A Search for Dark Matter Annihilation with the Whipple 10m Telescope
M. Wood, G. Blaylock, S. M. Bradbury, J. H. Buckley, K. L. Byrum, Y. C. K. Chow, W. Cui, I. de la Calle Perez, A. D. Falcone, S. J. Fegan, J. P. Finley, J. Grub… 展开作者
M. Wood, G. Blaylock, S. M. Bradbury, J. H. Buckley, K. L. Byrum, Y. C. K. Chow, W. Cui, I. de la Calle Perez, A. D. Falcone, S. J. Fegan, J. P. Finley, J. Grube, J. Hall, D. Hanna, J. Holder, D. Horan, T. B. Humensky, D. B. Kieda, J. Kildea, A. Konopelko, H. Krawczynski, F. Krennrich, M. J. Lang, S. LeBohec, T. Nagai, R. A. Ong, J. S. Perkins, M. Pohl, J. Quinn, H. J. Rose, G. H. Sembroski, V. V. Vassiliev, R. G. Wagner, S. P. Wakely, T. C. Weekes, A. Weinstein
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33 pages, 12 figures, accepted for publication in the Astrophysical Journal
We present observations of the dwarf galaxies Draco and Ursa Minor, the local group galaxies M32 and M33, and the globular cluster M15 conducted with the Whipple 10m gamma-ray telescope to search for the gamma-ray signature of self-annihilating weakly interacting massive particles (WIMPs) which may constitute astrophysical dark matter (DM). We review the motivations for selecting these sources based on their unique astrophysical environments and report the results of the data analysis which produced upper limits on excess rate of gamma rays for each source. We consider models for the DM distribution in each source based on the available observational constraints and discuss possible scenarios for the enhancement of the gamma-ray luminosity. Limits on the thermally averaged product of the total self-annihilation cross section and velocity of the WIMP, <σv>, are derived using conservative estimates for the magnitude of the astrophysical contribution to the gamma-ray flux. Although these limits do not constrain predictions from the currently favored theoretical models of supersymmetry (SUSY), future observations with VERITAS will probe a larger region of the WIMP parameter phase space, <σv> and WIMP particle mass (m_χ).
The Whipple 10 meter atmospheric Cherenkov telescope has made observations of the region known as the Cygnus arm. This region has been recently reported by the Milagro experiment to contain a diffuse TeV gamma-ray source centered at RA=308 and Dec=42. We report upper limits (using the Whipple 10 m telescope) obtained during the Fall 2004 observing season centered on RA=310 and Dec=42.65.
The Whipple 10-m telescope was used to observe M87 since 2000. No significant gamma-ray signal was found and upper limits compared to the HEGRA detection suggest the source may be variable. We found weak evidence for a correlation with the X-ray activity in 2000-2001 but this tendency did not persist in 2002-2003.
The BL Lacertae object H1426+428 is the most distant, confirmed source of TeV gamma rays. At a redshift of 0.129, its detection at TeV energies has important implications for estimating the density of the extragalactic infra-red background radiation. H1426+428 was observed extensively during the 2001/2002 observing season with the Whipple 10 m gamma-ray telescope. The results of these observations are presented here and are combined with the results of previous observations made between 1999 and 2001 at Whipple.
In September 2005, the observing program of the Whipple 10 m gamma-ray telescope was redefined to be dedicated almost exclusively to AGN monitoring. Since then the five Northern Hemisphere blazars that had already been detected at Whipple are monitored routinely each night that they are visible. Thanks to the efforts of a large number of multiwavelength collaborators, the first year of this program has been very successful. We report here on the analysis of Markarian 421 observations taken from November, 2005 to May, 2006 in the gamma-ray, X-ray, optical and radio bands.
An all-sky survey performed with the Tibet Air Shower Array (Tibet AS) has found a number of potential point sources of TeV gamma rays. If they are steady sources, the implied Tibet AS fluxes should be visible with strong significance to the Whipple 10-m gamma-ray telescope (E > 400 GeV) with only a short (5 hour) exposure. We have observed four candidate directions from the Tibet-II HD dataset for ~5 hours each with the Whipple telescope. In addition, we observed a new candidate direction from the Tibet-III Phase 1 dataset for 7.5 hours. We have found no corresponding excesses at the flux lev…
We present the first strong detection of very high energy gamma-rays from the close (z=0.048) X-ray selected BL Lacertae object 1ES1959+650. Observations were made with the Whipple 10m telescope on Mt. Hopkins, Arizona, using the atmospheric Cherenkov imaging technique. The flux between May and July 2002 was highly variable, with a mean of 0.64 +/- 0.03 times the steady flux from the Crab Nebula and reaching a maximum of five Crab, with variability on timescales as short as seven hours.
