PoS(ICRC2015)868 http://pos.sissa.it/ † for the VERITAS Collaboration ∗ [email protected] Speaker. veritas.sao.arizona.edu VERITAS is a ground-based array ofof four the world’s 12-meter most telescopes sensitive detectors near of Tucson, veryITAS Arizona high has and energy a (VHE: is wide >100 one GeV) scientific gamma reachwell rays. that VER- as includes the the search study of forrays. extragalactic astrophysical In and this signatures Galactic presentation, of we objects will dark as present summarize some matter the of current and the status the scientific of highlights measurement the since VERITAS of 2013. observatory and cosmic ∗ † Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. c

The 34th International Cosmic Ray Conference, 30 July- 6 August, 2015 The Hague, The Netherlands McGill University E-mail: David Staszak Science Highlights from VERITAS PoS(ICRC2015)868 ], ], 8 3 165 ∼ ]. Each 1 David Staszak 30 TeV. VERITAS has > to map out the scientific pri- at 1 TeV (68% containment), an ◦ 100 m between telescopes[ ∼ Long Term Plan 2 ]. We collect data under bright moonlight conditions using 7 1400 hours of data per season, with two months of monsoons ∼ 50%[ ] and instrumented each of the cameras with new, high efficiency ]. In the current configuration, VERITAS can detect a 1% Crab 4 6 > 25%, and a pointing accuracy of less than 50 arcsec. − 25 hours and has an angular resolution of 0.1 ∼ field of view on the sky. Since inauguration, the array has undergone two major ◦ ]. The new PMTs collect significantly more light and have impacted the VERITAS science ]. This upgrade, when combined with a newly developed mirror alignment technique[ 5 shows the array in its current configuration and summarizes the overall sensitivity of these 2 VERITAS is now a mature scientific instrument that has completed 8 years of successful data VERITAS typically collects The Very Energetic Radiation Imaging Telescope Array System (VERITAS) is a ground-based The VERITAS array was completed in 2007 and consists of four imaging atmospheric 1 collection with minimal hardware problems.from at The least VERITAS eight sourcesource different catalog source now discovery classes. lists to 54 collecting The objects bounty. scientific deep focus Last exposures of year on VERITAS the known has collaboration evolved objects developed from that a yield the most scientific two non-standard techniques, one withfilters reduced high placed voltage over PMT settings theconditions and PMTs. was the demonstrated other by with the The detection UV of utilityunder a bright of moonlight flare conditions. state aggressively in This a represents adding the BLdata first Lac observation by such object, VERITAS. publication time 1ES using 1727+502[ bright under moonlight these orities for the nextfor five our years. core The science planwithin plan, each reserves which of 70% includes the of a main our mix VERITAS science average of programs. yearly sources The observational that remaining time offer time the is most opened up scientific at impact an an- improved the angular resolution ofCrab the Nebula source instrument down and from brought 50replaced the hours the of sensitivity L2 observation for trigger to detecting 30 system[ hours. aPMTs[ 1% The second, over 2011-2012, programs where low energy sensitivity issoft critical. spectrum In AGN particular, that we would have noture now have detected been several possible new under thethree original hardware array configuration. configurations[ Fig- Nebula source in energy resolution of 15 in July and Augustcharacterized where by observation the moon is in impossible. the sky but Of with this moon illumination total, less than low 30%, moonlight accounts observations, for array located at theworld’s Fred most Lawrence sensitive Whipple gamma-ray instruments Observatory at in energies southern of Arizona 85 and GeV is to one of the Cherenkov telescopes (IACTs) with typical baselines of VERITAS Science Highlights 1. Introduction a wide scientific reach thatsearch includes for the astrophysical study signatures of of dark extragalacticwill matter and present and some Galactic the of objects measurement the of as recent cosmic scientificresults well highlights rays. shown as from at This the VERITAS, the paper focusing 2015 in ICRC particular on in those The Hague, Netherlands. telescope comprises a 12 m reflectorcreating and a an 3.5 imaging camera thathardware is upgrades. instrumented with The 499 first, PMTs, array[ in 2009, relocated one of the telescopes to better symmetrize the hours. Additionally, VERITAS has actively pursued observationswhere into the bright moon moonlight is conditions, illuminated PoS(ICRC2015)868 . 