Keck spectroscopy of the faint dwarf elliptical galaxy population in the Perseus Cluster core: mixed stellar populations and a flat luminosity function

We present the result of a photometric and Keck-LRIS spectroscopic study of dwarf galaxies in the core of the Perseus Cluster, down to a magnitude of M_B = -12.5. Spectra were obtained for twenty-three dwarf-galaxy candidates, from which we measure radial velocities and stellar population characteristics from absorption line indices. From radial velocities obtained using these spectra we confirm twelve systems as cluster members, with the remaining eleven as non-members. Using these newly confirmed cluster members, we are able to extend the confirmed colour-magnitude relation for the Perseus Cluster down to M_B = -12.5. We confirm an increase in the scatter about the colour magnitude relationship below M_B = -15.5, but reject the hypothesis that very red dwarfs are cluster members. We measure the faint-end slope of the luminosity function between M_B = -18 and M_B = -12.5, finding alpha = -1.26 \pm 0.06, which is similar to that of the field. This implies that an overabundance of dwarf galaxies does not exist in the core of the Perseus Cluster. By comparing metal and Balmer absorption line indices with alpha-enhanced single stellar population models, we derive ages and metallicities for these newly confirmed cluster members. We find two distinct dwarf elliptical populations: an old, metal poor population with ages ~ 8 Gyr and metallicities [Fe/H] < -0.33, and a young, metal rich population with ages -0.33. Dwarf galaxies in the Perseus Cluster are therefore not a simple homogeneous population, but rather exhibit a range in age and metallicity.Comment: 12 pages, 9 figures. Accepted for publication in MNRA

Inter-agency adult support and protection practice:a realistic evaluation with police, health and social care professionals

Purpose: Collaborative inter-agency working is of paramount importance for the public protection agenda worldwide. The purpose of this paper is to disseminate the findings from a research study on the inter-agency working within adult support and protection (ASP) roles in the police, health and social care.Design/methodology/approach: This realistic evaluation study with two inter-related phases was funded by the Scottish Institute for Policing Research. This paper reports on Phase 1 which identified existing gaps in the implementation of effective inter-agency practice by reviewing the “state of play” in inter-agency collaboration between the police and health and social care professionals. In total, 13 focus groups comprising representatives from Police Scotland (n¼52), Social Care (n¼31) and Health (n¼18), engaged in single profession and mixed profession groups addressing issues including referral and information exchange.Findings: On analysing context-mechanism-outcome (CMO), gaps in joint working were identified and attributed to the professionals’ own understanding of inter-agency working and the expectations of partner agencies. It recommended the need for further research and inter-agency training on public protection. Research limitations/implications – This unique Scottish study successfully identified the inter-agency practices of health, social services and police. By means of a modified realistic evaluation approach, it provides an in-depth understanding of the challenges that professionals face on a day-to-day basis when safeguarding adults and informed strategic recommendations to overcome the barriers to good practices in organisational working. The methods used to determine CMO could benefit other researchers to develop studies exploring the complexities of multi-causal effects of cross-boundary working. The use of the same case study in each focus group helped to neutralise bias. However, the voluntary nature of participation could have resulted in biased perceptions. The limited numbers of health professionals may have resulted in less representation of health sector views.Practical implications: Collaborative inter-agency working is of paramount importance for public protection worldwide. This paper reports on a Scottish study that focussed on the coordinated and integrated practices amongst the police, health and social services’ professionals who support and protect adult members of society at risk of harm.Social implications: Whilst the focus of this study has been on ASP, the conclusions and recommendations are transferable to public protection issues in many other contexts.Originality/value: Studies on the joint-working practices amongst police and health and social services’ professionals who support and protect adult members of society at risk of harm are uncommon. This  study investigated professionals’ perceptions of gaps and concerns pertaining to integrated working by means of a realistic evaluation approach. It recommended the need for further research and inter-agency training on public protection

The effectiveness of physical activity interventions in improving higher education students' mental health : A systematic review

Peer reviewe

The many assembly histories of massive void galaxies as revealed by integral field spectroscopy