A recent report from the Milagro collaboration included an all-sky map created using one year of data from Milagro (peak sensitivity at 3-4 TeV for Crab-like spectra). This map included an unidentified excess that was brighter than the Crab and was the second brightest spot on the map. The hot spot was within the error box of the EGRET unidentified source 3EG J0520+2556. No strong and steady emission was detected by the Whipple telescope at, or in the vicinity of, either position. The 95% confidence level flux upper limits from Whipple observations at the locations of the Milagro hot spot and …
In this paper we present the results of the past two years' observations on the galactic microquasar LS I +61 303 with the Whipple 10m 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 sensiti…
Strong flares of TeV gamma-ray emission up to a level of ~5 Crab were detected by the Whipple 10 m atmospheric Cerenkov telescope from the BL Lacertae object 1ES1959+650 during May - July 2002. We report here the results of follow up observations during 2002 - 2003.
We present the results of a search for pulsed TeV emission from the Crab pulsar using 97 hours of data recorded with the high-resolution GRANITE III camera of the Whipple 10 m gamma-ray telescope.
Due to the strong and steady TeV gamma-ray emission from the Crab Nebula supernova remnant, its measured flux and energy spectrum can be used to verify the calibration and data reduction methods applied to IACT data acquired over many observing seasons. This gives us confidence in the results obtained on variable TeV sources observed over the same period and in relating the sensitivity of new instruments to historical datasets. Here we present the results of an analysis of 65.3 hours of good quality data taken on the Crab Nebula between October 2000 and March 2006 with the Whipple 10m telescop…
The Whipple 10m Very High Energy gamma-ray telescope has been used to search for indications of WIMP annihilation in the direction of the globular cluster M15. The upper limits derived constrain the amount of super-symmetric dark matter that may reside in globular clusters.
We report on observations of the sky region around the unidentified TeV gamma-ray source TeV J2032+4130 carried out with the Whipple Observatory 10 m atmospheric Cherenkov telescope for a total of 65.5 hrs between 2003 and 2005. The standard two-dimensional analysis developed by the Whipple collaboration for a stand-alone telescope reveals an excess in the field of view at a pre-trials significance level of 6.1 standard deviations. The measured position of this excess is alpha(2000) =20 h 32 m 27 s, delta(2000) = 41 deg 39 min 17 s. The estimated integral flux for this gamma-ray source is abou…
Gamma-ray burst (GRB) observations at very high energies (VHE, E > 100 GeV) can impose tight constraints on some GRB emission models. Many GRB afterglow models predict a VHE component similar to that seen in blazars and plerions, in which the GRB spectral energy distribution has a double-peaked shape extending into the VHE regime. VHE emission coincident with delayed X-ray flare emission has also been predicted. GRB follow-up observations have had high priority in the observing program at the Whipple 10m Gamma-ray Telescope and GRBs will continue to be high priority targets as the next generat…
Blazars have traditionally been separated into two broad categories based upon their optical emission characteristics; BL Lacs, with faint or no emission lines, and flat spectrum radio quasars (FSRQs) with prominent, broad emission lines. The spectral energy distribution of FSRQs has generally been thought of as being more akin to the low-peaked BL Lacs, which exhibit a peak in the infrared region of the spectrum, as opposed to high-peaked BL Lacs (HBLs), which exhibit a peak in UV/X-ray region of the spectrum. All blazars currently confirmed as sources of TeV emission are HBLs. Recent surveys…
During the 2002-2003 observing season the Whipple 10m imaging atmospheric Cerenkov telescope was used to search for dark matter annihilation radiation in four nearby galaxies: M32, M33, Draco, and Ursa Minor. Scientific motivations for this choice of targets are discussed as well as accumulated exposure. The analysis results are to be reported in the conference presentation.