1 65% of all David Staszak ∼ -VERITAS-GI program Fermi 3 40% of VERITAS observational time and ∼ At the top the VERITAS array is shown in its present configuration. Shown in the bottom left http://fermi.gsfc.nasa.gov/ssc/proposals/veritas.html Extragalactic sources account for 1 Figure 1: panel is the VERITAS differentialprior sensitivity to using T1 similar cuts move, inbottom V5 all right - three panel after hardware are T1 configurations:bright VERITAS move moonlight effective V4 but observing areas - before configurations. for PMT these upgrade, hardware V6 configurations - as after well PMT as upgrade. fornual the Shown time-allocation two in competition. the Additionally, up tois 15% accessible, with of funding, the to total external VERITAS observation scientists time through the 2. Extragalactic Science VERITAS detections. All of these detections aregalaxy BL Lac M82 objects and with the three two exceptions, radio the galaxies100 starburst M87 northern and blazars NGC and 1275. pursues an VERITAS now activeknown multi-wavelength has and monitoring exposures candidate program on to objects. over detect BL flaresto in Lacs hours are to known years, to and exhibit catching fluxwhere an variation otherwise object on its in the a quiescent scale high state of state may minutes may be be too a dim. means to Further, discover besides VHE a emission means of discovering new VERITAS Science Highlights PoS(ICRC2015)868 -LAT ], here 9 15 hours ]. Unlike ∼ 15 Fermi David Staszak 3), but VERITAS has been . 0 ] and this source was targeted , effectively creating a gamma- 0.41), PKS 1222+16 (z=0.432), < − 20 < z e z ][ + < 19 + e → in 6 hours of VERITAS exposure[ 0.60), as well as two new source detections, ]. VERITAS has an active program to monitor -LAT as a good candidate for VHE observation VHE > σ γ 18 4 10 + ∼ Fermi EBL γ ]. The redshift of this object is unknown (photometrically 17 ][ 16 [ σ ]. The redshift for this object is particularly distant, z=0.939, mak- 14 0.58), PKS 1424+240 (z < z < 39) but it was identified by . 3). VERITAS observations were triggered by an email alert from the . 0 -LAT team[ 3 > ∼ -LAT data of known and potential VHE emitters[ Fermi FHL 1 Γ The scientific focus of blazar observations at VERITAS has historically been a mix of source One of the biggest blazar science stories over the last couple of years has been the detection Multi-wavelength (MWL) data is critical to blazar science during both flaring and quiescent The last six months have been particularly active for northern gamma-ray blazars, result- Fermi 5% Crab Nebula flux above 80 GeV. VERITAS observations were triggered by a detection the discovery and deep exposures onprogram, known VERITAS now objects. focuses the majority To of maximize itsgroup observational the time of scientific on sources. deep output This exposures of of program a is the select discussed blazar in more detail elsewhere in these proceedings[ of VHE gamma-ray sources thatthis are story. more and Most more blazars distant. are VERITAS relatively has close been (with at redshifts the of center of in their hard source catalog, 1FHLthe J2244.0+2020[ other recent flare detections, this source isdate rather ( soft and was not assumed toteam. be a good VHE candi- we will focus on a few recent highlights and ongoing studies. collecting a sizable list of more distant objects: 3C 66A (0.33 ing preliminary Extragalactic Background Light (EBL)J2243+203 constraints was for observed this flare for competitive. 