Measuring the spin of the primary black hole in OJ287

The compact binary system in OJ287 is modelled to contain a spinning primary black hole with an accretion disk and a non-spinning secondary black hole. Using Post Newtonian (PN) accurate equations that include 2.5PN accurate non-spinning contributions, the leading order general relativistic and classical spin-orbit terms, the orbit of the binary black hole in OJ287 is calculated and as expected it depends on the spin of the primary black hole. Using the orbital solution, the specific times when the orbit of the secondary crosses the accretion disk of the primary are evaluated such that the record of observed outbursts from 1913 up to 2007 is reproduced. The timings of the outbursts are quite sensitive to the spin value. In order to reproduce all the known outbursts, including a newly discovered one in 1957, the Kerr parameter of the primary has to be $0.28 \pm 0.08$. The quadrupole-moment contributions to the equations of motion allow us to constrain the `no-hair' parameter to be $1.0\:\pm\:0.3$ where 0.3 is the one sigma error. This supports the `black hole no-hair theorem' within the achievable precision. It should be possible to test the present estimate in 2015 when the next outburst is due. The timing of the 2015 outburst is a strong function of the spin: if the spin is 0.36 of the maximal value allowed in general relativity, the outburst begins in early November 2015, while the same event starts in the end of January 2016 if the spin is 0.2Comment: 12 pages, 6 figure

Testing black hole no-hair theorem with OJ287

We examine the ability to test the black hole no-hair theorem at the 10% level in this decade using the binary black hole in OJ287. In the test we constrain the value of the dimensionless parameter q that relates the scaled quadrupole moment and spin of the primary black hole: q2 = -q 2 . At the present we can say that q = 1 \pm 0.3 (one), in agreement with General Relativity and the no-hair theorems. We demonstrate that this result can be improved if more observational data is found in historical plate archives for the 1959 and 1971 outbursts. We also show that the predicted 2015 and 2019 outbursts will be crucial in improving the accuracy of the test. Space-based photometry is required in 2019 July due the proximity of OJ287 to the Sun at the time of the outburst. The best situation would be to carry out the photometry far from the Earth, from quite a different vantage point, in order to avoid the influence of the nearby Sun. We have considered in particular the STEREO space mission which would be ideal if it has a continuation in 2019 or LORRI on board the New Horizons mission to Pluto.Comment: 14 pages, 14 figure

Impact of employees´ professional backgrounds on organizational identity and project chemistry in the construction industry

This thesis is based on a case study performed at one of the largest engineering and consulting companies in Sweden, which operates within the energy-, industrial- and infrastructure sector. The segment of the company operating in the construction industry is expanding rapidly and recruits heavily through mergers with smaller existing consulting companies and through recruiting individuals from contractor companies. This results in people with backgrounds from different trades in the industry working side by side in what seems to be a highly heterogeneous organization. This study aims to examine what impact the varying professional backgrounds of the employees, working in the construction industry at the mentioned company, have on the organizational identity. The purpose is also to analyse what consequences these various backgrounds have on project chemistry. The aim is pursued using an identity theory lens to analyse the findings from the case study. The study revealed that there exist a strong social identity of “Being a contractor” among the people with backgrounds in contracting companies, i.e. who have experience from onsite construction work. The interviews showed that the individuals with onsite experience, now working as consultants, refused to adopt the epithet of “consultant”. They chose to spend all their working hours at the constructions sites with the project’s contractors and not at the office with their consultant colleagues. The findings indicate that people with experience from building sites identify themselves foremost with “Being a contractor” rather than with an organizational identity. This became extra clear in one interview where one of these individuals was interviewed at a construction site and was wearing both jacket and hard hat with the contractor’s logo. The only visible connection to the consultant’s own company was a discreet logo on a key string around the neck, partly concealed by the jacket. There was a dominant narrative attached to the identity of “Being a contractor” which often resulted in these members displaying resistance towards project participants who lack experience from onsite construction work. One interview was conducted with two individuals at the same time, one of the respondents had this experience and the other one lacked it. The interviewees stated that they were friends but throughout the interview they questioned each other's’ views and statements, which was a result of the mindset in their particular professional backgrounds. This interaction made it clear how a professional background entails a specific narrative and that these narratives seem to block not only other narratives but also a common organizational identity. The authors to this thesis argue that this resistance can have a negative impact on project chemistry and on overall project success