Context. The modern generation of Cherenkov telescopes has revealed a new population of gamma-ray sources in the Galaxy. Some of them have been identified with previously known X-ray binary systems while other remain without clear counterparts a lower energies. Our initial goal here was reporting on extensive radio observations of the first extended and yet unidentified source, namely TeV J2032+4130. This object was originally detected by the HEGRA telescope in the direction of the Cygnus OB2 region and its nature has been a matter of debate during the latest years. Aims. We aim to pursue our …
Many authors have predicted very-high-energy (VHE; E > 100 GeV) emission from gamma-ray bursts (GRBs) both during the prompt phase and during the multi-component afterglow. To date, however, there has been no definitive detection of such emission. Recently, the Swift Satellite made the exciting discovery that almost 50% of GRBs are accompanied by one or more X-ray flares, which are found to occur from several seconds to many hours after the prompt emission. The discovery of this phenomenon and the many predictions that VHE emission should accompany these flares increases the already strong mot…
The MAGIC collaboration has observed very high energy gamma ray emission from the AGN 1ES 2344+514. A gamma-ray signal corresponding to an 11 sigma excess and an integral flux of (2.38+-0.30(stat)+-0.70(syst))*10^-11 cm^-2 s^-1 above 200 GeV has been obtained from 23.1 hours of data taking between 2005 August 3 and 2006 January 1. The data confirm the previously detected gamma-ray emission from this object during a flare seen by the Whipple collaboration in 1995 and the evidence (below 5 sigma significance level) from long-term observations conducted by the Whipple and HEGRA groups. The MAGIC …
A reanalysis of data taken on the Cygnus region in 1989-90 using the Whipple Observatory atmospheric Cherenkov imaging telescope confirms the existence of the TeV J2032+4130 source reported by the Crimean Astrophysical Observatory and published by the HEGRA Collaboration. The significance at the a priori HEGRA position is 3.3sigma. The peak signal was found at RA=20hr32min, Dec=+41deg33min. This is 0.6deg north of Cygnus X-3 which was the original target of the observations. The flux level (12% of the level of the Crab Nebula) is intermediate between the two later observations and suggests tha…
The first VERITAS (Very Energetic Radiation Imaging Telescope Array System) telescope has been in operation at the basecamp of the Whipple Observatory since January 2005. Here we present initial observations of AGN made using this telescope. Although this is engineering data, significant detections of Markarian 421 and Markarian 501 have been achieved.
To date three plerionic systems have been detected as emitters of very energetic photons. As part of an ongoing study of pulsar systems at the Whipple observatory, observations of the plerion PSR B1823-13 are being conducted. Observations were made with the Whipple 10 m gamma-ray telescope utilizing the high resolution, 490 pixel camera.
The GRANITE III camera of the Whipple Cherenkov Telescope at the Fred Lawrence Whipple Observatory on Mount Hopkins, Arizona (2300 m a.s.l.) has the highest angular resolution of all cameras used on this telescope so far. The central region of the camera has 379 pixels with an individual angular diameter of 0.12 degrees. This makes the instrument especially suitable for observations of gamma-induced air-showers at large zenith angles since the increase in average distance to the shower maximum leads to smaller shower images in the focal plane of the telescope. We examine the performance of the…
The HEGRA gamma-ray source TeV J2032+4130 is considered the prototypical 'dark accelerator', since it was the first TeV source detected with no firm counterparts at lower frequencies. The Whipple collaboration observed this source in 2003-5 and the emission hotspot appears displaced about 9 arcminutes to the northeast of the HEGRA position, though given the large positional uncertainties the HEGRA and Whipple positions are consistent. Here we report on Westerbork Synthesis Radio Telescope (WSRT), Very Large Array (VLA), Chandra and INTEGRAL data covering the locations of the Whipple and HEGRA …
The Short GAmma Ray Front Air Cherenkov Experiment (SGARFACE) is operated at the Whipple Observatory utilizing the Whipple 10m gamma-ray telescope. SGARFACE is sensitive to gamma-ray bursts of more than 100MeV with durations from 100ns to 35us and provides a fluence sensitivity as low as 0.8 gamma-rays per m^2 above 200MeV (0.05 gamma-rays per m^2 above 2GeV) and allows to record the burst time structure.
