1,122 research outputs found
Multilingual gendered identities: female undergraduate students in London talk about heritage languages
In this paper I explore how a group of female university students, mostly British Asian and in their late teens and early twenties, perform femininities in talk about heritage languages. I argue that analysis of this talk reveals ways in which the participants enact ‘culturally intelligible’ gendered subject positions. This frequently involves negotiating the norms of ‘heteronormativity’, constituting femininity in terms of marriage, motherhood and maintenance of heritage culture and language, and ‘girl power’, constituting femininity in terms of youth, sassiness, glamour and individualism. For these young women, I ask whether higher education can become a site in which they have the opportunities to explore these identifications and examine other ways of imagining the self and what their stories suggest about ‘doing being’ a young British Asian woman in London
The theory of spectral evolution of the GRB prompt emission
We develop the theory of jitter radiation from GRB shocks containing
small-scale magnetic fields and propagating at an angle with respect to the
line of sight. We demonstrate that the spectra vary considerably: the
low-energy photon index, , ranges from 0 to -1 as the apparent viewing
angle goes from 0 to . Thus, we interpret the hard-to-soft evolution and
the correlation of with the photon flux observed in GRBs as a combined
effect of temporal variation of the viewing angle and relativistic aberration
of an individual thin, instantaneously illuminated shell. The model predicts
that about a quarter of time-resolved spectra should have hard spectra,
violating the synchrotron line of death. The model also naturally
explains why the peak of the distribution of is at .
The presence of a low-energy break in the jitter spectrum at oblique angles
also explains the appearance of a soft X-ray component in some GRBs and a
relatively small number of them. We emphasize that our theory is based solely
on the first principles and contains no {\it ad hoc} (phenomenological)
assumptions.Comment: 5 pages, 3 figures, accepted to Ap
Angular Dependence of Jitter Radiation Spectra from Small-Scale Magnetic Turbulence
Jitter radiation is produced by relativistic electrons moving in turbulent
small-scale magnetic fields such as those produced by streaming Weibel-type
instabilities at collisionless shocks in weakly magnetized media. Here we
present a comprehensive study of the dependence of the jitter radiation spectra
on the properties of, in general, anisotropic magnetic turbulence. We have
obtained that the radiation spectra do reflect, to some extent, properties of
the magnetic field spatial distribution, yet the radiation field is anisotropic
and sensitive to the viewing direction with respect to the field anisotropy
direction. We explore the parameter space of the magnetic field distribution
and its effect on the radiation spectrum. Some important results include: the
presence of the harder-than-synchrotron segment below the peak frequency at
some viewing angles, the presence of the high-frequency power-law tail even for
a monoenergetic distribution of electrons, the dependence of the peak frequency
on the field correlation length rather than the field strength, the strong
correlation of the spectral parameters with the viewing angle. In general, we
have found that even relatively minor changes in the magnetic field properties
can produce very significant effects upon the jitter radiation spectra. We
consider these results to be important for accurate interpretation of prompt
gamma-ray burst spectra and possibly other sources.Comment: 75 pages, 29 figures, submitted to Ap
Measurements of Gamma-Ray Bursts (GRBs) with Glast
One of the scientific goals of the main instrument of GLAST is the study of
Gamma-Ray Bursts (GRBs) in the energy range from ~20 MeV to ~300 GeV. In order
to extend the energy measurement towards lower energies a secondary instrument,
the GLAST Burst Monitor (GBM), will measure GRBs from ~10 keV to ~25 MeV and
will therefore allow the investigation of the relation between the keV and the
MeV-GeV emission from GRBs over six energy decades. These unprecedented
measurements will permit the exploration of the unknown aspects of the
high-energy burst emission and the investigation of their connection with the
well-studied low-energy emission. They will also provide ne insights into the
physics of GRBs in general. In addition the excellent localization of GRBs by
the LAT will stimulate follow-up observations at other wavelengths which may
yield clues about the nature of the burst sources.Comment: 6 pages, 2 figures, to be published in Baltic Astronomy - Proceedings
of the minisymposium "Physics of Gamma-Ray Bursts", JENAM Conference, August
29-30, 2003, Budapes
- …