Variable jet properties in GRB 110721A: time resolved observations of the jet photosphere

Iyyani, ShabnamStockholms universitet,Fysikum,Oskar Klein-centrum för kosmopartikelfysik (OKC),KTH Royal Institute of Technology, Sweden (author)

Variable jet properties in GRB 110721A : time resolved observations of the jet photosphere

AuthorCount:11;
QC 20130902
Fermi Gamma-ray Space Telescope observations of GRB 110721A have revealed two emission components from the relativistic jet: emission from the photosphere, peaking at similar to 100 keV, and a non-thermal component, which peaks at similar to 1000 keV. We use the photospheric component to calculate the properties of the relativistic outflow. We find a strong evolution in the flow properties: the Lorentz factor decreases with time during the bursts from G similar to 1000 to similar to 150 (assuming a redshift z = 2; the values are only weakly dependent on unknown efficiency parameters). Such a decrease is contrary to the expectations from the internal shocks and the isolated magnetar birth models. Moreover, the position of the flow nozzle measured from the central engine, r(0), increases by more than two orders of magnitude. Assuming a moderately magnetized outflow we estimate that r(0) varies from 10(6) to similar to 10(9) cm during the burst. We suggest that the maximal value reflects the size of the progenitor core. Finally, we show that these jet properties naturally explain the observed broken power-law decay of the temperature which has been reported as a characteristic for gamma-ray burst pulses.

Ryde, FelixKTH,Partikel- och astropartikelfysik(Swepub:kth)u1tlyg6w (author)
Axelsson, MagnusKTH,Stockholms universitet,Fysikum,Institutionen för astronomi,Oskar Klein-centrum för kosmopartikelfysik (OKC),KTH Royal Institute of Technology, Sweden,Fysik(Swepub:kth)u1pcmyc0 (author)
Burgess, J. M. (author)
Guiriec, S. (author)
Larsson, JosefinKTH,Partikel- och astropartikelfysik(Swepub:kth)u12o773l (author)
Lundman, ChristofferKTH,Partikel- och astropartikelfysik(Swepub:kth)u1q20wv4 (author)
Moretti, ElenaKTH,Partikel- och astropartikelfysik(Swepub:kth)u1t69eg4 (author)
McGlynn, S. (author)
Nymark, TanjaKTH,Fysik(Swepub:kth)u14p8rnp (author)
Rosquist, KjellStockholms universitet,Fysikum,Oskar Klein-centrum för kosmopartikelfysik (OKC),ICRANet, Italy(Swepub:su)kr (author)
Stockholms universitetFysikum (creator_code:org_t)

In:Monthly notices of the Royal Astronomical Society: Oxford University Press (OUP)433:4, s. 2739-27480035-87111365-2966

By the author/editor: Iyyani, Shabnam; Ryde, Felix; Axelsson, Magnus; Burgess, J. M.; Guiriec, S.; Larsson, Josefin; show more...; Lundman, Christo ...; Moretti, Elena; McGlynn, S.; Nymark, Tanja; Rosquist, Kjell; show less...

About the subject

NATURAL SCIENCES: NATURAL SCIENCES; and Physical Science ...; and Astronomy Astrop ...

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.