Only BL Lac objects have been detected as extragalactic sources of very high energy (E > 300 GeV) gamma rays. Using the Whipple Observatory Gamma-ray Telescope, we have attempted to detect more BL Lacs using three approaches. First, we have conducted surveys of nearby BL Lacs, which led to the detections of Mrk 501 and 1ES 2344+514. Second, we have observed X-ray bright BL Lacs when the RXTE All-Sky Monitor identifies high state X-ray emission in an object, in order to efficiently detect extended high emission states. Third, we have conducted rapid observations of several BL Lacs and QSOs loca…
We report on observations of Markarian 421 made with the Whipple 10m Cerenkov telescope and the RXTE satellite during a multi-wavelength campaign in December 2002 and January 2003, initiated by a Whipple target of opportunity. The observations revealed several flares with flux levels between 1 and 2 times the flux of the Crab Nebula. We will discuss the temporal properties, including evidence of X-ray/TeV gamma-ray flux correlation.
Following the detection of strong TeV gamma-ray flares from the BL Lac object 1ES 1959+650 with the Whipple 10 m Cherenkov telescope on May 16 and 17, 2002, we performed intensive Target of Opportunity (ToO) radio, optical, X-ray and TeV gamma-ray observations from May 18, 2002 to August 14, 2002. Observations with the X-ray telescope RXTE and the Whipple and HEGRA gamma-ray telescopes revealed several strong flares, enabling us to sensitively test the X-ray/gamma-ray flux correlation properties. Although the X-ray and gamma-ray fluxes seemed to be correlated in general, we found an ``orphan''…
The idea of searching for optical signals from extraterrestrial civilizations has become increasingly popular over the last five years, with dedicated projects at a number of observatories. The method relies on the detection of a brief (few ns), intense light pulse with fast photon detectors. Ground-based gamma-ray telescopes such as the Whipple 10m, providing a large mirror area and equipped with an array of photomultiplier tubes (PMTs), are ideal instruments for this kind of observation if the background of cosmic-ray events can be rejected. We report here on a method for searching for optic…
We present photometry on 23 Jupiter Family Comets (JFCs) observed at large heliocentric distance, primarily using the 2.5m Isaac Newton Telescope (INT). Snap-shot images were taken of 17 comets, of which 5 were not detected, 3 were active and 9 were unresolved and apparently inactive. These include 103P/Hartley 2, the target of the NASA Deep Impact extended mission, EPOXI. For 6 comets we obtained time-series photometry and use this to constrain the shape and rotation period of these nuclei. The data are not of sufficient quantity or quality to measure precise rotation periods, but the time-se…
Our understanding of blazars has been greatly increased in recent years by extensive multi-wavelength observations, particularly in the radio, X-ray and gamma-ray regions. Over the past decade the Whipple 10m telescope has contributed to this with the detection of 5 BL Lacertae objects at very high gamma-ray energies. The combination of multi-wavelength data has shown that blazars follow a well-defined sequence in terms of their broadband spectral properties. Together with providing constraints on emission models, this information has yielded a means by which potential sources of TeV emission …
VERITAS is a system of four imaging Cherenkov telescopes located at the Fred Lawrence Whipple Observatory in southern Arizona. We present here results of detailed Monte Carlo simulations of the array response to extensive air showers. Cherenkov image and shower parameter distributions are calculated and show good agreement with distributions obtained from observations of background cosmic rays and high-energy gamma-rays. Cosmic-ray and gamma-ray rates are accurately predicted by the simulations. The energy threshold of the 3-telescope system is about 150 GeV after gamma-hadron separation cuts;…
Observations of unidentified EGRET sources were made with the Whipple 10m imaging atmospheric Cherenkov telescope between Fall 1999 and Spring 2001. During this period, a high resolution 490 pixel camera with 4 degree field of view was present on the telescope. Characterization of the off-axis response of this instrument was done using observations of the Crab Nebula. No significant emission was detected from the eight unidentified EGRET sources observed and upper limits are presented as a function of position.
