共查询到20条相似文献，搜索用时 15 毫秒
1.
MAGIC is a system of two Imaging Atmospheric Cherenkov Telescopes located in the Canary island of La Palma, Spain. During summer 2011 and 2012 it underwent a series of upgrades, involving the exchange of the MAGIC-I camera and its trigger system, as well as the upgrade of the readout system of both telescopes. We use observations of the Crab Nebula taken at low and medium zenith angles to assess the key performance parameters of the MAGIC stereo system. For low zenith angle observations, the standard trigger threshold of the MAGIC telescopes is ∼ 50 GeV. The integral sensitivity for point-like sources with Crab Nebula-like spectrum above 220 GeV is (0.66 ± 0.03)% of Crab Nebula flux in 50 h of observations. The angular resolution, defined as the σ of a 2-dimensional Gaussian distribution, at those energies is ≲ 0.07°, while the energy resolution is 16%. We also re-evaluate the effect of the systematic uncertainty on the data taken with the MAGIC telescopes after the upgrade. We estimate that the systematic uncertainties can be divided in the following components: < 15% in energy scale, 11%–18% in flux normalization and ± 0.15 for the energy spectrum power-law slope. 相似文献
2.
D. Bastieri C. Bigongiari E. Bisesi G. Busetto A. De Angelis B. De Lotto T. Lenisa F. Longo M. Mariotti A. Moralejo D. Pascoli L. Peruzzo R. Rando A. Saggion P. Sartori V. Scalzotto 《Astroparticle Physics》2005,23(6):572-576
In this article we discuss the possibility of using the observations by GLAST of standard gamma sources, as the Crab Nebula, to calibrate imaging air Cherenkov detectors, MAGIC in particular, and optimise their energy resolution. We show that at around 100 GeV the absolute energy calibration uncertainty of Cherenkov telescopes can be reduced to 10% by means of such cross-calibration procedure. 相似文献
3.
Current imaging atmospheric Cherenkov telescopes for very high energy γ-ray astrophysics are pointing instruments with a field of view up to a few tens of sq deg. We propose to build an array of two non-steerable (drift) telescopes. Each of the telescopes would have a camera with a FOV of 5 × 60 sq deg oriented along the meridian. About half of the sky drifts through this FOV in a year. We have performed a Monte Carlo simulation to estimate the performance of this instrument. We expect it to survey this half of the sky with an integral flux sensitivity of ∼0.77% of the steady flux of the Crab Nebula in 5 years, an analysis energy threshold of ∼150 GeV and an angular resolution of ∼0.1°. For astronomical objects that transit over the telescope for a specific night, we can achieve an integral sensitivity of 12% of the Crab Nebula flux in a night, making it a very powerful tool to trigger further observations of variable sources using steerable IACTs or instruments at other wavelengths. 相似文献
4.
5.
F. Krennrich C.W. Akerlof J.H. Buckley J. Bussóns-Gordo D.A. Carter-Lewis M.F. Cawley M.A. Catanese V. Connaughton D.J. Fegan J.P. Finley J.A. Gaidos K.H. Harris A.M. Hillas R.C. Lamb M.J. Lang G. Mohanty J. Quinn A.J. Rodgers H.J. Rose A.C. Rovero M.S. Schubnell G.H. Sembroski T.C. Weekes C. Wilson 《Astroparticle Physics》1998,8(4):213-221
Observations of photons at E ≥ 550 GeV from the Crab Nebula are presented and used to assess the potential of multi-telescope systems for γ-ray astronomy.
The Whipple observatory 10 m and 8 m imaging atmospheric erenkov telescopes have been used to provide a stereoscopic view of air showers to make a more complete measurement of air shower parameters. Here we present a measurement of the spread in the arrival direction of primary γ-rays originating from a point source. The data show that the shower arrival direction can be reconstructed with an accuracy of σ = 0.°14. 相似文献
6.
