tudij izbruhov sevanja gama v dobi satelita Fermidunja/AD/presentations/AD...Uvod Detekcija Opazovanja Teorija in diskusijaZaklju cek Studij izbruhov sevanja gama v dobi satelita Fermi

Uvod Detekcija Opazovanja Teorija in diskusija Zakljucek

Studij izbruhov sevanja gama v dobi satelita Fermi

Drejc Kopac

Fakulteta za matematiko in fizikoUniverza v Ljubljani

23. november 2010


Pregled predstavitve1 Uvod

Satelit FermiIzstrelitevElementi misije

2 DetekcijaLATGBM

3 OpazovanjaStatistika opazovanjLastnosti svetlobnih krivuljSpektralne lastnostiEnergetske lastnosti in Lorentzov faktor

4 Teorija in diskusijaSvetlobne krivuljeTri spektralne komponenteVelik Lorentzov faktor

5 Zakljucek


Instrumenti

Large Area Telescope (LAT)

20 MeV – 300 GeV

> 2.5 sr FoV

Gamma-Ray Burst Monitor (GBM)

8 keV – 40 MeV

9 sr FoV


Instrumenti

,/ **2 2 '313

"4/')

**2 2 5-3'3+

$ 6-34'3


Izstrelitev

Cape Canaveral, Florida

11. junij 2008

Raketa Delta II

Krozna orbita

Visina: 565 km

Perioda: 96 min

Inklinacija: 25.6 deg

Zivljenjska doba:

zahteva = 5 letcilj = 10 let


Elementi misije

4

GLAST MISSION ELEMENTSGLAST MISSION ELEMENTS

GN

HEASARC

GSFC

-

-

DELTA

7920H

White Sands

TDRSS SNS & Ku

LAT Instrument

Science

Operations Center

(SLAC)

GBM Instrument

Operations Center

(MSFC)

GRB

Coordinates Network

(GSFC)

Telemetry 1 kbps

-

S

Alerts

Data, Command Loads

Schedules

Schedules

Mission Operations

Center (GSFC)

Fermi Science

Support Center

(FSSC)

µsec

Fermi Spacecraft

Large Area Telescope

& GBMGPS

Fermi MISSION ELEMENTS


Zgradba LAT detektorja in detekcija MeV fotonov

Glavni mehanizem absorbcije v snovi za γ nad 10 MeV: γ → e+e−

e+ e

γ

Calorimeter

Tracker

ACD [surrounds 4x4 array of TKR towers]

Precision Si-strip Tracker (TKR)

18 XY tracking planes. 228 m pitch.

High efficiency.

Good position resolution (ang. resolution at HE).

12 x 0.03 X0 front-end => reduce multiple scattering

4 x 0.18 X0 back-end => increase sensitivity >1GeV

CsI Calorimeter(CAL)

Array of 1536 CsI(Tl) crystals in 8 layers.

Hodoscopic => CR rejection, shower leakage correction.

8.5 X0 => Shower max contained <100 GeV

Anticoincidence Detector (ACD)

Segmented (89 plastic scintillator tiles).

=> minimize self veto

LAT meri fluks gama sevanja z energijami od 20 MeV do 300 GeV.

LAT: 4x4 mrea stolpov

3000 kg

1.8 m × 1.8 m × 1.0 m


LAT detekcija in lokalizacija

Detekcija

Povisan fluks (clustered tracks)

Posredno preko GBM detekcije

Boljsa locljivost pri visjih energijah

Manjsa napaka pri velikih inklinacijah

Lokalizacija na krovu

Par sekund po detekciji

Natancnost: 0.1 − 0.5

Lokalizacija na Zemlji

> 8 ur po zaznavi

opravi dezurni Burst Advocate

Hitra dolocitev lokacije omogocaopazovanja z drugimi instrumenti (Swift).

75

(.(/)012

34)

θ45(

(.(.512

3450("

θ40(

75

90.:/(:

&*;;;((/*#<*6(6*5.(


GBM detektorji

Delujejo na principu scintilatorjev (NaI, BGO)

Vsak detektor vidi svoj del neba in deluje kot posamezna enota.

Zaradi dobre casovne resolucije in energijskega razpona (8 keV – 40 MeV) odlicen za spektralno analizo.