We present a new method of image cleaning for imaging atmospheric Cherenkov telescopes. The method is based on the utilization of wavelets to identify noise pixels in images of gamma-ray and hadronic induced air showers. This method selects more signal pixels with Cherenkov photons than traditional image processing techniques. In addition, the method is equally efficient at rejecting pixels with noise alone. The inclusion of more signal pixels in an image of an air shower allows for a more accurate reconstruction, especially at lower gamma-ray energies that produce low levels of light. We pres…
We present a method of atmospheric Cherenkov imaging which reconstructs the unique arrival direction of TeV gamma rays using a single telescope. The method is derived empirically and utilizes several features of gamma-ray induced air showers which determine, to a precision of 0.12 degrees, the arrival direction of photons, on an event-by-event basis. Data from the Whipple Observatory's 10 m gamma-ray telescope is utilized to test selection methods based on source location. The results compare these selection methods with traditional techniques and three different camera fields of view. The met…
The development of the atmospheric Cherenkov imaging technique has led to significant advances in gamma-ray detection sensitivity in the energy range from 200 GeV to 50 TeV. The Whipple Observatory 10m reflector has detected the first galactic and extragalactic sources in the Northern Hemisphere; the Crab Nebula has been established as the standard candle for ground-based gamma-ray astronomy. The highly variable Active Galactic Nuclei, Markarian 421 and Markarian 501, have proved to be particularly interesting. A new generation of telescopes with improved sensitivity has the promise of interes…
We present the status and motivation of the Short GAmma Ray Front Air Cherenkov Experiment (SGARFACE) which will be operated parallel to standard Very High Energy gamma-ray observations using the Whipple 10m telescope. SGARFACE is sensitive to 100MeV-10GeV gamma-ray bursts with durations ranging from 100ns to 100us providing a fluence sensitivity as low as few $\rm 1E-9 erg/cm^2. Preliminary data taking started in November 2002.
The VERITAS collaboration has observed the high-frequency-peaked BL Lac object 1ES 1218+304 using an array of several imaging Cherenkov telescopes located at the Fred Lawrence Whipple Observatory in Southern Arizona. A gamma-ray signal was detected with high significance for the observations taken during several months in the 2006-2007 observing season. Here we present the detection of 1ES 1218+304 in very-high-energy gamma rays.
We consider neutralino annihilation in dense extragalactic systems known to be dominated by dark matter, in particular M87 and several local dwarf spheroidal galaxies. These annihilations can produce energetic gamma rays which may be visible to atmospheric Cerenkov telescopes. We explore the supersymmetric parameter space, and compute the expected flux of gamma--rays coming from these objects. It is shown that some parts of the parameter space lead to a signal observable with the next generation of Cerenkov telescopes, provided the supersymmetric dark matter has a clumpy structure, as may be e…
We present multiwavelength observations of the BL Lacertae object Markarian 501 (Mrk 501) in 1997 between April 8 and April 19. Evidence of correlated variability is seen in very high energy (VHE, E > 350 GeV) gamma-ray observations taken with the Whipple Observatory gamma-ray telescope, data from the Oriented Scintillation Spectrometer Experiment of the Compton Gamma-Ray Observatory, and quicklook results from the All-Sky Monitor of the Rossi X-ray Timing Explorer while the Energetic Gamma-Ray Experiment Telescope did not detect Mrk 501. Short term optical correlations are not conclusive but …
We present the results of a search for pulsed TeV emission from the Crab pulsar using the Whipple Observatory's 10 m gamma-ray telescope. The direction of the Crab pulsar was observed for a total of 73.4 hours between 1994 November and 1997 March. During this period the Whipple 10 m telescope was operated at its lowest energy threshold to date. Spectral analysis techniques were applied to search for the presence of a gamma-ray signal from the Crab pulsar over the energy band 250 GeV to 4 TeV. We do not see any evidence of the 33 ms pulsations present in other energy bands from the Crab pulsar.…
Recent advances in N-body simulations of cold dark matter halos point to a substantial density enhancement near the center. This means that, e.g., the $γ$ ray signals from neutralino dark matter annihilations would be significantly enhanced compared to old estimates based on an isothermal sphere model with large core radius. Another important development concerns new detectors, both space- and ground-based, which will cover the window between 50 and 300 GeV where presently no cosmic $γ$-ray data are available. Thirdly, new calculations of the $γ$-ray line signal (a sharp spike of $10^{-3}$ rel…
We report on observations of the Perseus cluster of galaxies using the 10 m Whipple $γ$-ray telescope during the 2004-2005 observing season. We apply a two dimensional analysis technique to allow us to scrutinize the cluster for TeV emission. In this contribution we will first calculate flux upper limits on TeV gamma-ray sources within the cluster. Second, we derive an upper limit on the extended cluster emission. We then compare the flux upper limits with the EGRET upper limit at 100 MeV and theoretical models.
