Social identity and health at mass gatherings

The Prayag Magh Mela research was funded by the ESRC (UK) research grant ‘Collective participation and social identification: A study of the individual, interpersonal and collective dimensions of attendance at the Magh Mela’ (RES-062-23-1449).Identifying with a group can bring benefits to physical and psychological health. These benefits can be found with both small-scale and large-scale social groups. However, groups can also be associated with health risks: a distinct branch of medicine (‘Mass Gathering Medicine’) has evolved to address the health risks posed by participating in events characterized by large crowds. We argue that emphasizing either the positive or the negative health consequences of group life is one-sided: both positive and negative effects on health can occur (simultaneously). Moreover, both such effects can have their roots in the same social psychological transformations associated with a group-based social identification. Reviewing evidence from across a range of mass gatherings, we offer a conceptual analysis of such mixed effects. Our account shows i., how social identity analyses can enrich mass gatherings medicine, and ii., how social identity analyses of health can be enriched by examining mass gatherings.PostprintPeer reviewe

The Origin and Evolution of the Galaxy Mass-Metallicity Relation

We use high-resolution cosmological zoom-in simulations from the Feedback in Realistic Environment (FIRE) project to study the galaxy mass-metallicity relations (MZR) from z=0-6. These simulations include explicit models of the multi-phase ISM, star formation, and stellar feedback. The simulations cover halo masses Mhalo=10^9-10^13 Msun and stellar mass Mstar=10^4-10^11 Msun at z=0 and have been shown to produce many observed galaxy properties from z=0-6. For the first time, our simulations agree reasonably well with the observed mass-metallicity relations at z=0-3 for a broad range of galaxy masses. We predict the evolution of the MZR from z=0-6 as log(Zgas/Zsun)=12+log(O/H)-9.0=0.35[log(Mstar/Msun)-10]+0.93 exp(-0.43 z)-1.05 and log(Zstar/Zsun)=[Fe/H]-0.2=0.40[log(Mstar/Msun)-10]+0.67 exp(-0.50 z)-1.04, for gas-phase and stellar metallicity, respectively. Our simulations suggest that the evolution of MZR is associated with the evolution of stellar/gas mass fractions at different redshifts, indicating the existence of a universal metallicity relation between stellar mass, gas mass, and metallicities. In our simulations, galaxies above Mstar=10^6 Msun are able to retain a large fraction of their metals inside the halo, because metal-rich winds fail to escape completely and are recycled into the galaxy. This resolves a long-standing discrepancy between "sub-grid" wind models (and semi-analytic models) and observations, where common sub-grid models cannot simultaneously reproduce the MZR and the stellar mass functions.Comment: 17 pages, 14 figures, re-submitted to MNRAS after revisions on referee comment

Submillimeter flux as a probe of molecular ISM mass in high-zz galaxies

Recent long wavelength observations on the thermal dust continuum suggest that the Rayleigh-Jeans (RJ) tail can be used as a time-efficient quantitative probe of the dust and ISM mass in high-$z$ galaxies. We use high-resolution cosmological simulations from the Feedback in Realistic Environment (FIRE) project to analyze the dust emission of $M_*>10^{10}\;M_{\odot}$ galaxies at $z=2-4$. Our simulations (MassiveFIRE) explicitly include various forms of stellar feedback, and they produce the stellar masses and star formation rates of high-$z$ galaxies in agreement with observations. Using radiative transfer modelling, we show that sub-millimeter (sub-mm) luminosity and molecular ISM mass are tightly correlated and that the overall normalization is in quantitative agreement with observations. Notably, sub-mm luminosity traces molecular ISM mass even during starburst episodes as dust mass and mass-weighted temperature evolve only moderately between $z=4$ and $z=2$, including during starbursts. Our finding supports the empirical approach of using broadband sub-mm flux as a proxy for molecular gas content in high-$z$ galaxies. We thus expect single-band sub-mm observations with ALMA to dramatically increase the sample size of high-$z$ galaxies with reliable ISM masses in the near future.Comment: 5 pages, 3 figures, accepted by MNRA

Relation Between Stellar Mass and Star Formation Activity in Galaxies

For a mass-selected sample of 66544 galaxies with photometric redshifts from the Cosmic Evolution Survey (COSMOS), we examine the evolution of star formation activity as a function of stellar mass in galaxies. We estimate the cosmic star formation rates (SFR) over the range 0.2 < z < 1.2, using the rest-frame 2800 A flux (corrected for extinction). We find the mean SFR to be a strong function of the galactic stellar mass at any given redshift, with massive systems (log (M/M(Sun)) > 10.5) contributing less (by a factor of ~ 5) to the total star formation rate density (SFRD). Combining data from the COSMOS and Gemini Deep Deep Survey (GDDS), we extend the SFRD-z relation as a function of stellar mass to z~2. For massive galaxies, we find a steep increase in the SFRD-z relation to z~2; for the less massive systems, the SFRD which also increases from z=0 to 1, levels off at z~1. This implies that the massive systems have had their major star formation activity at earlier epochs (z > 2) than the lower mass galaxies. We study changes in the SFRDs as a function of both redshift and stellar mass for galaxies of different spectral types. We find that the slope of the SFRD-z relation for different spectral type of galaxies is a strong function of their stellar mass. For low and intermediate mass systems, the main contribution to the cosmic SFRD comes from the star-forming galaxies while, for more massive systems, the evolved galaxies are the most dominant population.Comment: 34 pages; 8 figures; Accepted for publication in Ap