Measuring Black Hole Spin in OJ287

We model the binary black hole system OJ287 as a spinning primary and a non-spinning secondary. It is assumed that the primary has an accretion disk which is impacted by the secondary at specific times. These times are identified as major outbursts in the light curve of OJ287. This identification allows an exact solution of the orbit, with very tight error limits. Nine outbursts from both the historical photographic records as well as from recent photometric measurements have been used as fixed points of the solution: 1913, 1947, 1957, 1973, 1983, 1984, 1995, 2005 and 2007 outbursts. This allows the determination of eight parameters of the orbit. Most interesting of these are the primary mass of $1.84\cdot 10^{10} M_\odot$, the secondary mass $1.46\cdot 10^{8} M_\odot$, major axis precession rate $39^\circ.1$ per period, and the eccentricity of the orbit 0.70. The dimensionless spin parameter is $0.28\:\pm\:0.01$ (1 sigma). The last parameter will be more tightly constrained in 2015 when the next outburst is due. The outburst should begin on 15 December 2015 if the spin value is in the middle of this range, on 3 January 2016 if the spin is 0.25, and on 26 November 2015 if the spin is 0.31. We have also tested the possibility that the quadrupole term in the Post Newtonian equations of motion does not exactly follow Einstein's theory: a parameter $q$ is introduced as one of the 8 parameters. Its value is within 30% (1 sigma) of the Einstein's value $q = 1$. This supports the $no-hair theorem$ of black holes within the achievable precision. We have also measured the loss of orbital energy due to gravitational waves. The loss rate is found to agree with Einstein's value with the accuracy of 2% (1 sigma).Comment: 12 pages, 4 figures, IAU26

Optical polarization angle and VLBI jet direction in the binary black hole model of OJ287

We study the variation of the optical polarization angle in the blazar OJ287 and compare it with the precessing binary black hole model with a 'live' accretion disk. First, a model of the variation of the jet direction is calculated, and the main parameters of the model are fixed by the long term optical brightness evolution. Then this model is compared with the variation of the parsec scale radio jet position angle in the sky. Finally, the variation of the polarization angle is calculated using the same model, but using a magnetic field configuration which is at a constant angle relative to the optical jet. It is found that the model fits the data reasonably well if the field is almost parallel to the jet axis. This may imply a steady magnetic field geometry, such as a large-scale helical field.Comment: to appear in Monthly Notices of Royal Astronomical Societ

The Nature of Starburst Activity in M82

We present new evolutionary synthesis models of M82 based mainly on observations consisting of near-infrared integral field spectroscopy and mid-infrared spectroscopy. The models incorporate stellar evolution, spectral synthesis, and photoionization modeling, and are optimized for 1-45 micron observations of starburst galaxies. The data allow us to model the starburst regions on scales as small as 25 pc. We investigate the initial mass function (IMF) of the stars and constrain quantitatively the spatial and temporal evolution of starburst activity in M82. We find a typical decay timescale for individual burst sites of a few million years. The data are consistent with the formation of very massive stars (> 50-100 Msun) and require a flattening of the starburst IMF below a few solar masses assuming a Salpeter slope at higher masses. Our results are well matched by a scenario in which the global starburst activity in M82 occurred in two successive episodes each lasting a few million years, peaking about 10 and 5 Myr ago. The first episode took place throughout the central regions of M82 and was particularly intense at the nucleus while the second episode occurred predominantly in a circumnuclear ring and along the stellar bar. We interpret this sequence as resulting from the gravitational interaction M82 and its neighbour M81, and subsequent bar-driven evolution. The short burst duration on all spatial scales indicates strong negative feedback effects of starburst activity, both locally and globally. Simple energetics considerations suggest the collective mechanical energy released by massive stars was able to rapidly inhibit star formation after the onset of each episode.Comment: 48 pages, incl. 16 Postscript figures; accepted for publication in the Astrophysical Journa

Simulations of the grand design galaxy M51: a case study for analysing tidally induced spiral structure