We report on a multiwavelength campaign on the TeV gamma-ray blazar Markarian (Mrk) 421 performed during December 2002 and January 2003. These target of opportunity observations were initiated by the detection of X-ray and TeV gamma-ray flares with the All Sky Monitor (ASM) on board the Rossi X-ray Timing Explorer (RXTE) and the 10 m Whipple gamma-ray telescope.The campaign included observational coverage in the radio (University of Michigan Radio Astronomy Observatory), optical (Boltwood, La Palma KVA 0.6m, WIYN 0.9m), X-ray (RXTE pointed telescopes), and TeV gamma-ray (Whipple and HEGRA) ban…
A sample of 54 selected Active Galactic Nuclei (AGN) has been observed with the HEGRA stereoscopic system of Cherenkov Telescopes between 1996 and 2002 in the TeV energy regime. The observations were motivated by the positive results obtained for Mkn 421 and Mkn 501. The distances of the selected objects vary over a large range of redshifts between z = 0.004 and z = 0.7. Among the observed AGN are the meanwhile established TeV-emitting BL Lac type objects H1426+428 and 1ES1959+650. Furthermore the BL Lac object 1ES2344+514 and the radio galaxy M87 show evidence for a signal on a 4 sigma level.…
A very high energy (VHE) gamma-ray signal has been detected at the 5.4 sigma level from H1426+428, an x-ray selected BL Lacertae object at a redshift of 0.129. The object was monitored from 1995 - 1998 with the Whipple 10m imaging atmospheric Cherenkov telescope as part of a general blazar survey; the results of these observations, although not statistically significant, were consistently positive. X-ray observations of H1426+428 during 1999 with the BeppoSAX instrument revealed that the peak of its synchrotron spectrum occurs at > 100 keV, leading to the prediction of observable TeV emission …
Some candidate dark matter particles, such as neutralinos in supersymmetry, would annihilate producing GeV/TeV gamma rays. We report on recent observations of two dwarf spheroid galaxies, Draco, Ursa Minor, the compact elliptical galaxy M32, and the spiral galaxy M33 with the Whipple 10m gamma-ray telescope. No significant signal was found, and we derived upper limits for the gamma-ray flux from each object. We discuss our astrophysical selection criteria for these galaxies in the context of an indirect search for dark matter and the implications of these flux upper limits on the density of ne…
Neutralinos are the natural well-motivated candidates to provide the non-baryonic dark matter of the universe which may produce detectable signals through their annihilation into neutrinos, photons or positrons. Due to its high flux sensitivity and low energy threshold, the MAGIC Cherenkov telescope could potentially detect the neutralino annihilation high energy photon products. In the framework of minimal supergravity, the neutralino SUSY parameter space can be scanned in different benchmark scenarios defined after accelerator and cosmology constraints. Moreover, the neutralino density profi…
We report a possible detection of TeV gamma-rays from the Galactic Center by the Whipple 10m gamma-ray telescope. Twenty-six hours of data were taken over an extended period from 1995 through 2003 resulting in a total significance of 3.7 standard deviations. The measured excess corresponds to an integral flux of \Flux above an energy of $2.8 \mathrm{TeV}$, roughly 40% of the flux from the Crab Nebula at this energy. The 95% confidence region has an angular extent of about 15 arcmin and includes the position of Sgr A*. The detection is consistent with a point source and shows no evidence for va…
We give an overview of the current status and scientific goals of VERITAS, a proposed hexagonal array of seven 10 m aperture imaging Cherenkov telescopes. The selected site is Montosa Canyon (1390 m a.s.l.) at the Whipple Observatory, Arizona. Each telescope, of 12 m focal length, will initially be equipped with a 499 element photomultiplier camera covering a 3.5 degree field of view. A central station will initiate the readout of 500 MHz FADCs upon receipt of multiple telescope triggers. The minimum detectable flux sensitivity will be 0.5% of the Crab Nebula flux at 200 GeV. Detailed simulati…
VERITAS is a proposed major ground-based gamma-ray observatory to be built at the Whipple Observatory in southern Arizona, USA. It will consist of an array of seven 10m imaging Cherenkov telescopes designed to conduct gamma-ray observations in the energy range of 50 GeV - 50 TeV. A description of the baseline VERITAS design and optimization criteria are presented. We provide basic characteristics of the array performance for observations of point sources, such as angular resolution, energy threshold, energy resolution, and integral flux sensitivity. The limiting factors of the VERITAS performa…
