Deep images of cluster radio halos

New radio data are presented for the clusters A401, A545, A754, A1914, A2219 and A2390, where the presence of diffuse radio emission was suggested from the images of the NRAO VLA Sky Survey. Sensitive images of these clusters, obtained with the Very Large Array (VLA)at 20 cm confirm the existence of the diffuse sources and allow us to derive their fluxes and intrinsic parameters.The correlation between the halo radio power and cluster X-ray luminosity is derived for a large sample of halo clusters, and is briefly discussed.Comment: 9 pages, 13 figures, Astron. Astrophys. in pres

Internal dynamics of the galaxy cluster Abell 545

Diffuse radio emission in galaxy clusters, and their connection with cluster mergers, are still debated. We seek to explore the internal dynamics of the radio halo cluster Abell 545. This cluster is also peculiar for hosting in its center a very bright, red, diffuse intracluster light due to an old, stellar population, so bright to be named as "star pile". Our analysis is based on redshift data for 110 galaxies. We identify 95 cluster members and analyze the cluster internal dynamics by combining galaxy velocities and positions. We also use both photometric and X-ray data. We estimate the cluster redshift, z=0.1580, a velocity dispersion of 1200 km/s, and ICM temperature kT_X~8 keV. Our optical and X-ray analyses detect substructures. Optical data reveal three main galaxy clumps (center, NNW, and NE), and possibly a fourth clump at South. There is not a dominant galaxy and the four brightest galaxies avoid the cluster core (>~0.4h distant from the cluster center) and are >~1500 km/s far from the mean cluster velocity. The analysis of the X-ray surface brightness distribution provides us evidence of a disturbed dynamical phase. Located in the star pile region there is the brightest galaxies of the cluster core (CBCG) and a very compact elliptical galaxy. We show that the star pile has a similar redshift to that of the CBCG. Both the star pile and the CBCG are at rest in the cluster rest frame. The emerging picture of Abell 545 is that of a massive, M(R<1.6 h_70^-1 Mpc)=1.1-1.8x10^15 h_70^-1 Msun, very complex cluster with merging occurring along two directions. A545 gives another proof in the favor of the connection between cluster merger and extended, diffuse radio emission. The star pile, likely due to the process of a brightest galaxy forming in the cluster core. A545 represents a textbook cluster where to study the simultaneous formation of a galaxy system and its brightest galaxy.Comment: 16 pages, 11 figures and 2 tables. Accepted in A&

Cosmic rays and Radio Halos in galaxy clusters : new constraints from radio observations

Clusters of galaxies are sites of acceleration of charged particles and sources of non-thermal radiation. We report on new constraints on the population of cosmic rays in the Intra Cluster Medium (ICM) obtained via radio observations of a fairly large sample of massive, X-ray luminous, galaxy clusters in the redshift interval 0.2--0.4. The bulk of the observed galaxy clusters does not show any hint of Mpc scale synchrotron radio emission at the cluster center (Radio Halo). We obtained solid upper limits to the diffuse radio emission and discuss their implications for the models for the origin of Radio Halos. Our measurements allow us to derive also a limit to the content of cosmic ray protons in the ICM. Assuming spectral indices of these protons delta =2.1-2.4 and microG level magnetic fields, as from Rotation Measures, these limits are one order of magnitude deeper than present EGRET upper limits, while they are less stringent for steeper spectra and lower magnetic fields.Comment: 14 pages, 5 figures, ApJ Letter, accepte

Qualitative accounts of urban commuter cycling

Purpose ‐ The purpose of this paper is to explore the live experiences of urban commuter cycling (UCC). Design/methodology/approach ‐ In semi-structured interviews, participants described day-to-day experiences of UCC in a single English city. Verbatim transcripts were coded using the themes of time, space, body and human relations, and interpreted through the principles of hermeneutic phenomenology. Findings ‐ The nine participants (seven males, two females) were aged 27 to 54. Each regularly commuted by bicycle at least three times per week for "18 months" to "27 years". Strong influences on commuter cycling included the weather, daily tasks, cycling infrastructure, driver behaviour and the value of cycling for physical and mental well being. The contest for space was central to the UCC experience, with UCCs sensing they lacked respect despite feeling that they were "embodying citizenship" by enacting public policy. Due to their regular negative experiences, many UCCs were now willing to quit cycling and commute by car. Research limitations/implications ‐ Findings are limited to regular commuter cyclists and do little to describe the passage into regular cycling. Practical applications ‐ This paper highlights that cycle promoters and health educators may profit from focusing on road user interactions during the rush hour. Originality/value ‐ This paper addresses the untold day-to-day experiences of UCCs