GBM detekcija in lokalizacija

Lokalizacija izvora na krovu v par sekundah, vendar slaba (< 15)

Lokalizacija izvora na Zemlji je boljsa (< 5), vendar traja vec minut

Iscejo se boljsi nacini lokalizacije

Izboljsava GBM lokalizacije

Iz LAT podatkov po detekciji z GBM

Iz podatkov drugih instrumentov (BAT) – ne na krovu


GBM detekcija in lokalizacija

Lokalizacija izvora na krovu v par sekundah, vendar slaba (< 15)

Lokalizacija izvora na Zemlji je boljsa (< 5), vendar traja vec minut

Iscejo se boljsi nacini lokalizacije

Izboljsava GBM lokalizacije

Iz LAT podatkov po detekciji z GBM

Iz podatkov drugih instrumentov (BAT) – ne na krovu


Detektirani GRB-ji do 4. avgusta 2010

!"#"#

)((*(+,-

,". # "

V pripravi je prvi Fermijev LAT katalog GRB-jev:

Tipicni parametri: T90, Favg, Fpeak, tpeak, ipd.

HE parametri: delayed onset, spectral evolution, ipd.


Stevilo detekcij z GBM


LAT detekcije (do septembra 2009)


GRB 080916C - svetlobne krivulje pri razlicnih energijah

(.(/)01 &' 7%'&*;;;((/*B' '*)0..

1 in 2 kazeta GBM(NaI in BGO)

3 kaze LLE (“LAT low energy“)

4 in 5 kazeta LAT HE(high energy)

GeV emisija kasneje kot keV – MeV


Zakasnjena HE emisija

Kumulativne svetlobne krivulje:

- crna: > 50 MeV

- rdeca: > 100 MeV

- modra: > 200 MeV

- zelena: > 400 MeV

visja energija⇓

vecja zakasnitev


GRB 090902B - svetlobne krivulje in dolgoziva HE emisija

0 20 40 60 80

Co

un

ts/B

in

0

200

400

RA

TE

[H

z]

0

2000

4000

aa ba b ca b c da b c d ea b c d e fa b c d e f g

+ 2

+ NaI1

+ NaI0

GBM NaI

10 + NaI

9 + NaI

(8 keV-14.3 keV)

Time since trigger (s)

0 10 20 30

Co

un

ts/b

in

0

5000

0 20 40 60 80

Co

un

ts/B

in

0

1000

2000

3000

RA

TE

[H

z]

0

10000

20000

30000 +

2 + NaI

1 + NaI

0GBM NaI

10 + NaI

9 + NaI

(14.3 keV-260 keV)

Time since trigger (s)0 10 20 30

Co

un

ts/b

in

0

50000

100000

0 20 40 60 80

Co

un

ts/B

in

0

200

400

600

800

RA

TE

[H

z]

0

2000

4000

60001

+GBM BGO0

GBM BGO

(260 keV-5 MeV)

Time since trigger (s)

0 10 20 30

Co

un

ts/b

in

0

10000

20000

0 20 40 60 80

Co

un

ts/B

in

0

20

40

60

RA

TE

[H

z]

0

200

LAT

(All events)

0 20 40 60 80

Co

un

ts/B

in

0

2

4R

AT

E [

Hz]

0

10

20LAT

(> 100 MeV)

Time since trigger (s)0 10 20 30

Co

un

ts/b

in

0

20

40

0Time since T

0 20 40 60 80

En

erg

y [

Me

V]

310

410

LAT EVENTS

(> 1 GeV)

Abdo et al., 2009

0.1–100 GeV fluks:

10-1 100 101 102 103

T - T0 (s)

10-8

10-7

10-6

10-5

10-4

10-3

10-2

ph

oto

n f

lux (

cm

-2s

-1)

Dolgoziva HE emisija


GRB 090510 - svetlobne krivulje in dolgoziva HE emisija

Time since BAT trigger (s)

−110 1 10210

310 410

510

Flu

x d

en

sit

y (

Jy)

−1110

−1010

−910

−810

−710

−610

−510

−410

−310

−210

LAT

GBM

XRT

BAT

UVOT

de Pasquale et al., 2009

Ackermann et al., 2010

Casovne lastnosti

Kratek GRB glede na GBM

Preko 100 s glede na LAT

Izgleda kot afterglow (zasij)

Ackermann et al., 2010



3(7(*)M"

3(*(6)(

3(*(*('

3)((N)N

Svetlobna krivulja

Fluks pada potencno s casom

Tipicen α ∼ −1.5

Vcasih opazimo zlome

Spekter

Ne opazimo spektralne evolucije

Spektralni indeks β ∼ −2


Spektralne lastnosti LAT

Spektralni indeks β potencnega zakona za LAT GRB-je je skoraj enak.