W. Bednarek 《Monthly notices of the Royal Astronomical Society》2006,371(4):1737-1743
We apply an inverse Compton e ± pair cascade model for γ-ray production in the massive binary system LSI +61° 303 assuming that electrons are accelerated already inside the inner part of the jet launched by the compact object. γ-ray spectra, affected by the cascade process, and lower energy spectra, from the synchrotron cooling of the highest energy electrons in the jet, are calculated as a function of the phase of this binary system. γ-ray spectra expected in such a model have different shape than those ones produced by electrons in the jet directly to observer. Moreover, the model predicts clear anticorrelation between γ-ray fluxes in the GeV (1–10 GeV) and TeV (>200 GeV) energy ranges with the peak of the TeV emission at the phase ∼0.5 (the peak half-width ranges between the phases ∼0.4–0.9, for the inclination of the binary system equal to 60°, and ∼0.4–0.1 for 30°). The fine features of TeV γ-ray emission (fluxes and spectral shapes) as a function of the phase of the binary system are consistent with recent observations reported by the MAGIC collaboration. Future simultaneous observations in the GeV energies (by the GLAST and AGILE telescopes) and in the TeV energies (by the MAGIC and VERITAS telescopes) should test other predictions of the considered model supporting or disproving the hypothesis of acceleration of electrons already in the inner part of the microquasar jets. 相似文献
7.
It has been argued by Jacobson, Liberati and Mattingly that synchrotron radiation from the Crab Nebula imposes a stringent constraint on any modification of the dispersion relations of the electron that might be induced by quantum gravity. We supplement their analysis by deriving the spectrum of synchrotron radiation from the coupling of an electrically charged particle to an external magnetic fields in the presence of quantum-gravity effects of the general form (E/MQG). We find that the synchrotron constraint from the Crab Nebula practically excludes 1.74 for MQGmP=1.2×1019 GeV. On the other hand, this analysis does not constrain any modification of the dispersion relation of the photon that might be induced by quantum gravity. We point out that such quantum-gravity effects need not obey the equivalence principle, a point exemplified by the Liouville-string D-particle model of space–time foam. This model suggests a linear modification of the dispersion relation for the photon, but not for the electron, and hence is compatible with known constraints from the Crab Nebula and elsewhere. 相似文献
8.
A. Smith R. W. Atkins S. Bradbury O. Celik Y. C. K. Chow P. Cogan C. Dowdall S. J. Fegan P. Fortin D. Gall G. H. Gillanders J. Grube K. J. Gutierrez T. A. Hall D. Hanna J. Holder D. Horan S. B. Hughes T. B. Humensky I. Jung P. Kaaret G. Kenny M. Kertzman D. B. Kieda A. Konopelko H. Krawczynski F. Krennrich M. J. Lang S. Le Bohec G. Maier J. Millis P. Moriarty R. A. Ong J. S. Perkins K. Ragan G. H. Sembroski J. A. Toner L. Valcarcel V. V. Vassiliev R. G. Wagner S. P. Wakely T. C. Weekes R. J. White D. A. Williams 《Astrophysics and Space Science》2007,309(1-4):299-303
In this paper we present the results of the past two years observations on the galactic microquasar LS I +61 303 with the
Whipple 10 m gamma-ray telescope. The recent MAGIC detection of the source between 200 GeV and 4 TeV suggests that the source
is periodic with very high energy (VHE) gamma-ray emission linked to its orbital cycle. The entire 50-hour data set obtained
with Whipple from 2004 to 2006 was analyzed with no reliable detection resulting. The upper limits obtained in the 2005–2006
season covered several of the same epochs as the MAGIC Telescope detections, albeit with lower sensitivity. Upper limits are
placed on emission during the orbital phases of 0→0.1 and 0.8→1, phases which are not included in the MAGIC data set.
相似文献
9.
M. Lemoine-Goumard F. Aharonian D. Berge B. Degrange D. Hauser N. Komin O. Reimer U. Schwanke 《Astrophysics and Space Science》2007,309(1-4):379-384
In 2004 and 2005, the shell-type supernova remnants RX J1713.7–3946 and RX J0852.0–4622 were observed and detected with the
complete H.E.S.S. array, a system of four Imaging Cherenkov Telescopes located in Namibia and dedicated to the observations
of γ-rays above 100 GeV. The energy spectra of these two sources have been measured over a wide energy range and revealed an integral
flux above 1 TeV similar to that of the Crab Nebula. Their morphologies were resolved with high accuracy with H.E.S.S. and
exhibit a striking correlation with the X-ray images, thereby pioneering a technique of unambiguously identifying spatially
extended γ-ray sources. The results of the observations will be presented. Similarities and differences between these two sources will
be pointed out as well as possible implications.
M. Lemoine-Goumard, F. Aharonian, D. Berge, B. Degrange, D. Hauser, N. Komin, O. Reimer, U. Schwanke for the H.E.S.S. Collaboration 相似文献
10.
