Light speed variation from GRB 221009A

2025-05-04 0 0 396.61KB 5 页 10玖币

侵权投诉

Jie Zhua, Bo-Qiang Maa,b,c,∗

aSchool of Physics, Peking University, Beijing 100871, China

bCenter for High Energy Physics, Peking University, Beijing 100871, China

cCollaborative Innovation Center of Quantum Matter, Beijing, China

Abstract

It is postulated in Einstein’s relativity that the speed of light in vacuum is a constant for all observers. However, the eﬀect

of quantum gravity could bring an energy dependence of light speed, and a series of studies on high-energy photon events

from gamma-ray bursts (GRBs) and active galactic nuclei (AGNs) suggest a light speed variation v(E) = c(1 −E/ELV)

with ELV = 3.6×1017 GeV or a bound ELV ≥3.6×1017 GeV. From the newly observed gamma-ray burst GRB

221009A, we ﬁnd that a 99.3 GeV photon detected by Fermi-LAT is coincident with the sharp spike in the light curves

detected by both Fermi-GBM and HEBS under the above scenario of light speed variation, suggesting an option that

this high-energy photon was emitted at the same time as a sharp spike of low-energy photon emission at the GRB source.

Thus this highest energy photon event detected by Fermi-LAT during the prompt emission of gamma-ray bursts might

be considered as an optional signal for the linear form modiﬁcation of light speed in cosmological space.

Keywords:

gamma-ray burst, high-energy photon, light speed variation, Lorentz violation

On 9 October 2022, the Gamma-ray Burst Monitor

(GBM) [1] onboard the Fermi Gamma-ray Space Telescope

(FGST) triggered a special gamma-ray burst (GRB), num-

bered as GRB 221009A, at T0= 13 : 16 : 59.000 UT [2].

The prompt emission of this extraordinarily bright GRB

221009A was detected not only by Fermi [2–6], but also

by other space observatories such as Swift [7,8], AG-

ILE [9,10], INTEGRAL [11], Solar Orbiter [12], SRG [13],

Konus [14], GRBAlpha [15], STPSat-6 [16], HEBS [17],

and by ground observatories such as LHAASO [18] with

striking very-high-energy features [19]. This burst, located

at around RA = 288.282 and Dec = 19.495 [5], is a long

burst but with a very small redshift z= 0.1505 [20,21]

compared to most other long bursts. It is estimated that

there is only a 10% probability to observe an event like

GRB 221009A about 50 years after the discovery of the

ﬁrst GRB [22].

The Fermi Large Area Telescope (LAT) [23] also de-

tected this GRB. The highest energy photon observed by

LAT reaches 99.3 GeV (with a probability of 99.2%) [5],

and this photon event represents the highest GRB pho-

ton energy ever detected by Fermi-LAT during the prompt

emission phase of gamma-ray bursts. We show in this Let-

ter that such a high-energy photon event of Fermi-LAT

oﬀers a precious opportunity to explore the light speed

variation related with Lorentz violation (LV) [24].

It is speculated from quantum gravity that the Lorentz

∗Corresponding author

Email addresses: jiezhu@pku.edu.cn (Jie Zhu),

mabq@pku.edu.cn (Bo-Qiang Ma)

invariance might be broken at the Planck scale (EPl '

1.22 ×1019 GeV), and that the light speed may have a

variation with the energy of the photon. Amelino-Camelia

et al. [25,26] ﬁrst suggested testing Lorentz violation by

comparing the arrival times between high-energy and low-

energy photons from GRBs. For energy EEPl, the

modiﬁed dispersion relation of the photon can be expressed

in a model-independent way as

E2=p2c21−snpc

ELV,n n,(1)

from which we have the following speed relation

v(E) = c1−sn

n+ 1

2pc

ELV,n n,(2)

where n= 1 or n= 2 as usually assumed, sn=±1 indi-

cates whether high-energy photons travel faster (sn=−1)

or slower (sn= +1) than low-energy photons, and ELV,n

represents the nth-order Lorentz violation scale. Jacob

and Piran [27] suggested a formula of arrival-time diﬀer-

ence between astroparticles with diﬀerent energies as

∆tLV =sn

1 + n

2H0

h−En

LV,n Zz

(1 + z0)ndz0

pΩm(1 + z0)3+ ΩΛ

,(3)

where Ehand Elcorrespond to the energies of the ob-

served high-energy and low-energy photons, zis the red-

shift of the source GRB, H0, Ωmand ΩΛare cosmologi-

cal constants. Eq. (3) was derived in the standard model

of cosmology, and later was found the same as the time-

diﬀerence formula in expanding Finsler spacetime [28]. In

Preprint submitted to arXiv:2210.11376; Published in J. Phys. G: Nucl. Part. Phys. 50 (2023) 06LT01 May 17, 2023

arXiv:2210.11376v3 [astro-ph.HE] 16 May 2023

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摘要：

LightspeedvariationfromGRB221009AJieZhua,Bo-QiangMaa,b,c,aSchoolofPhysics,PekingUniversity,Beijing100871,ChinabCenterforHighEnergyPhysics,PekingUniversity,Beijing100871,ChinacCollaborativeInnovationCenterofQuantumMatter,Beijing,ChinaAbstractItispostulatedinEinstein'srelativitythatthespeedoflightinv...

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Light speed variation from GRB 221009A

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