GRB 090510 - dodatna potencna komponenta

Band fukncija + dodatna potencna komponenta:

Casovni potek spektra kaze rast potencne komponente!


Dodatna potencna komponenta

Dodatna potencna komponenta opazna se v nekaterih GRB-jih (npr. GRB 090902B):

Razteza se od zelo majhnih do zelo visokih energij, brez prekinitve.


GRB 090926A - Dodatna potencna komponenta

Band fukncija + dodatna potencna komponenta:


GRB 100724B - dodatna termicna komponenta

Band funkcija + BB (kT ≈ 38 keV):

Zelo sibka komponenta (torej zelo malo termicnih fotonov).


Lorentzov faktor izbruha

Lorentzovi faktorji nekaterih LAT GRB-jev z znanim z: Dolocitev temelji na spektru

+

Uposteva izotropno incasovno neodvisno

fotonsko polje

Bolj realisticno modeliranje(Granot 2008)

vrne manjse vrednosti.

Izmerjena vrednost zaGRB 090926A:Γ ∼ 200− 700


Energijske razlike med kratkimi in dolgimi GRB-ji

%

&;()(*#<6)*55.

Izmed 375 GBM izbruhov jih je okrog 50%v polju detektorja LAT:

Primerljivi izsevi za kratke GRB-je za visoke in nizke energije.Dolgi GRBji izsevajo ∼ 5− 20 krat manj pri visokih energijah kot pri nizkih.

LAT v povprecju detektira le najsvetljese GBM izbruhe.


Zakasnitev HE emisije 1/2

Krsitev Lorentzove invariance: vph(Eph) 6= c(H. F.-W. Sadrozinski, ponedeljkov fizikalni kolokvij 18.10.2010)

p2phc2

E2ph

− 1 =∞∑

k=1

sk

(Eph

MQG,kc2

)k

vph =∂Eph

∂pph≈ c

[1− sn

n+ 1

2

(Eph

MQG,nc2

)n ]

HE foton lahko pride pred (ce vph < c) ali za (ce vph > c) LE fotonom.

∆t = sn(1 + n)

2H0

(Enh −En

l )

(MQG,nc2)n

∫ z

0

(1 + z′)n√Ωm(1 + z′)3 +ΩΛ

dz′

LAT je najbolj obcutljiv na linearni clen n = 1.Iz tega lahko dobimo spodnjo limito za MQG, ki je reda velikosti MPlanck

tstart limit on Reason for choice of El valid lower limit on(ms) |∆t| (ms) tstart or limit on ∆t (MeV) for sn MQG,1/MPlanck

−30 < 859 start of any observed emission 0.1 1 > 1.19530 < 299 start of main < 1MeV emission 0.1 1 > 3.42630 < 199 start of > 100 MeV emission 100 1 > 5.12730 < 99 start of > 1 GeV emission 1000 1 > 10.0

— < 10 association with < 1MeV spike 0.1 ± 1 > 102— < 19 if 0.75GeV γ is from 1st spike 0.1 ± 1 > 1.33

| ∆t∆E| < 30 ms

GeVlag analysis of all LAT events — ± 1 > 1.22

GRB 090510


Zakasnitev HE emisije 2/2

First evidence for a gravitational lensing-induced echo ingamma rays with Fermi LAT