280 RGB cumulative minutes significance between of Dec. 5.6 21stestimated and at Dec. z 24th, 2014, resulting in a for observations after it(z=0.135) exhibited is a an LBL/IBL flux that increase was detected in at the 1-100 GeV band. Finally, S3 1227+25 PG 1553+113 (0.43 S3 0218+357 (z=0.944), and PKSing 1441+25 because (0.939). VHE gamma Distant rays blazarsbackground are light are expected (EBL) cosmologically to via interest- interact pair with creation, intervening low-energy extragalactic states, and VERITAS has many ongoingof MWL the programs spectral energy and distribution partnerships. (SED)tions Broadband provides within a modelling the means source to jets, study the andensure relativistic to all particle distinguish VERITAS popula- between blazar different detections gamma-ray haveto emission MWL be models. data. compatible We with To the date, synchrotron mostfavor self-compton other VERITAS (SSC) SEDs mechanisms. emission are models, found though a few slightly ing in several new VERITASJ2243+203, detections and S3 of 1227+25. potentially PKS interestingtected 1441+25 by objects: is VERITAS and the PKS the second 1441+25, fifth flat RGB at spectrum VHE radio energies. quasar (FSRQ) VERITAS observed de- this object for VERITAS Science Highlights sources, flares provide a way toperiod accumulate of large time. gamma-ray statistics on Thiscosmological a can quantities given be can object be in used probed. a to short push spectral measurements to higher energies where many over the course of a∼ week starting the nightprevious of April night 15th, from 2015, MAGIC, andfrom which found the were it themselves to exhibit triggered a by steady monitoring and alert emails ray "horizon". The probability of this interaction is characterized by an exponential attenuation PoS(ICRC2015)868 -LAT and ]. Unfortu- David Staszak 100 GeV are 13 ∼ Fermi -LAT data are additionally shown, where both ), we did not extend the energy for which σ Fermi 5 750 GeV energy range. Measured and deabsorbed using the EBL model from Gilmore[ vs. 8.5 − 2 1 σ ∼ data is also presented. Insets show the deabsorbed spectral points Fermi ]. The early 2009 VERITAS dataset was complemented by a deep 2013 3 in exposure(14.4 . 12 2 is the optical depth and depends on the object’s redshift and the gamma-ray 6[ τ ∼ . 0 > z , where Broadband PKS 1424+240 SEDs for VERITAS data collected in 2009 and 2013, corresponding τ − e PKS 1424+240 is a HBL discovered by VERITAS in 2009 that was recently found to be very VERITAS blazar measurements can also be used to indirectly probe the magnetic fields that spectra for these datasets are shown in Fig. distant, with energy. Of particular utilitynot in expected to these be studies significantlyVERITAS is energies absorbed, can the be so fact used a to that extract comparisonspectra, gamma information respectively. of about rays energy the below intrinsic spectra and at absorbed gamma-ray factor, dataset and both were analyzed over the contemporaneous and the full set of for both datasets. there was a spectral measurement. Inenergies both is datasets seen a after marginal correcting hardening foridence in EBL of the an absorption. spectrum overestimation at A of higher high theinternal energy EBL photon-photon spectral density hardening absorption or can or some be more gamma-raycosmic-ray ev- exotic production line-of-sight physical interactions. from mechanism, secondary such as cascades caused by Figure 2: to relatively high and low states, respectively. Swift and nately, the flux in 2013with was the less factor than of in 2009, so while the detection of the source is improved VERITAS Science Highlights PoS(ICRC2015)868 16 15 − − 10 × ) , where the , and 10 10 16 David Staszak 15 − − − ], Mrk 501, VER 5 ( 10 21 , 10 < 14 . − σ = 10 data) / − IGMF shows this comparison for three 3 ]. The best sources for this type of 21 ]. The field strengths selected represent 22 6 for energies between 160 GeV and 1 TeV. 1 − s 1 − ) for three of the VERITAS blazars considered in [ 2 TeV θ 2 − cm 200. Shown in the top panels are the data in blue and simulated point sources 12 + − 10 × 2.69 − The angular distribution ( 211, and 1ES 0229 + The VERITAS observations of seven VHE gamma-ray blazars have allowed for a sensitive Two starburst galaxies (SBGs), galaxies that are characterized by exceptionally high star for- using a three dimensional semi-analytical cascade code[ of the seven blazarsdependent considered limits here. are presented for No assumed significant IGMF strengths evidence of of B broadening is found. Model investigation are hard-spectrum, relatively distantat point-source VHE blazars energies. that The are spatialthe strongly extent simulated detected of VERITAS the point-spread data function for (PSF). each Figure of these seven objects is compared with a range that VERITAS could potentially beexpected sensitive