On the dust temperatures of high redshift galaxies

Dust temperature is an important property of the interstellar medium (ISM) of galaxies. It is required when converting (sub)millimeter broadband flux to total infrared luminosity (L_IR), and hence star formation rate, in high-z galaxies. However, different definitions of dust temperatures have been used in the literature, leading to different physical interpretations of how ISM conditions change with, e.g., redshift and star formation rate. In this paper, we analyse the dust temperatures of massive (M* > 10^10 Msun) z=2-6 galaxies with the help of high-resolution cosmological simulations from the Feedback in Realistic Environments (FIRE) project. At z~2, our simulations successfully predict dust temperatures in good agreement with observations. We find that dust temperatures based on the peak emission wavelength increase with redshift, in line with the higher star formation activity at higher redshift, and are strongly correlated with the specific star formation rate. In contrast, the mass-weighted dust temperature does not strongly evolve with redshift over z=2-6 at fixed IR luminosity but is tightly correlated with L_IR at fixed z. The mass-weighted temperature is important for accurately estimating the total dust mass. We also analyse an 'equivalent' dust temperature for converting (sub)millimeter flux density to total IR luminosity, and provide a fitting formula as a function of redshift and dust-to-metal ratio. We find that galaxies of higher equivalent (or higher peak) dust temperature ('warmer dust') do not necessarily have higher mass-weighted temperatures. A 'two-phase' picture for interstellar dust can explain the different scaling relations of the various dust temperatures.Comment: 26 pages, 15 figures, accepted for publication in MNRA

Psychology and culture:Back to the future?

Psychology has a poor record in addressing cultural phenomena. One response is to turn to ancient concepts from local traditions and to use these as alternative analytic categories to explain behavior. However, there are problems with such an approach. These concepts will be read from the vantage point of the present and interpreted differently so as to propose different diagnoses (and solutions) for contemporary social problems. As an alternative, rather than using ancient resources as analytic categories in the explanation of behavior, we could instead examine how they are used as categories of practice as people actively make sense of their social context and themselves. Attending to such contemporary ‘lay’ usage (and the contestation it entails) allows for a more dynamic conception of cultural processes than is typical in psychology. More generally, I believe that it is possible to use our psychological constructs so that we can see the distinctive particularities of the phenomena before us in new and interesting ways, and in ways that respect their cultural specificity. This claim is illustrated through reference to recent work using the concept of social identity to illuminate aspects of Hindu pilgrimage

Categorising the sub-mJy population: Star-forming galaxies from deep radio surveys

Models predict that starforming galaxies make up the majority of the source population detected in the very deepest radio surveys. Radio selected samples of starforming galaxies are therefore a potentially excellent method to chart e.g. the cosmic history of star-formation. However, a significant minority of the faintest radio sources are AGN powered ‘contaminants’, and must be removed from any solely star-formation powered sample. Here we describe a multi-pronged method for spearating star-forming and AGN powered sources in a deep 1.4 GHz radio survey. We utilise a wealth of multi-wavelength information, including radio spectral and morphological information and radio to mid-IR SED modelling, to select a clean sample of star-formation powered sources. We then derive the 1.4 GHz source counts separately for AGN and SFGs, calculate an independent measure of the evolving star-formation rate density to z∼2, and compare our results to the star-formation rate density determined at other wavelengths

Identity enactment as a social accomplishment:Shared identity and the provision of mutual support amongst pilgrims undertaking the Hajj

Experimental and survey research shows that a common group membership can result in increased levels of social support. Here we complement such research with qualitative data concerning the forms and function of such support. Specifically, we explore the mutual support reported by pilgrims undertaking the Hajj. This requires participants enact a series of identity-related beliefs and values (including specific rituals) in conditions that are practically and psychologically challenging. Using data obtained through semi-structured interviews (N = 33), we investigate how participants' shared identity facilitated their behavioural enactment of these identity-defining beliefs and values. We focus on how their shared understanding of their beliefs and values as Hajj pilgrims allowed various forms of support (psychological, material, informational, and behavioural) which helped participants translate their identity-related ideals into behaviour. Our analysis implies that a shared identity provides a frame of reference with which group members can recognize each other's identity-related concerns and what they need in order to enact their identity. In turn, it implies that in situations where there are practical and psychological constraints on behaviour, action in terms of one's social identity can be conceptualized as a joint accomplishment in which the mutual support of group members is key.</p

Organisational practices and social inclusion:Inclusionary place‐making in the library

Social psychology has long been concerned with social exclusion. Much of this interest has focused on people's negative intergroup attitudes and how these may be changed through individual-level interventions. In this paper we explore a different level of intervention – one that targets the routine organisational practices that communicate who is welcome and able to draw on the organisation's services. Specifically, we investigate how a public-facing organisation—a library service—engaged in a process of self-reflection on its routine social practices with the aim of making people experiencing various forms of exclusion (e.g., job seekers, benefit claimants, ethnic minorities) more welcome. Our data arise from interviews (N = 19) with staff concerning their attempts to transform the practices that constitute the library as a distinctive public place. Throughout, we explore how they reflected on their everyday organisational practices, how these may unintentionally exclude, and how they could be modified to facilitate social inclusion. Moreover, we pay particular attention to our participants' understanding of the challenges involved in changing organisational culture and creating a social space in which diversity is accepted