Effects of Spin on High-Energy Radiation from Accreting Black Holes

Observations of jets in X-ray binaries show a correlation between radio power and black hole spin. This correlation, if confirmed, points towards the idea that relativistic jets may be powered by the rotational energy of black holes. In order to examine this further, we perform general-relativistic radiative transport calculations on magnetically arrested accretion flows, which are known to produce powerful jets via the Blandford-Znajek (BZ) mechanism. We find that the X-ray and gamma-ray emission strongly depend on spin and inclination angle. Surprisingly, the high-energy power does not show the same dependence on spin as the BZ jet power, but instead can be understood as a redshift effect. In particular, photons observed perpendicular to the spin axis suffer little net redshift until originating from close to the horizon. Such observers see deeper into the hot, dense, highly-magnetized inner disk region. This effect is largest for rapidly rotating black holes due to a combination of frame dragging and decreasing horizon radius. While the X-ray emission is dominated by the near horizon region, the near-infrared radiation originates at larger radii. Therefore, the ratio of X-ray to near-infrared power is an observational signature of black hole spin.Comment: 15 pages, 13 figures, added panel in Figure 4 showing viewing angle dependence and extended the discussion in Section 4, accepted for publication in Ap

Knowledge creation: the hidden driver of innovation in the digital age

The importance of knowledge creation and innovation for organizational success is well established. At the same time, emerging technologies are ‘generative’ platforms with the capacity to produce unprompted change. At its core, innovation is a process of creating and using new ideas and concepts. As such, innovation may be conceptualized as a special class of knowledge creation. Further, the knowledge creation process is a driver of innovation. The paper develops a model of organizational knowledge creation and innovation to pinpoint the moments in the knowledge creation process where innovation occurs. The utility of the framework is illustrated with data from case studies on knowledge creation in innovative virtual world projects, which in turn reveals a set of strategies for driving knowledge creation and innovation in firms. The research has important implications for IS research on emerging technologies and user-generated and crowd-sourced innovation

CCT Assessment Design Workshop

This guest lecture by Dr O\u27 Riordan explores assessment types and principles, assessment feedback and technology enhanced assessment

INNOVATION IN VIRTUAL WORLDS: SOCIAL STRUCTURE AND DIFFUSION

This research-in-progress paper investigates the impact of social structures in virtual worlds (VWs) on the diffusion of innovations within them. Research has illustrated that innovation diffusion takes place within virtual worlds. VWs facilitate the emergence of purposeful communities which support the (often real-world) activities of their members including the development and adoption of innovations. Thus, VWs alter the social structures in which their users are embedded and the manner in which they communicate, both of which are thought to influence the diffusion of technical innovations amongst individuals. Though technical innovation is at the heart of Information Systems (IS) research, empirical research investigating innovation in the networked age is in its infancy. Thus, this paper presents a framework of propositions in relation to the impact of social structures on the diffusion of innovations within VWs and proposes the use of social network analysis to investigate these propositions

INNOVATION CO-CREATION IN A VIRTUAL WORLD

The emergence of web-based technologies has radically influenced the ways in which individuals around the world communicate, represent themselves, share ideas, and otherwise interact with one another (Ward and Sonneborn, 2009; Rogers, 2003). In particular, these technologies allow people to communicate directly with one another and to share and shape their own experiences; as a result, customers and other organisational stakeholders are increasingly involved in the design of products and services (Ramaswamy and Gouillart, 2010, p. 102). During innovation co-creation specifically, customers take an active and creative role in the intentional and successful adoption and application of ideas, processes, products or procedures that are new to the adopting organization. This study carries out six case studies of innovation co-creation in the virtual world of Second Life. Virtual worlds allow users to engage in highly active and participatory forms of co-creation that are difficult if not impossible to replicate in other environments. The study explores collaborative processes used for innovation co-creation in virtual worlds. In particular, the study presents an analysis of behaviours used to facilitate innovation co-creation in virtual world projects and the factors that affect it. The study leverages this analysis to derive practical recommendations for virtual world users and virtual world designers that can be used to stimulate and support innovation co-creation in virtual worlds