to, angular bounded broadening by would the limit be of object, too upper small limits to are detect. placed on Foremission the (as each fraction opposed field to of strength direct the and emission). total VERITAS Based measured on emission these arising ULs, from IGMF cascade strengths of Figure 3: search for an angular broadening signature of the IGMF[ VERITAS Science Highlights J0521 fill the voids between the large-scalethe structures of intergalactic the magnetic universe. field These (IGMF), fields,leaving are known their collectively believed as magnitude to and exist origin butrays as are a of difficult to critical order measure unresolved of directly, problem.positron hundreds pair As whose of described trajectory above, GeV is gamma sensitive aremicrowave to the expected background IGMF. to These (CMB) electrons interact photons canrays. then with to up-scatter Cascade the create cosmic gamma rays EBL, a would creating secondary exhibitof temporal an the cascade and IGMF, electron- spatial of such properties as lower imprinted a byinstrument energy time-delay the PSF. and gamma strength an angular broadening of the gamma-ray signal beyond the G are excluded at 95%that are confidence strong level. enough to Note isotropizefields that the considered a electron/positron here. non-detection pair at here Model-independent thecalculated does source limits assuming not and a on rule spectral only the index applies out matching flux to fields limits the the from intrinsic of spectral 0.17 extended index, emission resulting 99% were CL also upper (MC) in red. Shown in the bottom panels are the residuals defined as (MC PoS(ICRC2015)868 David Staszak -LAT and VERITAS data in filled red Fermi 7 ]. Further, we show contemporaneous VERITAS data taken 25 -LAT data and upper limits of the extended object with VERITAS ], we show a detailed analysis of the detection and morphology of M Fermi 24 Spectral energy distribution of the Tycho SNR with 0014. Our result on Arp 220 represents the most sensitive upper limits on a ULIRG at VHE − VERITAS has a rich and varied Galactic program with 20 source detections, including super- At this conference we present several new Crab Nebula and pulsar results. This includes the ], we show upper limits on VHE gamma-ray emission from two ULIRGs, Arp 220 and IRAS 23 31 at lower energies with mation rates (SFRs), have beenThese detected objects provide by strong VHE evidence gamma-rayand of instruments, represent the the M correlation only 82 between known andativistic high extragalactic NGC point-sources SFRs jet. detected 253. and at Ultra-luminous VHE VHE emission, infraredcosmic-ray energies galaxies without acceleration a (ULIRGs) and rel- are emission objectstain mechanisms. predicted large to They amounts exhibit are of[ similar objects dust, with which high absorbs SFRs17208 the that object’s con- UV light, re-radiating it in the FIR. In nova remnants (SNR), pulsar wind nebulae (PWN), high-masssources, x-ray and binaries one (HMXB), unidentified pulsar. From itsregions position of in intense the star northern formation hemisphere, like VERITASsar, is the the able Cygnus Galactic to arm, observe Center iconic region objects (above likeGalactic 2 the objects TeV), Crab as visible Nebula well to and VERITAS as pul- are most the of most the thoroughly historical studied SNRs. objects Many acrossfirst of the the VERITAS spectrum. measurement on thefinding extension no evidence of for the extension[ VHE emission region of the Crab Nebula, squares and circles, respectively. Acomparison. representative sample of gamma-ray emission models is presented for energies to date and begins toSFR constrain and theoretical VHE models. emission We with further a test deepgalaxy the exposure to correlation on between the the nearby Milky galaxy Way M andtest 31. contains this M a correlation. 31 dense, is the star-forming In closest ring [ spiral which is of particulardata. interest to 3. Galactic Science Figure 4: VERITAS Science Highlights PoS(ICRC2015)868 . With syst 30 . David Staszak 0 ± stat 51 . ]. 72 hours of VERITAS 0 32 ∼ ± 95 . 1 = 2 times more VERITAS data than Γ ∼ -LAT energies and demonstrate no ], and IC 443[ 31 Fermi as opposed to 8 ], Cas A[ stat 30 -LAT data are compared with a selection of favored 42 . 0 ± Fermi 92 . 