N. N. Kalinichenko 《Astrophysics and Space Science》2009,319(2-4):131-138
Interplanetary scintillation observations of eleven supernova remnants and the pulsar J1939+2134, around which the existence of a supernova remnant remains obscure, were carried out with the largest in the world decameter radio telescope UTR-2 at 20, 25 and 30 MHz to determine if any of them contain compact radio sources with the angular size θ<5″. The sample included the young Galactic remnants and the other powerful SNRs. The interplanetary scintillations of the compact radio source in the Crab Nebula associated with the well-known pulsar J0534+2200 and the pulsar J1939+2134 were observed. Apart from the Crab Nebula, we have not detected a compact radio source in supernova remnants with the angular size θ<5″ and the flux density more than 10 Jy. The observations do not confirm the existence of the low frequency compact source in Cassiopeia A that has remained controversial. 相似文献
11.
We present the spectral analysis system for the second-generation energetic X-ray imaging telescope experiment (EXITE2) balloon payload. EXITE2 is an imaging hard X-ray telescope using a coded-aperture mask and a NaI/CsI phoswich detector operating in the energy range 20–600 keV. The instrument was flown on a high-altitude scientific balloon from Ft. Sumner, NM on 7–8 May, 1997. We describe the details of the EXITE2 spectral analysis system, with emphasis on those aspects peculiar to coded-aperture instruments. In particular, we have made our analysis compatible with the standard X-ray spectral fitting package
by generating a response matrix in the appropriate format including all the effects of a coded-aperture system. The use of
, which may be a first for coded-aperture data, permits great flexibility in the fitting of spectral models. The additional effects of our phoswich system, or any other detector-specific considerations, may be easily included as well. We test our spectral analysis using observations of the Crab Nebula, and find that the EXITE2 Crab spectrum is consistent with those recorded by previous instruments operating in this energy range. 相似文献
12.
Yves A. Gallant 《Astrophysics and Space Science》2007,309(1-4):197-202
The H.E.S.S. array of imaging Cherenkov telescopes has discovered a number of previously unknown γ-ray sources in the very high energy (VHE) domain above 100 GeV. The good angular resolution of H.E.S.S. (∼0.1° per event),
as well as its sensitivity (a few percent of the Crab Nebula flux) and wide 5° field of view, allow a much better constrained
search for counterparts in comparison to previous instruments. In several cases, the association of the VHE sources revealed
by H.E.S.S. with pulsar wind nebulae (PWNe) is supported by a combination of positional and morphological evidence, multi-wavelength
observations, and plausible PWN model parameters. These include the plerions in the composite supernova remnants G 0.9+0.1
and MSH 15–52, the recently discovered Vela X nebula, two new sources in the Kookaburra complex, and the association of HESS J1825–137
with PSR B1823–13. The properties of these better-established associations are reviewed. A number of other sources discovered
by H.E.S.S. are located near high spin-down power pulsars, but the evidence for association is less complete. These possible
associations are also discussed, in the context of the available multi-wavelength data and plausible PWN scenarios.
For the H.E.S.S. Collaboration 相似文献
13.
14.
V. V. Fidelis A. A. Stepanian V. S. Eliseev N. A. Zhogolev E. M. Nekhai Yu. I. Neshpor Z. N. Skiruta 《Astronomy Letters》2005,31(9):575-578
The galaxy Mrk 421 was observed with the GT-48 Cherenkov telescope in 2004. The observations revealed a very-high-energy gamma-ray flux at a confidence level of 4.8 σ. Comparison with the constant gamma-ray flux from the Crab Nebula yielded an estimate of the total flux from Mrk 421, 1.7 ± 0.7 Crab (E ≥ 1 TeV). 相似文献
15.
P. R. Vishwanath 《Journal of Astrophysics and Astronomy》2002,23(1-2):45-51
The field of Very High Energy (VHE) gamma ray astronomy using the Atmospheric Cerenkov Technique has entered an interesting
phase with detection of various galactic and extragalactic sources. Among galactic sources, only the Crab nebula has been
established as a standard candle. Most observations on pulsars are in agreement as to the necessity for the GeV spectra to
steepen at < 200 GeV. While the Imaging method for increase of sensitivity has been successful with many results, an alternate
technique —Wavefront Sampling Technique- is also being used by an increasing number of experiments. The recently commissioned experiment at Pachmarhi (PACT) in India
is presented as an example of this technique. Preliminary results from this experiment show detection of VHE γ-ray emission
from (a) the Crab nebula at a high significance and (b) Crab and Geminga pulsars at > 1.5 TeV which could be the second component of the Outer Gap pulsar models. 相似文献
16.
