper gradients, but a clear downturn is visible marked by a broad scatter. The results are interpreted in comparison with competing model predictions. We find that an early star-forming collapse could have acted as the main mechanism for the formation of low-mass galaxies, with star formation efficiency increasing with galactic mass. The high-mass downturn could be a consequence of merging and the observed larger scatter a natural result of different merger properties. These results suggest that galaxies above the mass threshold of ~ 3.5 x 10^10 M_sun might have formed initially by mergers of gas-rich disc galaxies and then subsequently evolved via dry merger events. The varying efficiency of the dissipative merger-induced starburst and feedback processes have shaped the radial metallicity gradients in these high-mass systems.Comment: 5 pageg, 3 figures, accepted by ApJ Lette

Mindfulness-Based Stress Reduction in the Treatment of Adults with Autism Spectrum Disorder : a Systematic Review of Interventional Studies

Funding This review did not receive any direct external funding. The review was completed in partial fulfillment of the MBBS programme by one author, which is funded by the Student Awards Agency for Scotland (SAAS). SAAS was not involved in the review.Peer reviewedPublisher PD