2 = ]. The Crab pulsar, the power source driving the Nebula energetics, Γ 26 -LAT measurement of W 44 and IC 443 at low energies found the Fermi light curve for three orbits of data taken in the 2014 season. October is shown as ◦ ] in data already on disk. 61 + ]. While hadronic acceleration is favored at VHE energies as well, these energies 28 presents new results for the Tycho SNR, including 29 4 LS I ] and discuss the status of an archival search of VERITAS data for signals from known pulsars[ 27 Figure Historically, the primary motivation for gamma-ray astronomy was to detect and understand previously published. VERITAS and gamma-ray emission models for Tycho (mostgrade are of VERITAS hadronic-emission led dominated). to a The lowerTycho camera energy spectrum threshold over up- of a the wider range instrument of andthan energies. allowed the us The previously to measurement published, measure of the the updated spectrum is softer data[ the sites of cosmic-ray acceleration.a The plausible diffusive and shocks generally ofevidence supernovae accepted remnants of explanation. (SNR) the remain While accelerationless X-ray of clear. observations electrons have to presented A VHEexpected clear recent signature energies, of the hadronic hadronic emission,interactions[ acceleration evidence picture of is the neutralare pion-decay less explored. from To proton-proton study thisSNRs. VERITAS has In committed these significant proceedings, observational VERITAS timeexposures, has including on a presentations known number on of Tycho[ exciting new SNR results based on deep Fermi was the first pulsar detectedthe above 100 Crab GeV. pulsar In with these twice proceedingsalso the we show present data an an used upper updated in study limit the of on initial VERITAS pulsations discovery from paper the from Geminga 2011. pulsar We from this new result and softer spectrumshown. above 500 GeV, data are in tension with the emission scenarios Figure 5: during the recent dramatic flux variability observed at VERITAS Science Highlights orange circles, November as purplenight diamonds, with and 99% December confidence as level blue flux squares. upper limits Each shown bin as represents arrows. a single variability at VHE energies[ PoS(ICRC2015)868 5 -LAT and ]. Figure David Staszak 34 Fermi elevation for VER- ◦ , roughly 30% of the Crab , the central supermassive 303 to date[ 1 ∗ ◦ − s 2 − cm 12 − 10 26.5 elliptical orbit. This system has been ∼ × ) stat 9 3.4 ± 30 TeV, but this measurement helps to improve our un- − 20 TeV, potentially constraining leptonic emission models 3 more than the published data set. This data also includes ∼ ∼ ]. The spectrum of both objects are measured with better statis- 303 is a system that contains a compact object (black hole or ◦ 35 , both a broken power-law and power-law with an exponential cutoff ∗ 303, HESS J0632+057, and LS 5039. VERITAS commits time to both con- ◦ ]. The spectrum exhibited a cutoff at GeV energies near values typical of the 33 pulsar population and was suggestive of separate emission populations at GeV and TeV en- Despite the fact that the Galactic center (GC) region never rises above 30 Detecting and understanding the VHE gamma-ray emission from high mass x-ray binary VERITAS has additionally taken a large exposures on the Cas A and IC 443 SNRs with our 10% Crab Nebula flux level, though there have been years where this source wasn’t detected at VERITAS data[ studied extensively across thesince spectrum 2006 and (totalling VERITAS over has 180∼ now hours). collected data VERITAS typically on detectsall. it emission Conversely, MeV/GeV every near emission year is apastron typically atpublished detected the an throughout energy the spectrum orbit. for VERITAS this recently system using contemporaneous 2011-2012 tics at higher energies thanthe prior G0 measurements. 