A. Barnacka2,1, J-F.Glicenstein1, and Y. Moudden1

1 DSM/IRFU, CEA/Saclay, F-91191 Gif-sur-Yvette, France2 Nicolaus Copernicus Astronomical Center, Warszawa, Poland

Preprint online version: November 22, 2010

ABSTRACT

Aims. This article shows the first evidence for gravitational lensing phenomena in high energy gamma-rays. This evidence comesfrom the observation of a gravitational lens induced echo in the light curve of the distant blazar PKS 1830-211.Methods. Traditional methods for the estimation of time delays in gravitational lensing systems rely on the cross-correlation of thelight curves of the individual images. In this paper, we use 300 MeV-30 GeV photons detected by the Fermi-LAT instrument. TheFermi-LAT instrument cannot separate the images of known lenses. The observed light curve is thus the superposition of individualimage light curves. The Fermi-LAT instrument has the advantage of providing long, evenly spaced, time series. In addition, the photonnoise level is very low. This allows to use directly Fourier transform methods.Results. A time delay between the two compact images of PKS 1830-211 has been searched for both by the autocorrelation methodand the “double power spectrum” method. The double power spectrum shows a 3 σ evidence for a time delay of 27.5±1.3 days,consistent with the result from Lovell et al. (1998). The relative uncertainty on the time delay estimation is reduced from 20% to 5%.

Key words. Gravitational lensing: strong – [Galaxies] quasars: individual: PKS 1830-211 – Methods: data analysis



Centralni izvor ali afterglow?

A LEPTONIC-HADRONIC MODEL FOR THE AFTERGLOW OF GAMMA-RAY BURST 090510

Soebur Razzaque1,2

Draft version October 6, 2010

ABSTRACT

We model multiwavelength afterglow data from the short Gamma-Ray Burst (GRB) 090510 usinga combined leptonic-hadronic model of synchrotron radiation from an adiabatic blast wave. Highenergy, & 100 MeV, emission in our model is dominated by proton-synchrotron radiation, whileelectron-synchrotron radiation dominates in the X ray and ultraviolet wavelengths. The collimation-corrected GRB energy, depending on the jet-break time, in this model could be as low as 3× 1051 ergbut two orders of magnitude larger than the absolute γ ray energy. We also calculated the opacitiesfor electron-positron pair production by γ rays and found that TeV γ rays from proton-synchrotronradiation can escape the blast wave at early time, and their detection can provide evidence of ahadronic emission component dominating at high energies.

Subject headings: gamma-ray burst: individual (GRB090510) – relativistic processes – shock waves

10-1

100

101

102

103

104

105

T - T0 (s)

10-11

10-10

10-9

10-8

10-7

10-6

10-5

10-4

10-3

10-2

10-1

Flu

x (

Jy)

XRTUVOTLATBATGBM Fig. 1.— Modeling of GRB 090510 light curves with proton-

synchrotron (solid lines) and electron-synchrotron (dashed lines)radiation from an adiabatic blast wave decelerating in a uniformdensity medium. The model light curves are computed at 100 MeV(black), 15 keV (green), 1 keV (red) and 3 eV (magenta) to becompared with the LAT, BAT, XRT and UVOT data points, re-spectively. The onset of the model light curves is at . T0 + 0.3 sfor Γ0 & 2400 for a surounding medium density of n = 3 cm−3.The other model parameters are Ek,iso = 2× 1055 erg, ǫe ≈ 10−4,ǫp ≈ 0.5, ǫB = 0.3. See main text for more details.


Tri spektralne komponente

Band funckija + BB (termicni spekter) + PL (potencni zakon)

Razlaga

BandDominira Poyntingov fluks (ICMART∗ model);Zhang & Pe‘er 2009, Zhang & Yan 2010∗Internal Collision-induced MAgnetic Reconnection and Turbulence model

BBTermicna emisija iz fotosfere ognjene krogle, ko relativisticni izbruh postane opticnotanek;Paczynski 1986, Goodman 1986, Pe‘er 2006, Pe‘er & Ryde 2010

PLV teoriji ga ne pricakujemo, sploh ne pri GeV energijah;


Velik Lorentzov faktor

Obstajajo modeli, kjer je mozen:

VERY HIGH LORENTZ FACTOR FIREBALLS AND GAMMA-RAY BURST SPECTRA

KUNIHITO IOKAKEK Theory Center and the Graduate University for Advanced Studies (Sokendai), Tsukuba 305-0801, Japan

Draft version November 2, 2010

ABSTRACT

Collisionless entrainment of the surroundingmatter imports the relativistic baryon component in the Gamma-Ray Burst (GRB) fireball frame. We show that half the fireball energy can be transferred from radiation to thecomoving hot motions of baryons under the photosphere. The yet baryon-poor fireball can reexpand to a

very high Lorentz factor (VHLF) Γ∼ 103–106 by its own relativistic collisionless pressure beyond the photo-sphere (so-called collisionless bulk acceleration), leading to internal and external shocks. A simple synchrotronemission from the VHLF internal shocks produces (i) the extra power-law spectral component with variabilityobserved in the Fermi GeV bursts, up to the TeV range for the future Cherenkov Telescope Array (CTA), (ii) the