The Chandra X-Ray Observatory observed the Crab Nebula and pulsar during orbital calibration. Zeroth-order images with the High-Energy Transmission Grating (HETG) readout by the Advanced CCD Imaging Spectrometer spectroscopy array (ACIS-S) show a striking richness of X-ray structure at a resolution comparable to that of the best ground-based visible-light observations. The HETG-ACIS-S images reveal, for the first time, an X-ray inner ring within the X-ray torus, the suggestion of a hollow-tube structure for the torus, and X-ray knots along the inner ring and (perhaps) along the inward extension of the X-ray jet. Although complicated by instrumental effects and the brightness of the Crab Nebula, the spectrometric analysis shows systematic variations of the X-ray spectrum throughout the nebula. 相似文献
17.
Based on the half-century-long history of radio observations of the Crab Nebula, we investigate the evolution of its radio luminosity. We found a secular decrease in the radio luminosity; it has decreased by 9% since the discovery of the radio source in 1948. Apart from the secular decrease in the luminosity of the Crab Nebula, we identified two time intervals, 1981–1987 and 1992–1998, when radio bursts with energy release ～1041 erg took place. In these years, the spectral indices of the instantaneous spectra decreased significantly due to the increase in the flux densities at short (centimeter and millimeter) wavelengths. These events were preceded by sudden increases in the pulsar’s rotation rates, the largest of which, with an amplitude of ΔΩ/Ω = 3 × 10?8, occurred in 1975 and 1989. We show that the magnetospheric instability mechanism that accompanies strong glitches can provide the energetics of the excess luminosity of the Nebula through the ejection of relativistic electrons with a total energy higher than 6 × 1042 erg from the pulsar’s magnetosphere. 相似文献
18.
V. V. Fidelis 《Bulletin of the Crimean Astrophysical Observatory》2011,107(1):20-24
The observational data concerning variations of light curves of supernovae remnants—the Crab Nebula, Cassiopeia A, Tycho Brahe,
and pulsar Vela—over 14 days scale that may be attributed to systematic errors of the ASM/RXTE monitor are presented. The
experimental systematic errors of the GT-48 γ-ray telescope in the mono mode of operation were also determined. For this the
observational data of TeV J2032 + 4130 (Cyg γ-2, according to the Crimean version) were used and the stationary nature of
its γ-ray emission was confirmed by long-term observations performed with HEGRA and MAGIC. The results of research allow us
to draw the following conclusions: (1) light curves of supernovae remnants averaged for long observing periods have false
statistically significant flux variations, (2) the level of systematic errors is proportional to the registered flux and decreases
with increasing temporal scale of averaging, (3) the light curves of sources may be modulated by the year period, and (4)
the systematic errors of the GT-48 γ-ray telescope, in the amount caused by observations in the mono mode and data processing
with the stereo-algorithm come to 0.12 min−1. 相似文献
19.
We present the results of our observations of two types of Galactic supernova remnants with the ShALON mirror Cherenkov telescope:
the plerion Crab Nebula and the shell-type supernova remnants Cassiopeia A and Tycho. The experimental data have confirmed
the prediction of the theory about the hadronic generation mechanism of very high energy (0.8–100 TeV) gamma rays in Tycho’s
supernova remnant. The data obtained suggest that the very high energy gamma-ray emission in the objects being discussed is
different in origin. 相似文献
20.
Wallace H. Tucker 《Astrophysics and Space Science》1970,9(2):315-331
General models for the secular behavior of the radio and X-ray emission from supernova remnants are examined and compared with the observations. Hot plasma and synchrotron models for the X-ray emission are considered. Among other things, it is concluded that (1) the total kinetic energy released in most supernova outbursts is probably less than about 1051 ergs; (2) continuous injection probably occurs for at least 10 yr in every case and about 1000 yr in most supernova remnants, in which case the supernova remnants 3C392, W28, Pup A and IC443 should produce 1–10 keV X-ray fluxes 10–10 ergs/cm2 sec; and (3) the X-ray sources in the Crab Nebula, Cas A and Tycho can be explained in terms of a model wherein continuous injection occurs for 300 yr for the Crab Nebula, much less than 250 yr for Cas A and much longer than 400 yr for Tycho. Finally, it is shown that if Tycho and Cas A contain an X-ray star such as NP0532, it is quite possible that the X-ray emission from those sources is predominantly due to the X-ray star.Supported by the Air Force Office of Scientific Research under Contract No. F44620-67-C-0065. 相似文献