We present hydrodynamical models of the grand design spiral M51 (NGC 5194), and its interaction with its companion NGC 5195. Despite the simplicity of our models, our simulations capture the present day spiral structure of M51 remarkably well, and even reproduce details such as a kink along one spiral arm, and spiral arm bifurcations. We investigate the offset between the stellar and gaseous spiral arms, and find at most times (including the present day) there is no offset between the stars and gas to within our error bars. We also compare our simulations with recent observational analysis of M51. We compute the pattern speed versus radius, and like the observations, find no single global pattern speed. We also show that the spiral arms cannot be fitted well by logarithmic spirals. We interpret these findings as evidence that M51 does not exhibit a quasi-steady density wave, as would be predicted by density wave theory. The internal structure of M51 derives from the complicated and dynamical interaction with its companion, resulting in spiral arms showing considerable structure in the form of short-lived kinks and bifurcations. Rather than trying to model such galaxies in terms of global spiral modes with fixed pattern speeds, it is more realistic to start from a picture in which the spiral arms, while not being simple material arms, are the result of tidally induced kinematic density `waves' or density patterns, which wind up slowly over time.Comment: 23 pages, 20 figures, accepted for publication in MNRA

A search for periodicity in the light curves of selected blazars

We present an analysis of multifrequency light curves of the sources 2223-052 (3C 446), 2230+114 (CTA 102), and 2251+158 (3C 454.3), which had shown evidence of quasi-periodic activity. The analysis made use of data from the University of Michican Radio Astronomy Observatory (USA) at 4.8, 8, and 14.5 GHz, as well as the Metsahovi Radio Astronomy Observatory (Finland) at 22 and 37 GHz. Application of two different methods (the discrete autocorrelation function and the method of Jurkevich) both revealed evidence for periodicity in the flux variations of these sources at essentially all frequencies. The periods derived for at least two of the sources -- 2223-052 and 2251+158-- are in good agreement with the time interval between the appearance of successive VLBI components. The derived periods for 2251+158 (P = 12.4 yr and 2223-052 (P = 5.8 yr) coincide with the periods found earlier by other authors based on optical light curves.Comment: 27 pages, 11 figures, accepted for publication in Astronomy Report

Hybrida Ängelholm – En studie om Agila policys i offentlig sektor

Syfte : Studiens syfte är att undersöka Agila policys problembeskrivning, genom fallet Agila Ängelholm. Studien syftar även till att undersöka hur problembeskrivning det Agilas kan förstås i förhållande till New public management Digital Era Governance respekt Teori : ive problembeskrivningar . och Studien använder i huvudsak Bacchis (2009) perspektiv på policyproblem med tillhörande analysverktyg. För att uppnå studiens syfte använd e s även New Public management och Digital Era Governance som teoretiska utgångspunkter. Metod : Resultat Studiens metod består av en dokumentanalys av policydokument och semistrukturerade intervjuer med tjänstemän. : Studien presenterar resultat och ti llhörande analys i två delar. Resultatanalys del 1 visar på att Agila Ängelholms problembeskrivning gör gällande att Ängelholms kommun tidigare sätt att arbeta inte längre är ändamålsenligt för att kunna ge medborgarna god service och inte utformat för en allt snabbare samhällsutveckling. I problembeskrivningen framgår det att kommunens syn på sitt uppdrag och medborgarna är i förändring. I resultatanalys del 2 används policyn Agila Ängelholms problembeskrivning för att förstå förhållandet till DEG och NPM. Studien kan här bl.a. visa på att det finns tydliga likheter mellan trendernas problembeskrivningar och att Agila Ängelholm kan beskrivas som en hybrid av DEG och NPM

Stretching the IR theoretical spectrum on Irish neutrality: a critical social constructivist framework

In a 2006 International Political Science Review article, entitled "Choosing to Go It Alone: Irish Neutrality in Theoretical and Comparative Perspective," Neal G. Jesse argues that Irish neutrality is best understood through a neoliberal rather than a neorealist international relations theory framework. This article posits an alternative "critical social constructivist" framework for understanding Irish neutrality. The first part of the article considers the differences between neoliberalism and social constructivism and argues why critical social constructivism's emphasis on beliefs, identity, and the agency of the public in foreign policy are key factors explaining Irish neutrality today. Using public opinion data, the second part of the article tests whether national identity, independence, ethnocentrism, attitudes to Northern Ireland, and efficacy are factors driving public support for Irish neutrality. The results show that public attitudes to Irish neutrality are structured along the dimensions of independence and identity, indicating empirical support for a critical social constructivist framework of understanding of Irish neutrality