English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Following the recent theoretical interpretation of GRB 090618 and GRB 101023,we here interpret GRB 970828 in terms of a double episode emission: the firstepisode, observed in the first 40 s of the emission, is interpreted as theproto-black-hole emission; the second episode, observed after t$_0$+50 s, as acanonical gamma ray burst. The transition between the two episodes marks theblack hole formation. The characteristics of the real GRB, in the secondepisode, are an energy of $E_{tot}^{e^+e^-} = 1.60 \times 10^{53}$ erg, abaryon load of $B = 7 \times 10^{-3}$ and a bulk Lorentz factor at transparencyof $\Gamma = 142.5$. The clear analogy with GRB 090618 would require also inGRB 970828 the presence of a possible supernova. We also infer that the GRBexploded in an environment with a large average particle density $<n> \,\approx 10^3$ part/cm$^3$ and dense clouds characterized by typical dimensionsof $(4 - 8) \times 10^{14}$ cm and $\delta n/n \propto 10$. Such an environmentis in line with the observed large column density absorption, which might havedarkened both the supernova emission and the GRB optical afterglow.

On the thermal and double episode emissions in GRB 970828