Cosmic rays are energetic charged particles from extraterrestrial sources, with the highest-energy events thought to come from extragalactic sources. Their arrival is infrequent, so detection ...requires instruments with large collecting areas. In this work, we report the detection of an extremely energetic particle recorded by the surface detector array of the Telescope Array experiment. We calculate the particle’s energy as
244
±
29
stat
.
−
76
+
51
syst
.
exa–electron volts
(~40 joules). Its arrival direction points back to a void in the large-scale structure of the Universe. Possible explanations include a large deflection by the foreground magnetic field, an unidentified source in the local extragalactic neighborhood, or an incomplete knowledge of particle physics.
Editor’s summary
Cosmic rays are charged particles from space. At low energies, they mostly originate from the Sun, whereas at high energies, they are expected to be emitted by nearby active galaxies. The Telescope Array Collaboration now reports the detection of a cosmic ray event with an energy of about 240 exa–electron volts, more than a million times higher than that achieved by artificial particle accelerators. Such high-energy particles should experience only small deflections by foreground magnetic fields, but tracing back the arrival direction shows no obvious source galaxy. The authors suggest that the foreground magnetic fields might be stronger than expected, or there could be unknown particle physics at high energies. —Keith T. Smith
Detection of a highly energetic cosmic ray is traced back to its arrival direction, but no source galaxy is evident.
Some Like It Hot (review) Furlich, Emily G
Theatre Journal,
12/2023, Letnik:
75, Številka:
4
Journal Article, Book Review
Recenzirano
Joe, played by Christian Borle, and Jerry, played by Black non-binary actor J. Harrison Ghee, escape the gangsters tracking them down in Chicago by disguising themselves as women and joining an ...integrated, all-women band heading to California. The musical begins with Sweet Sue (NaTasha Yvette Williams), the band’s Black manager, singing in a speakeasy. See PDF Jerry, now going by Daphne, a name they pointedly chose over the feminine version of Jerry (Geraldine) that Joe suggested, makes fast friends with the women in the band and admires their new look in a mirror. Daphne’s gender exploration continues when the band arrives in California and they meet Osgood, refigured by López and Ruffin as a Mexican American businessman. ...a figure in a dress cornered the head gangster.
We report an estimation of the injected mass composition of ultrahigh energy cosmic rays (UHECRs) at energies higher than 10 EeV. The composition is inferred from an energy-dependent sky distribution ...of UHECR events observed by the Telescope Array surface detector by comparing it to the Large Scale Structure of the local Universe. In the case of negligible extragalactic magnetic fields (EGMFs), the results are consistent with a relatively heavy injected composition at E∼10 EeV that becomes lighter up to E∼100 EeV, while the composition at E>100 EeV is very heavy. The latter is true even in the presence of highest experimentally allowed extragalactic magnetic fields, while the composition at lower energies can be light if a strong EGMF is present. The effect of the uncertainty in the galactic magnetic field on these results is subdominant.We report an estimation of the injected mass composition of ultrahigh energy cosmic rays (UHECRs) at energies higher than 10 EeV. The composition is inferred from an energy-dependent sky distribution of UHECR events observed by the Telescope Array surface detector by comparing it to the Large Scale Structure of the local Universe. In the case of negligible extragalactic magnetic fields (EGMFs), the results are consistent with a relatively heavy injected composition at E∼10 EeV that becomes lighter up to E∼100 EeV, while the composition at E>100 EeV is very heavy. The latter is true even in the presence of highest experimentally allowed extragalactic magnetic fields, while the composition at lower energies can be light if a strong EGMF is present. The effect of the uncertainty in the galactic magnetic field on these results is subdominant.
We use a new method to estimate the injected mass composition of ultrahigh cosmic rays (UHECRs) at energies higher than 10 EeV. The method is based on comparison of the energy-dependent distribution ...of cosmic ray arrival directions as measured by the Telescope Array experiment (TA) with that calculated in a given putative model of UHECR under the assumption that sources trace the large-scale structure (LSS) of the Universe. As we report in the companion letter, the TA data show large deflections with respect to the LSS which can be explained, assuming small extra-galactic magnetic fields (EGMF), by an intermediate composition changing to a heavy one (iron) in the highest energy bin. Here we show that these results are robust to uncertainties in UHECR injection spectra, the energy scale of the experiment and galactic magnetic fields (GMF). The assumption of weak EGMF, however, strongly affects this interpretation at all but the highest energies E > 100 EeV, where the remarkable isotropy of the data implies a heavy injected composition even in the case of strong EGMF. This result also holds if UHECR sources are as rare as \(2 \times 10^{-5}\) Mpc\(^{-3}\), that is the conservative lower limit for the source number density.
