384 research outputs found
Strategies for prompt searches for GRB afterglows: the discovery of the GRB 001011 optical/near-infrared counterpart using colour-colour selection
We report the discovery of the optical and near-infrared counterparts to GRB
001011. The GRB 001011 error box determined by Beppo-SAX was simultaneously
imaged in the near-infrared by the 3.58-m New Technology Telescope and in the
optical by the 1.54-m Danish Telescope ~8 hr after the gamma-ray event. Here we
implement the colour-colour discrimination technique proposed by Rhoads (2001)
and extend it using near-IR data as well. We present the results provided by an
automatic colour-colour discrimination pipe-line developed to discern the
different populations of objects present in the GRB 001011 error box. Our
software revealed three candidates based on single-epoch images. Second-epoch
observations carried out ~3.2 days after the burst revealed that the most
likely candidate had faded, thus identifying it with the counterpart to the
GRB. In deep R-band images obtained 7 months after the burst a faint
(R=25.38+/-0.25) elongated object, presumably the host galaxy of GRB 001011,
was detected at the position of the afterglow. The GRB 001011 afterglow is the
first discovered with the assistance of colour-colour diagram techniques. We
discuss the advantages of using this method and its application to error boxes
determined by future missions.Comment: Accepted for publication in Astronomy and Astrophysics, 13 pages, 16
figure
Deep Ly-alpha imaging of two z=2.04 GRB host galaxy fields
We report on the results of deep narrow-band Ly-alpha, U and I imaging of the
fields of two GRBs at z=2.04 (GRB 000301C and GRB 000926). We find that the
host galaxy of GRB 000926 is an extended, strong Ly-alpha emitter with a
rest-frame equivalent width of 71+20-15 AA. The galaxy consists of two main
components and several fainter knots. GRB 000926 occurred in the western
component, whereas most of the Ly-alpha luminosity (about 65%) originates in
the eastern component. Using archival HST images of the host galaxy we measure
the spectral slopes (f_lambda prop. to lambda^beta) of the two components to
beta = -2.4+-0.3 (east) and -1.4+-0.2 (west). This implies that both components
contain at most small amounts of dust, consistent with the observed strong
Ly-alpha emission. The western component has a slightly redder V-I colour than
the eastern component, suggesting the presence of at least some dust. We do not
detect the host galaxy of GRB 000301C in neither Ly-alpha emission nor in U and
I-band images. We infer a limit of U(AB)>27.7 (2-sigma limit per arcsec^2). The
upper limits on the Ly-alpha flux implies a Ly-alpha equivalent width upper
limit of 150AA. We find 11 and 8 other galaxies with excess emission in the
narrow filter in the fields of GRB 000301C and GRB 000926 respectively. Based
on these detections we conclude that GRB 000926 occurred in one of the
strongest centres of star formation within several Mpc, whereas GRB 000301C
occurred in an intrinsically very faint galaxy far from being the strongest
centre of star formation in its galactic environment. Under the hypothesis that
GRBs trace star formation, the wide range of GRB host galaxy luminosities
implies a very steep faint end slope of the high redshift galaxy luminosity
function.Comment: 13 pages, 7 figures. Accepted for publication in A&
Strategies to prevent dopamine oxidation and related cytotoxicity using various antioxidants and nitrogenation
Measurements of fiducial and differential cross sections for Higgs boson production in the diphoton decay channel at s√=8 TeV with ATLAS
Measurements of fiducial and differential cross sections are presented for Higgs boson production in proton-proton collisions at a centre-of-mass energy of s√=8 TeV. The analysis is performed in the H → γγ decay channel using 20.3 fb−1 of data recorded by the ATLAS experiment at the CERN Large Hadron Collider. The signal is extracted using a fit to the diphoton invariant mass spectrum assuming that the width of the resonance is much smaller than the experimental resolution. The signal yields are corrected for the effects of detector inefficiency and resolution. The pp → H → γγ fiducial cross section is measured to be 43.2 ±9.4(stat.) − 2.9 + 3.2 (syst.) ±1.2(lumi)fb for a Higgs boson of mass 125.4GeV decaying to two isolated photons that have transverse momentum greater than 35% and 25% of the diphoton invariant mass and each with absolute pseudorapidity less than 2.37. Four additional fiducial cross sections and two cross-section limits are presented in phase space regions that test the theoretical modelling of different Higgs boson production mechanisms, or are sensitive to physics beyond the Standard Model. Differential cross sections are also presented, as a function of variables related to the diphoton kinematics and the jet activity produced in the Higgs boson events. The observed spectra are statistically limited but broadly in line with the theoretical expectations
Longitudinal associations between television in the bedroom and body fatness in a UK cohort study.
OBJECTIVE: To assess longitudinal associations between screen-based media use (television (TV) and computer hours, having a TV in the bedroom) and body fatness among UK children. METHODS: Participants were 12 556 children from the UK Millennium Cohort Study who were followed from age 7 to age 11 years. Associations were assessed between screen-based media use and the following outcomes: body mass index (BMI), fat mass index (FMI), and overweight. RESULTS: In fully adjusted models, having a bedroom TV at age 7 years was associated with significantly higher BMI and FMI (excess BMI for boys=0.29, 95% confidence interval (CI) 0.06-0.52; excess BMI for girls=0.57, 95% CI 0.31-0.84; excess FMI for boys=0.20, 95% CI 0.04-0.37; excess FMI for girls=0.39, 95% CI 0.21-0.57) and increased risk of being overweight (relative risk (RR) for boys=1.21, 95% CI 1.07-1.36; RR for girls=1.31, 95% CI 1.15-1.48) at age 11 years, compared with having no bedroom TV. Hours spent watching TV or digital versatile disks were associated with increased risk of overweight among girls only. Computer use at age 7 years was not related to later body fatness for either gender. CONCLUSION: Having a TV in the child's bedroom was an independent risk factor for overweight and increased body fatness in this nationally representative sample of UK children. Childhood obesity prevention strategies should consider TVs in children's bedrooms as a risk factor for obesity.International Journal of Obesity advance online publication, 27 June 2017; doi:10.1038/ijo.2017.129
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