9+0.1 spectrum A to single energiesfor power-law of this fit is object. found For to Sgr well describe A can explain the data over the range of 2 neutron star) orbiting a large main sequence star in a Fermi ergies. We can reportshows here data the from brightest October VHE tothe detection December source of was in detected LS 2014 with I sampling a flux +63 three of separate (31.9 orbits. On October 18th tinued observations on previously detected objectsweather as observations. well as LS to I search for +63 new objects using poor Nebula flux. The flare rise and fallorbits times were are detected found closer to be to veryVery the fast quick, usual changes less than in flux a the level day, flux indicating and pointtesting subsequent some to existing level rapid models of changes of in orbit-to-orbit the the emission. variation. conditions Forrapidly. for example, acceleration wind-wind in collision the zones system, must change quite ITAS, we make an exception toan observe effective area it. boost In above fact, 2measurements TeV as compared of described to the above, standard LZA two observations. observations knownblack We give point present hole us high object, sources statistics and in G0 the 9+0.1[ GC field, Sgr A (HMXB) systems is another important elementare of complex the binary VERITAS systems Galactic where scienceliding VHE program. emission winds. These can be There powered areVERITAS: by LS currently accretion I or five +63 arise such from systems col- detected at TeV energies, three of them by a fraction of the observationsshowers taken to at traverse large a zenith largerfactor angles of atmospheric 5 (LZAs). slant at high depth, LZA energies (above observations providing 1-2spectrum TeV). require an has No extension air been increased is extended seen detection for on area thewe both remnant by and ends, also the a now VERITAS present covering data 400on from GeV to 155 the 7 hours few-arcmin TeV. In on scale theseincluding IC proceedings and possible 443. sources we of emission VERITAS will from can thestructures. show shell now of results resolve the remnant on emission and from structure the other nearby emission gaseous morphology of this object, upgraded cameras. In these proceedings,Cas we A, present which data from represents nearly a 60 factor hours of of observations on VERITAS Science Highlights PoS(ICRC2015)868 David Staszak , and G0 9+0.1, as well ∗ in these maps and is likely σ -LAT 3FGL sources. 2 TeV, as well as evidence for the exis- Fermi Significance maps of the Galactic Center re- > 2 TeV. Shown in the top panel are the locations of the 10 Figure 6: gion using VERITAS data with∼ an energy threshold of subtracted point sources, Sgr A as the VERITAS source, VER J1746-289.middle Shown panel in the is theVLA significance 20cm map radio contours. withis overlays Shown the in of significance the map bottom with overlays panel events of and H.E.S.S. excess 100 GeV ∼ with several local statistically significant enhancements, including ∗ , and for masses above The VERITAS DM program focuses The existence of Dark Matter (DM) wimp . It extends west of Sgr A its search forof DM object classes, signalsvantages each in with and a its disadvantages. variety gets own ad- include the Thehalo GC, candidates, galaxy tar- Galactic clusters, and DM dwarf spheroidal sub- (dSph) galaxies. For thesurements presented purposes at of this this conference. proceedings, we will focus on the new mea- IACT arrays like VERITAS are sensitive to these signals. IACT experiments probe re- gions of theoretical phase spaceble inaccessi- to nuclear recoil andexperiments. accelerator-based Additionally, any new parti- cle discovered in a direct detectionment experi- or at the LHC willconfirmed need as to the be astrophysical further DM, anvantage ad- observatories like VERITAS bring to the table. has been confirmed byat observational data various wavelengths andtrophysical at various scales. as- candidates Among for a the particleDM, leading interpretation Weakly Interacting of Massive Particles (WIMPs) present ageneric extension well-motivated to and theof Standard particle physics. Model WIMPsto are produce predicted photon finaldirect states annihilation from and/or both decayas channels well as through hadronic orcay leptonic chains de- (photons arise via finaldiation state in ra- leptonic chains).gamma-ray The predicted distribution dependsM on the correlated with known non-thermal structures in the region. 