We report on an observation of the difference between northern and southern skies of the ultrahigh energy cosmic ray energy spectrum with a significance of \({\sim}8\sigma\). We use measurements from ...the two largest experiments\(\unicode{x2014}\)the Telescope Array observing the northern hemisphere and the Pierre Auger Observatory viewing the southern hemisphere. Since the comparison of two measurements from different observatories introduces the issue of possible systematic differences between detectors and analyses, we validate the methodology of the comparison by examining the region of the sky where the apertures of the two observatories overlap. Although the spectra differ in this region, we find that there is only a \(1.8\sigma\) difference between the spectrum measurements when anisotropic regions are removed and a fiducial cut in the aperture is applied.
We report an estimation of the injected mass composition of ultra-high energy
cosmic rays (UHECRs) at energies higher than 10 EeV. The composition is
inferred from an energy-dependent sky ...distribution of UHECR events observed by
the Telescope Array surface detector by comparing it to the Large Scale
Structure of the local Universe. In the case of negligible extra-galactic
magnetic fields the results are consistent with a relatively heavy injected
composition at E ~ 10 EeV that becomes lighter up to E ~ 100 EeV, while the
composition at E > 100 EeV is very heavy. The latter is true even in the
presence of highest experimentally allowed extra-galactic magnetic fields,
while the composition at lower energies can be light if a strong EGMF is
present. The effect of the uncertainty in the galactic magnetic field on these
results is subdominant.
In this paper, we present the first high-speed video observation of a cloud-to-ground lightning flash and its associated downward-directed Terrestrial Gamma-ray Flash (TGF). The optical emission of ...the event was observed by a high-speed video camera running at 40,000 frames per second in conjunction with the Telescope Array Surface Detector, Lightning Mapping Array, interferometer, electric-field fast antenna, and the National Lightning Detection Network. The cloud-to-ground flash associated with the observed TGF was formed by a fast downward leader followed by a very intense return stroke peak current of -154 kA. The TGF occurred while the downward leader was below cloud base, and even when it was halfway in its propagation to ground. The suite of gamma-ray and lightning instruments, timing resolution, and source proximity offer us detailed information and therefore a unique look at the TGF phenomena.
We present the first observation by the Telescope Array Surface Detector (TASD) of the effect of thunderstorms on the development of cosmic ray single count rate intensity over a 700 km\(^{2}\) area. ...Observations of variations in the secondary low-energy cosmic ray counting rate, using the TASD, allow us to study the electric field inside thunderstorms, on a large scale, as it progresses on top of the 700 km\(^{2}\) detector, without dealing with the limitation of narrow exposure in time and space using balloons and aircraft detectors. In this work, variations in the cosmic ray intensity (single count rate) using the TASD, were studied and found to be on average at the \(\sim(0.5-1)\%\) and up to 2\% level. These observations were found to be both in excess and in deficit. They were also found to be correlated with lightning in addition to thunderstorms. These variations lasted for tens of minutes; their footprint on the ground ranged from 6 to 24 km in diameter and moved in the same direction as the thunderstorm. With the use of simple electric field models inside the cloud and between cloud to ground, the observed variations in the cosmic ray single count rate were recreated using CORSIKA simulations. Depending on the electric field model used and the direction of the electric field in that model, the electric field magnitude that reproduces the observed low-energy cosmic ray single count rate variations was found to be approximately between 0.2-0.4 GV. This in turn allows us to get a reasonable insight on the electric field and its effect on cosmic ray air showers inside thunderstorms.
Telescope Array (TA) is the largest experiment in the Northern Hemisphere studying ultrahigh energy cosmic rays. TA measurements of the cosmic ray spectrum using the surface detector have the best ...statistical power in the experiment, and observe the ankle of the spectrum and the high energy cutoff. When the data are divided into two declination bands, above and below 24.8 degrees, the cutoff appears at \(10^{19.64 \pm 0.04}\) (\(10^{19.84 \pm 0.02}\)) eV in the lower (higher) band, an energy difference of 58\%. The global significance of the difference is 4.3 standard deviations. The lack of an instrumental cause of this difference implies it is astrophysical in nature.
The Telescope Array Collaboration has observed an excess of events with \(E \ge 10^{19.4} ~{\rm eV}\) in the data which is centered at (RA, dec) = (\(19^\circ\), \(35^\circ\)). This is near the ...center of the Perseus-Pisces supercluster (PPSC). The PPSC is about \(70 ~{\rm Mpc}\) distant and is the closest supercluster in the Northern Hemisphere (other than the Virgo supercluster of which we are a part). A Li-Ma oversampling analysis with \(20^\circ\)-radius circles indicates an excess in the arrival direction of events with a local significance of about 4 standard deviations. The probability of having such excess close to the PPSC by chance is estimated to be 3.5 standard deviations. This result indicates that a cosmic ray source likely exists in that supercluster.
