8 research outputs found
Scaler mode of the Auger Observatory and Sunspots
Recent data from the Auger Observatory on low energy secondary cosmic ray
particles are analyzed to study temporal correlations together with data on the
daily sunspot numbers and neutron monitor data. Standard spectral analysis
demonstrates that the available data shows 1/f^{\beta} fluctuations with
{\beta} approximately 1 in the low frequency range. All data behave like
Brownian fluctuations in the high frequency range. The existence of long-range
correlations in the data was confirmed by detrended fluctuation analysis. The
real data confirmed the correlation between the scaling exponent of the
detrended analysis and the exponent of the spectral analysis.Comment: 20 pages, 6 figures, to be published in Astrophysical Journal
Supplement Serie
Searching for a Correlation Between Cosmic-Ray Sources Above 10^{19} eV and Large-Scale Structure
We study the anisotropy signature which is expected if the sources of ultra
high energy, >10^{19} eV, cosmic-rays (UHECRs) are extragalactic and trace the
large scale distribution of luminous matter. Using the PSCz galaxy catalog as a
tracer of the large scale structure (LSS), we derive the expected all sky
angular distribution of the UHECR intensity. We define a statistic, that
measures the correlation between the predicted and observed UHECR arrival
direction distributions, and show that it is more sensitive to the expected
anisotropy signature than the power spectrum and the two point correlation
function. The distribution of the correlation statistic is not sensitive to the
unknown redshift evolution of UHECR source density and to the unknown strength
and structure of inter-galactic magnetic fields. We show, using this statistic,
that recently published >5.7x10^{19} eV Auger data are inconsistent with
isotropy at ~98% CL, and consistent with a source distribution that traces LSS,
with some preference to a source distribution that is biased with respect to
the galaxy distribution. The anisotropy signature should be detectable also at
lower energy, >4x10^{19} eV. A few fold increase of the Auger exposure is
likely to increase the significance to >99% CL, but not to >99.9% CL (unless
the UHECR source density is comparable or larger than that of galaxies). In
order to distinguish between different bias models, the systematic uncertainty
in the absolute energy calibration of the experiments should be reduced to well
below the current ~25%.Comment: 17 pages, 8 figures. v2: reference added, typos corrected, accepted
to JCA
Multi-messenger Observations of a Binary Neutron Star Merger
On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of 1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg at a luminosity distance of Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Msun. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at 40 Mpc) less than 11 hours after the merger by the One-Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over 10 days. Following early non-detections, X-ray and radio emission were discovered at the transient's position 9 and 16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. (Abridged
Multi-messenger observations of a binary neutron star merger
On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta
30th International Cosmic Ray Conference Search for Gamma Ray Bursts using the single particle technique at the
Abstract: The Pierre Auger Observatory, with an array of currently more than 1200 Cherenkov detectors filled with 12 m 3 of water, can detect the putative high energy emission of a GRB (photons down to a few hundreds of MeV) by the so-called “single particle technique”, through a coherent increase in the average background particle rates over the whole array, due to secondary particles in the photon-induced showers. We present a search for bursts on data collected since September 2005, as well as a search for excesses in coincidence with bursts observed by satellites
Tunka-Rex: a Radio Extension of the Tunka Experiment
Tunka-Rex, the Tunka radio extension, is an array of about 20 antennas currently under construction, which covers an area of 1 km2. Tunka-Rex measures the radio emission of cosmic-ray air showers above 1016 eV. It is triggered by the photomultipliers of the Tunka-133 experiment which simultaneously measure the Cherenkov light emitted by the same air showers. The radio-Cherenkov-hybrid measurements thus offer a unique opportunity for a cross-calibration of both detection methods. The main goal of Tunka-Rex is to determine the precision of the radio reconstruction for the energy and the atmospheric depth of the shower maximum, Xmax, and thus to experimentally test theoretical predictions that the radio precision can be similar to the precision of air-Cherenkov and fluorescence measurements. At the same time, Tunka-Rex can demonstrate that radio measurements can be performed on a large area for a relatively cheap price, since the antennas will be connected to the already existing Tunka DAQ. Finally, radio-antenna arrays have the perspective to increase the effective observation time compared to air-Cherenkov and fluorescence detectors by an order of magnitude, since radio measurements are possible under almost any atmospheric and light conditions
Radio Measurements of Air Showers with LOPES
Contains fulltext :
117189.pdf (publisher's version ) (Open Access