A double radio halo in the close pair of galaxy clusters Abell 399 and Abell 401

Radio halos are faint radio sources usually located at the center of merging clusters of galaxies. These diffuse radio sources are rare, having so far been found only in about 30 clusters of galaxies, suggesting that particular conditions are needed to form and maintain them. It is interesting to investigate the presence of radio halos in close pairs of interacting clusters in order to possibly clarify their origin in relation to the evolutionary state of the merger. In this work, we study the case of the close pair of galaxy clusters A399 and A401. A401 is already known to contain a faint radio halo, while a hint of diffuse emission in A399 has been suggested based on the NVSS. To confirm this possibility, we analyzed deeper Very Large Array observations at 1.4 GHz of this cluster. We find that the central region of A399 is permeated by a diffuse low-surface brightness radio emission that we classify as a radio halo with a linear size of about 570 kpc and a central brightness of 0.3 micro-Jy/arcsec^2. Indeed, given their comparatively small projected distance of about 3 Mpc, the pair of galaxy clusters A401 and A399 can be considered as the first example of double radio halo system. The discovery of this double halo is extraordinary given the rarity of these radio sources in general and given that current X-ray data seem to suggest that the two clusters are still in a pre-merger state. Therefore, the origin of the double radio halo is likely to be attributed to the individual merging histories of each cluster separately, rather than to the result of a close encounter between the two systems.Comment: 6 pages, 4 figures, accepted for publication in A&

Excavating widening participation policy in Australian higher education: subject positions, representational effects, emotion

This article uses Foucauldian discourse analysis to identify two subject positions within Australia\u27s Widening Participation higher education policy. Purpose The massification of higher education is a definitive feature of the late twentieth century. Widening Participation (WP) policy is a recent manifestation of this phenomenon in Britain and Australia. This article uses Foucauldian discourse analysis to identify two subject positions within Australian WP higher education policy, that of the cap(able) individual and the proper aspirant. The article also traces the feeling-rules associated with these subject positions to ask critical questions about neo-liberal social justice. Design/methodology/approach A Foucauldian discourse analysis was conducted on a range of policy documents relating the higher education during the period 2008-2013. Using Bacchi’s (2012) ‘what is the problem represented to be?’ (WPR) approach, two subject positions and their attendant feeling-rules are identified.&nbsp;&nbsp;&nbsp; Findings The two subject positions, the cap(able) individual and the proper aspirant, represent a quintessential neo-liberal subject who possesses ‘natural’ ability, hope for social mobility and is highly individualised and entrepreneurial in disposition. As a reinvention of social justice approaches to higher education, WP has wide emotional and common sense appeal derived from its links into older discourses on social justice, meritocracy and the redemptive promise of education and childhood hope.&nbsp; A new neo-liberal appropriation of social justice, WP neglects critical historical, social and contextual factors related to educational inequity

A quiet politics of being together: Miriam and Rose

This paper draws on fieldwork with a befriending scheme that pairs refugees, asylum seekers and local residents in the north east of England. It explores the ways in which a ‘quiet politics’ of encounter, embedded in intimate relationships, is caught up in and productive of complex inter-scale geographies, highlighting the ebbs and flows across security and insecurity. Critically, it foregrounds the relationality of emotions in enabling and maintaining intimate-geopolitics

Troubling coalitions. Some remarks on the (hardly audible) voice of pro-equality men’s groups in gender equality advocacy

This paper sets off to outline some reflections on the subject position occupied by pro-equality men’s groups within overarching discourses of gender equality. Discussion makes reference to the cases of Men Engage Europe and Maschile Plurale, two loosely organized networks of men that support gender equality in different ways at the EU supranational-level and the Italian national-level respectively. Fragments of the voices of these organizations were gathered during two semi-structured interview conducted in the context of my doctoral fieldwork. This paper argues that men supporting gender equality attempt to participate in feminism from the difficult position of ‘unspoken’ subjects. More specifically, I argue that the tension between narrative of inclusion and narratives of ‘sisterhood’ within feminism produce overarching discourses of gender equality in which men’s subject position is unspoken. Based on these premises, I attempt to offer some reflections on what is gained and what is perhaps lost in the process.Praca ta ma na celu zarysowanie pozycji zajmowanej przez grupy mężczyzn z prorównościowych organizacji podczas dyskusji odwołujących się do tematu równości płci. Dyskusja odnosi się do przypadków Men Engage Europe i Maschile Plurale, dwóch luźno zorganizowanych grup mężczyzn, które wspierają równouprawnienie płci na różne sposoby, na poziomie ponadna­rodowym Unii Europejskiej, a także odwołując się do realiów panujących we włoskich miastach. Część głosów obu organizacji została zebrana podczas dwóch częściowo ustrukturyzowanych wywiadów przeprowadzonych w ramach mojej pracy doktorskiej. Praca argumentuje, że mężczyźni popierający równouprawnienie płci próbują uczestniczyć w feminizmie z trudnej pozycji „cichych” podmiotów. Mówiąc dokładniej, twierdzę, że podejście „siostrzanego ruchu” w feminizmie prowadzi do nadrzędnych dyskusji na temat równości płci, w których pozycja mężczyzny jest niewypowiedziana. Opierając się na tych przesłankach, staram się przedstawić pewne refleksje na temat tego, co zostało osiągnięte i co być może zagubiło się w tym procesie.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 67537

Valve actuator Patent

Actuator using compressed gas as driving force to control valve handling large liquid flow