We present the first detailed integral field spectroscopy study of nine central void galaxies with M*>10¹⁰Mʘ using the Wide Field Spectrograph to determine how a range of assembly histories manifest themselves in the current day Universe.While the majority of these galaxies are evolving secularly, we find a range of morphologies, merger histories and stellar population distributions, though similarly low Hα-derived star formation rates (10¹⁰Mʘ have similarly low star formation rates

Tidal interactions at the edge of the Local Group: New evidence for tidal features in the Antlia Dwarf Galaxy

Using deep B band imaging down to mu_{B} = 26 mag arcsec^{-2}, we present evidence for tidal tails in the Antlia Dwarf galaxy, one of the most distant members of the Local Group. This elongation is in the direction of Antlia's nearest neighbor, the Magellanic-type NGC 3109. The tail is offset by less than 10 degrees from a vector linking the centers of the two galaxies, indicative of interactions between the pair. Combined with the warped disc previously identified in NGC 3109, Antlia and NGC 3109 must be at a small separation for tidal features to be present in Antlia. We calculate that Antlia cannot be completely disrupted by NGC 3109 in a single interaction unless its orbit pericenter is less than 6 kpc, however multiple interactions could significantly alter its morphology. Therefore despite being located right at the edge of the Local Group, environmental effects are playing an important role in Antlia's evolution.Comment: 8 pages, 4 figures, accepted for publication in ApJ

Implications for the origin of dwarf early-type galaxies: a detailed look at the isolated rotating dwarf early-type galaxy CG 611, with ramifications for the Fundamental Plane's (S_K)^2 kinematic scaling and the spin-ellipticity diagram

Selected from a sample of nine, isolated, dwarf early-type galaxies (ETGs) having the same range of kinematic properties as dwarf ETGs in clusters, we use CG 611 (LEDA 2108986) to address the Nature versus Nurture debate regarding the formation of dwarf ETGs. The presence of faint disk structures and rotation within some cluster dwarf ETGs has often been heralded as evidence that they were once late-type spiral or dwarf irregular galaxies prior to experiencing a cluster-induced transformation into an ETG. However, CG 611 also contains significant stellar rotation (~20 km/s) over its inner half light radius, R_(e,maj)=0.71 kpc, and its stellar structure and kinematics resemble those of cluster ETGs. In addition to hosting a faint young nuclear spiral within a possible intermediate-scale stellar disk, CG 611 has accreted an intermediate-scale, counter-rotating gas disk. It is therefore apparent that dwarf ETGs can be built by accretion events, as opposed to disk-stripping scenarios. We go on to discuss how both dwarf and ordinary ETGs with intermediate-scale disks, whether under (de)construction or not, are not fully represented by the kinematic scaling S_0.5=sqrt{ 0.5(V_rot)^2 + sigma^2 }, and we also introduce a modified spin-ellipticity diagram, lambda(R)-epsilon(R), with the potential to track galaxies with such disks.Comment: 15 pages (includes 9 figures and an extensive 2+ page reference list

Dwarf galaxies in the Perseus Cluster: further evidence for a disc origin for dwarf ellipticals

We present the results of a Keck-ESI (Echellette Spectrograph and Imager) spectroscopic study of six dwarf elliptical (dE) galaxies in the Perseus Cluster core, and confirm two dwarfs as cluster members for the first time. All six dEs follow the size–magnitude relation for dE/dSph galaxies. Central velocity dispersions are measured for three Perseus dwarfs in our sample, and all lie on the σ–luminosity relation for early-type, pressure-supported systems. We furthermore examine SA 0426-002, a unique dE in our sample with a bar-like morphology surrounded by low surface brightness wings/lobes (μB = 27 mag arcsec¯²). Given its morphology, velocity dispersion (σ₀ = 33.9 ± 6.1 km s⁻¹), velocity relative to the brightest cluster galaxy NGC 1275 (2711 km s⁻¹), size (Rₑ = 2.1 ± 0.10 kpc), and Sersic index ( ´ n = 1.2 ± 0.02), we hypothesize the dwarf has morphologically transformed from a low-mass disc to dE via harassment. The low surface brightness lobes can be explained as a ring feature, with the bar formation triggered by tidal interactions via speed encounters with Perseus Cluster members. Alongside spiral structure found in dEs in Fornax and Virgo, SA 0426-002 provides crucial evidence that a fraction of bright dEs have a disc infall origin, and are not part of the primordial cluster population