GeV onset delay with a weak luminosity dependence tdelay ∼ L−1/5, and (iii) the spectral break of GRB 090926by the synchrotron cooling break or the maximum synchrotron cutoff limited by the dynamical time, not bythe e± creation cutoff. The relativistic baryon component could also heat the photospheric thermal photonsinto the main GRB Band spectrum via pp, pγ (Bethe-Heitler and photomeson), and Coulomb thermalizationprocesses. In this hot photosphere–internal–external shock model, we can predict the anticorrelation of ∼TeVneutrinos and GeV γ-rays, which may be detectable using IceCube. The spectral peak and luminosity (Yone-toku) relation is also reproduced if the progenitor stars are nearly identical. We also discuss the steep/shallowdecay of early X-ray afterglows and short GRBs.

Subject headings: gamma rays: bursts — gamma rays: theory — radiation mechanism: non-thermal


Zakljucek

Do danes je nase razumevanje izbruhov γ zarkov nepopolno.

Prevec je modelov, ki imajo zelo majhno napovedno moc.

Izziv za prihodnost.

Hvala!

Slike in podatki so vecinoma dobljeni iz razlicnih predstavitev na konferenci GRB 2010. Avtorji:

Michael Briggs, Valerie Connaughton, Sylvain Guiriec, Julie McEnery, Veronique Pelassa, Frederic Piron, Soeb

Razzaque, Vlasios Vasileiou.


Zakljucek

Do danes je nase razumevanje izbruhov γ zarkov nepopolno.

Prevec je modelov, ki imajo zelo majhno napovedno moc.

Izziv za prihodnost.

Hvala!

Slike in podatki so vecinoma dobljeni iz razlicnih predstavitev na konferenci GRB 2010. Avtorji:

Michael Briggs, Valerie Connaughton, Sylvain Guiriec, Julie McEnery, Veronique Pelassa, Frederic Piron, Soeb

Razzaque, Vlasios Vasileiou.

Dodatni material

Notranjost satelita Fermi

LAT

(high-E spectrum)

12 NaIs

(location & low-E spectrum)

2 BGOs

(mid-E spectrum)

GBM

BGO detektorji

12 NaIs(location &

low-E spectrum)

2 BGOs(mid-E spectrum)

GBM

2 Bismuth Germanate Detectors

• Diameter: 12.7 cm (5” x 5”)• Thickness: 12.7 cm (5”)• Energy range: ~200 keV – ~40 MeV

Primerjava med satelitoma Fermi in BATSE

100 ms27 usDeadtime per event

0.4 sr>2.2 srField of view

0.54°0.15°Angular resolution (single photon, 10 GeV) !

1500 cm29000 cm2Peak effective area

10%<10%Energy resolution (on axis, 100 MeV – 10 GeV)!

20 MeV – 30 GeV20 MeV to >300 GeVEnergy range

EGRETLAT

Instrument details:Meegan et al. 2009 ApJ 702 p.791

Primerjava med LAT T90 in GBM T90

Izracun Lorentzovega faktorja

8

%%%% Opacity and Bulk Opacity and Bulk Lorentz Lorentz FactorFactor

" ## (E = Emax ) =1$% =%min

Numerical calculation of opacity forNumerical calculation of opacity for ee++ee–– pair production opacitypair production opacity

target photontarget photon

distributiondistribution

Assumption:Assumption:

High-energy and targetHigh-energy and target

photons from the samephotons from the same

iinternal shocks with radiusnternal shocks with radius

RR ~ ~ &&22ctctvv

Minimum bulk Minimum bulk Lorentz Lorentz factorfactor

AnalyticAnalyticcalculation with acalculation with adelta-functiondelta-functionapproximation forapproximation forthe cross-sectionthe cross-sectionand for Bandand for Bandspectrumspectrum

Band spectrumBand spectrum

Gould &Gould &

Shreder Shreder 19661966

Documents

tudij izbruhov sevanja gama v dobi satelita Fermidunja/AD/presentations/AD...Uvod Detekcija Opazovanja Teorija in diskusijaZaklju cek Studij izbruhov sevanja gama v dobi satelita Fermi