Indirect detection of particle dark matter relies upon pair annihilation of Weakly Interaction Massive Particles (WIMPs), which is complementary to the well known techniques of direct detection (WIMP-nucleus scattering) and collider production (WIMP pair production). Pair annihilation of WIMPs results in the production of gamma-rays, neutrinos, and anti-matter. Of the various experiments sensitive to indirect detection of dark matter, the Gamma-ray Large Area Space Telescope (GLAST) may play the most crucial role in the next few years. After launch in late 2007, The GLAST Large Area Telescope …
The Crab Nebula has been observed by the HEGRA (High-Energy Gamma-Ray Astronomy) stereoscopic system of imaging air Cherenkov telescopes (IACTs) for a total of about 200 hrs during two observational campaigns: from September 1997 to March 1998 and from August 1998 to April 1999. The recent detailed studies of system performance give an energy threshold and an energy resolution for gamma-rays of 500 GeV and ~ 18%, respectively. The Crab energy spectrum was measured with the HEGRA IACT system in a very broad energy range up to 20 TeV, using observations at zenith angles up to 65 degrees. The Cra…
We present the result of the observation of the ultrafaint dwarf galaxy Willman 1 performed with the 17 m MAGIC telescope during 15.5 hr between March and May 2008. No significant $γ$-ray emission was found. We derived upper limits of the order of $10^{-12}$ ph cm$^{-2}$ s$^{-1}$ on the integral flux above 100 GeV, which we compare with predictions from several of the established neutralino benchmark models in the mSUGRA parameter space. The neutralino annihilation spectra are defined after including the recently quantified contribution of internal bremsstrahlung from the virtual sparticles th…
We present near-infrared and optical observations of the afterglow to the Gamma-Ray Burst (GRB) 991216 obtained with the F. L. Whipple Observatory 1.2-m telescope and the University of Hawaii 2.2-m telescope. The observations range from 15 hours to 3.8 days after the burst. The temporal behavior of the data is well described by a single power-law decay with index -1.36 +/-0.04, independent of wavelength. The optical spectral energy distribution, corrected for significant Galactic reddening of E(B-V)=0.626, is well fitted by a single power-law with index -0.58 +/- 0.08. Combining the IR/optical…
A new revision of the gamma flux that we expect to detect in Imaging Atmospheric Cherenkov Telescopes (IACTs) from neutralino annihilation in the Draco dSph is presented in the context of the minimal supersymmetric standard models (MSSM) compatible with the present phenomenological and cosmological constraints, and using the dark matter (DM) density profiles compatible with the latest observations. This revision takes also into account the important effect of the Point Spread Function (PSF) of the telescope, and is valid not only for Draco but also for any other DM target. We show that this ef…
A new estimation of the gamma-ray flux that we expect to detect from SUSY dark matter annihilation from the Draco dSph is presented using the DM density profiles compatible with the latest observations. This calculation takes also into account the important effect of the Point Spread Function (PSF) of the telescope. We show that this effect is crucial in the way we will observe and interpret a possible signal detection. Finally, we discuss the prospects to detect a possible gamma signal from Draco for MAGIC and GLAST.
We review recent results on the search for high energy extraterrestrial neutrinos, neutrinos induced by WIMP annihilation and neutrinos coincident with Gamma Ray Bursts as obtained with the Baikal neutrino telescope NT-200. We describe the moderate upgrade of NT-200 towards a ~10 Mton scale detector NT-200+. We finally draw a few lessons from our experience which may be of use for other underwater experiments.
The beaming pattern of thermal annihilation radiation is broader than the beaming pattern produced by isotropic nonthermal electrons and positrons in the jets of radio-emitting active galactic nuclei which Compton scatter photons from an external isotropic radiation field. Thus blueshifted thermal annihilation radiation can provide the dominant contribution to the high-energy radiation spectrum at observing angles theta > 1/Gamma, where Gamma is the bulk Lorentz factor of the outflowing plasma. This effect may account for the spectral features of MeV blazars discovered with the Compton Telesco…
