Abstract
We investigate the prompt emission and the afterglow properties of short-duration gamma-ray burst (sGRB) 130603B and another eight sGRB events during 2012–2015, observed by several ...multiwavelength facilities including the Gran Canarias Telescope 10.4 m telescope. Prompt emission high energy data of the events were obtained by INTEGRAL-SPI-ACS, Swift-BAT, and Fermi-GBM satellites. The prompt emission data by INTEGRAL in the energy range of 0.1–10 MeV for sGRB 130603B, sGRB 140606A, sGRB 140930B, sGRB 141212A, and sGRB 151228A do not show any signature of the extended emission or precursor activity and their spectral and temporal properties are similar to those seen in case of other short bursts. For sGRB 130603B, our new afterglow photometric data constrain the pre-jet-break temporal decay due to denser temporal coverage. For sGRB 130603B, the afterglow light curve, containing both our new and previously published photometric data is broadly consistent with the ISM afterglow model. Modeling of the host galaxies of sGRB 130603B and sGRB 141212A using the LePHARE software supports a scenario in which the environment of the burst is undergoing moderate star formation activity. From the inclusion of our late-time data for eight other sGRBs we are able to: place tight constraints on the non-detection of the afterglow, host galaxy, or any underlying ‘kilonova’ emission. Our late-time afterglow observations of the sGRB 170817A/GW170817 are also discussed and compared with the sub-set of sGRBs.
ABSTRACT
We present MUSE spectroscopy, Megacam imaging, and Chandra X-ray emission for SPT-CL J0307-6225, a $z = 0.58$ major merging galaxy cluster with a large BCG-SZ centroid separation and a ...highly disturbed X-ray morphology. The galaxy density distribution shows two main overdensities with separations of 0.144 and 0.017 arcmin to their respective BCGs. We characterize the central regions of the two colliding structures, namely 0307-6225N and 0307-6225S, finding velocity derived masses of M200, N = 2.44 ± 1.41 × 1014M⊙ and M200, S = 3.16 ± 1.88 × 1014M⊙, with a line-of-sight velocity difference of |Δv| = 342 km s−1. The total dynamically derived mass is consistent with the SZ derived mass of 7.63 h$_{70}^{-1}$ ± 1.36 × 1014M⊙. We model the merger using the Monte Carlo Merger Analysis Code, estimating a merging angle of 36$^{+14}_{-12}$ ° with respect to the plane of the sky. Comparing with simulations of a merging system with a mass ratio of 1:3, we find that the best scenario is that of an ongoing merger that began 0.96$^{+0.31}_{-0.18}$ Gyr ago. We also characterize the galaxy population using Hδ and O ii λ3727 Å lines. We find that most of the emission-line galaxies belong to 0307-6225S, close to the X-ray peak position with a third of them corresponding to red-cluster sequence galaxies, and the rest to blue galaxies with velocities consistent with recent periods of accretion. Moreover, we suggest that 0307-6225S suffered a previous merger, evidenced through the two equally bright BCGs at the centre with a velocity difference of ∼674 km s−1.
This work presents an experimentally validated theoretical model for Mg alloy dissolution that accounts for transport phenomena. The galvanic interaction between AZ31 Mg alloy and low carbon steels ...in a solid electrolyte was simulated. The use of a solid agar-based electrolyte allowed to neglect the strong convective effects that are normally present during Mg alloy dissolution caused by copious hydrogen evolution. Furthermore, it allowed for a constant electrolyte thickness to be fixed. The gelled-electrolyte contained a pH indicator to permit a reliable visual tracking of the transient propagation of H+ and OH− ions during the electrochemical reaction.
The Aki-Utsu maximum likelihood method is widely used for estimation of the Gutenberg-Richter
b
-value, but not all authors are conscious of the method’s limitations and implicit requirements. The ...Aki/Utsu method requires a representative estimate of the population mean magnitude; a requirement seldom satisfied in
b
-value studies, particularly in those that use data from small geographic and/or time windows, such as
b
-mapping and
b
-vs-time studies. Monte Carlo simulation methods are used to determine how large a sample is necessary to achieve representativity, particularly for rounded magnitudes. The size of a representative sample weakly depends on the actual
b
-value. It is shown that, for commonly used precisions, small samples give meaningless estimations of
b
. Our results give estimates on the probabilities of getting correct estimates of
b
for a given desired precision for samples of different sizes. We submit that all published studies reporting
b
-value estimations should include information about the size of the samples used.
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