The X-ray and radio emission from SN 2002ap: The importance of Compton scattering

The radio and X-ray observations of the Type Ic supernova SN 2002ap are modeled. We find that inverse Compton cooling by photospheric photons explains the observed steep radio spectrum, and also the X-ray flux observed by XMM. Thermal emission from the shock is insufficient to explain the X-ray flux. The radio emitting region expands with a velocity of, roughly, 70,000 km/s. From the ratio of X-ray to radio emission we find that the energy densities of magnetic fields and relativistic electrons are close to equipartion.Comment: 15 pages, 2 figures, ApJ accepte

No trace of a single-degenerate companion in late spectra of SNe 2011fe and 2014J

Left-over, ablated material from a possible non-degenerate companion can reveal itself after about one year in spectra of Type Ia SNe (SNe Ia). We have searched for such material in spectra of SN 2011fe (at 294 days after the explosion) and for SN 2014J (315 days past explosion). The observations are compared with numerical models simulating the expected line emission. The spectral lines sought for are H-alpha, [O I] 6300 and [Ca II] 7291,7324, and the expected width of these lines is about 1000 km/s. No signs of these lines can be traced in any of the two supernovae. When systematic uncertainties are included, the limits on hydrogen-rich ablated gas in SNe 2011fe and 2014J are 0.003 M_sun and 0.0085 M_sun, respectively, where the limit for SN 2014J is the second lowest ever, and the limit for SN 2011fe is a revision of a previous limit. Limits are also put on helium-rich ablated gas. These limits are used, in conjunction with other data, to argue that these supernovae can stem from double-degenerate systems, or from single-degenerate systems with a spun up/spun down super-Chandrasekhar white dwarf. For SN 2011fe, other types of hydrogen-rich donors can likely be ruled out, whereas for SN 2014J a main-sequence donor system with large intrinsic separation is still possible. Helium-rich donor systems cannot be ruled out for any of the two supernovae, but the expected short delay time for such progenitors makes this possibility less likely, especially for SN 2011fe. The broad [Ni II] 7378 emission in SN 2014J is redshifted by about +1300 km/s, as opposed to the known blueshift of roughly -1100 km/s for SN 2011fe. [Fe II] 7155 is also redshifted in SN 2014J. SN 2014J belongs to a minority of SNe Ia that both have a nebular redshift of [Fe II] 7155 and [Ni II] 7378, and a slow decline of the Si II 6355 absorption trough just after B-band maximum.Comment: 13 pages, submitted to A&

Giving Sisyphus a helping hand : pathways for sustainable RIA systems in developing countries

This is the final version of the report. Available from the World Bank via the link in this record.This paper is a product of the Macroeconomics, Trade and Investment Global Practice and the Governance Global Practice. It is part of a larger effort by the World Bank to provide open access to its research and make a contribution to development policy discussions around the world.Regulatory impact assessment is a tool used by governments to support evidence-based and coordinated policy making. This paper contributes to the debate on regulatory impact assessment in developing countries by addressing the lack of a systematic account of reforms, and the lack of a comprehensive explanatory account of reform outcomes. The study first maps developing countries’ regulatory impact assessment reforms between 2001 and 2016. In total, 60 reforms are identified. Reform design is analyzed by measuring adherence to six internationally recognized “good practices.” The study then assesses whether the reforms—two years or more after they were launched—led to functioning regulatory impact assessment systems. Of the 60 reforms, 20 led to functional systems within two years of the conclusion of the reform. Three reforms were too recent to be assessed. The study shows that adherence to good practices is a necessary but not sufficient condition for early success. Among the six good practices, two are shown to be particularly decisive for the success of regulatory impact assessment reforms, namely, formal integration of regulatory impact assessment in policy making and the presence of a regulatory oversight unit. The second part of the study analyzes regulatory impact assessment reforms that did not produce early success despite adhering to good practices. The study tests several hypothetical reasons for slow developments. It points to the importance of donor flexibility and patience and the need for building reform constituencies inside and outside government. The traditional orthodoxy of regulatory impact assessment reforms as an extension of red tape reduction is challenged. The paper finally presents several possible policy implications of the findings.This project has been carried out under the World Bank's Good Regulatory Practice (GRP) program funded by USAID and DFID