4. Dark Matter Science VER J1746-289. VER J1746-289 is detected at a significance of 7.8 6 VERITAS Science Highlights derstanding of the cutoff energy.a residual After sky removing map both shows of a these rich point field sources of ridge from emission the GC field, tence of a new extended source, VER J1746-289. This ridge emission structure is shown in Fig. PoS(ICRC2015)868 7 ]. However, David Staszak 37 (right), and prior ][ ττ 36 ]. It is based on an event weighting method 38 11 ]. These results are an extension of the techniques 40 systematical uncertainty on the DM density profile is represented -LAT data[ shows results from a joint likelihood method using data from σ 7 Fermi ) times more DM mass than visible matter, and have no predicted astrophys- 3 -LAT unassociated objects to follow-up with VHE energies. Candidates were 10 ( O 230 total hours of observation[ Fermi ∼ Expected annihilation cross section limits for the joint analysis of dwarf data as a function of DM VERITAS currently devotes 150 hours of observation time per year to dSph galaxies. DSph High resolution simulations of a DM halo similar to the Milky Way have found DM substruc- ical gamma-ray signals. VERITAS hasdSph sources, previously the published most limits constraining arising on fromDM observations a physics of 48 is hour individual the exposure same on across Segueall different I[ dSphs, dSph so objects this cohesively. Figure topic benefits from an analysis that includes galaxies are objects of intense studyinated because - they are hosting relatively nearby (20-200 kpc), are DM dom- tures clumped at all scales.baryonic matter Not to all be of visible,VERITAS these has and subhalos enacted some are a in program predicted to factdidates to select may from have a accumulated be small enough detectable sample of at the gamma-ray best energies motivated alone. DM subhalo can- as a blue band and the natural cross section is shown as a grey band for comparison. originally developed for use on that assigns each event aenergy weight of the based event, and on the three reconstructedstatistic position factors: is of the the then event dSph defined relative to as field theground the the dSph. plus sum event An DM of optimal came hypothesis test all from, against these thepresents the event null the weights. (background exclusion only) This limits for from statistic thefirst this is full joint analysis used dSph analysis for to dataset. two using test Figure annihilation a allover channels. back- VERITAS previous dSph measurements This significantly. data represents In at this the work, oncefor we and direct also annihilation improves present gamma-ray VERITAS our ULs lines dSph on in a DM the search constraints dSph data. selected based on multi-wavelength properties, lack of time variability, and detectability with VER- Segue 1 results are also displayed. The 1 five dSph fields observed bycomprising VERITAS (Segue 1, Draco, Ursa Minor, Bootes, and Willman 1), Figure 7: particle mass. Limits shown are for 95% confidence level for two channels, bb (left) and VERITAS Science Highlights PoS(ICRC2015)868 a ± 71 100 100 ∼ ∼ > 3.2 − , we show 8 David Staszak 40 GeV. Of the many ] as compared with prior ± 42 ] in these proceedings. This 47 3 hours of their detection. GRB ]. The result qualitatively agrees ∼ 45 TeV. -LAT spectrum into VHE predicts ∼ -LAT detected gamma rays from the burst -LAT data. Fermi Fermi 12 Fermi ] and the progress towards a new measurement of the 0701. We also discuss possible DM model scenarios 43 − ]. 44 ) below (above) a measured cutoff energy of 710 stat 0.1 ± ] we present VERITAS upper limits from the observations of two of these objects, 70 ks after the initial detection. VERITAS began observations of this burst 41 ∼ 4.0 ]. We also discuss the status of a VERITAS program to measure the separated electron ]. It is unfortunate that the initial night of the burst was during the full moon and VERITAS − ( 42 46 We also present a new approach to the analysis of GRB data[ To isolate CRE events in our data and form an energy spectrum, we first use a boosted decision In the VERITAS observational program, gamma-ray bursts (GRBs) are given the highest pri- While VERITAS is primarily a gamma-ray instrument, VERITAS data can also be used to stat /s during the prompt phase of the GRB. Due to the close proximity of this burst and the favorable measurements that pioneered this technique using IACT data[ was not observing, because an extrapolationγ of the zenith observational conditions, VERITAS observations 20 hourseral after emission the models. burst Both still synchrotron constrain and sev- late-time, inverse high-energy Compton emission scenarios detected that by attempt the to LAT explain are the constrained by the VERITASapproach ULs. improves upon the standard Li and Ma approach by statistically accounting for the tree discriminator to quantify events asof more the signal-like data or background-like. is The then electron extracted fraction using an extended likelihood fitting technique. In Fig. with prior satellite-based and ground-basedical measurements uncertainties. of the The CRE best spectrum0.1 fit within for systemat- the datasatellite-based is a and broken ground-based power-law experiments withthe studying spectral second CREs, index direct this measurement of a measurement cutoff represents at an only energy of a and positron fluxes (as wellshadow on as the the isotropic proton cosmic-ray and flux[ anti-proton fluxes) using the imprint of the moon CRI spectrum above 10 TeV[ ority among all sources if they are visible by the array within VERITAS Science Highlights ITAS. In [ 2FGL J0545.6+6018 and 2FGLutilizing J1115.0 the VERITAS dataset and 7 years of the preliminary VERITAS CRE energy spectrum with VERITAS data[ 6. Gamma-ray Bursts 130427A was an unusually bright and nearbyand (z=0.34) ground-based gamma-ray burst observatories. detected In by particular, many the satellite- make several high-impact cosmic-ray measurements. VERITAS benefitsray from electron the fact (CRE) that and cosmic- cosmic-rayand iron are (CRI) therefore events buried are within diffuseof and the these isotropic background signals, signals of the on all standardsame the observed field analysis sky of fields. methods view that do Due not usedata to work. defined [ the In ON these diffuse and proceedings, nature we OFF present regions a within CRE the spectrum with VERITAS 5. Cosmic-ray Measurements for up to ks (about 20 hours)GeV[ after the initial detection but did not detect any significant emission PoS(ICRC2015)868 300 ∼ David Staszak ]. 49 VERITAS AMS Fermi•LAT HESS LE HESS HE ATIC MAGIC Energy [GeV] 290 hours of VERITAS data covering the ∼ 33 13 1010 VERITAS • ICRC 2015 22

1010

dN/dE [m dN/dE E GeV sr s

] -induced muon track events (events that have the best angular uncertainties,

•1 •1 •1 •2 3 µ ν Preliminary cosmic-ray electron spectrum from 4 TeV energy range. Also shown are other satellite-based and ground-based measurements with ]. However, IceCube events to date appear isotropic and no neutrino point-sources have ∼ knowledge of the time dependence of the source light curve. Based on a Monte Carlo study, 48 ). The list of observed positions includes 3 published events and 20 unpublished events that VERITAS has recently completed its eighth successful year of operations, and the scientific The IceCube discovery of an astrophysical flux of high energy neutrinos provides evidence of ◦ 1 priori output of VERITAS since the last ICRCfactors, conference including remains the strong. dedicated This operations is work madeVERITAS of possible observing the by program local many from FLWO source staff, discovery a toobjects, shift deep in exposures as on the well scientifically focus interesting as of the the cultivation of several strong MWL partnerships. Many of the outstanding 8. Conclusion and Outlook ∼ have been shared with VERITAS through a cooperationshow agreement. no Observations statistically of significant these gamma-ray positions signalsfew and percent we of calculate the upper Crab Nebula limits flux in above the 100 range GeV of for a each position[ been discovered. For theevents, past focusing two on years VERITAS has been observing the positions of IceCube the interaction of energetic hadrons and pointsrays[ to the sites of the acceleration of high energy cosmic GeV to overlapping energy data points. The besttion fit and to is the shown as VERITAS data an comes overlaid from dashed a line. broken The power-law gray distribu- band represents the systematical uncertainty. we determined that this method improvesreanalyze our a sensitivity sub-sample to of GRB-like VERITAS signals GRBs. and has been used to 7. IceCube Events Figure 8: VERITAS Science Highlights PoS(ICRC2015)868 David Staszak ], and HFit, a 2D 44 Astropart. Phys, 32, 2009 Fermi ][ 51 and to continue to operate until the data is shown in many of the results -LAT to increase communication and Fermi Swi ft NuSTAR ], a template method[ 42 ][ Astropart.Phys. 25, 391-401, 2006. 14 21 ][ 6 ]. These first results represent an avenue that VERITAS will 2013 ICRC proceedings, arXiv:1307.8360. 40 ]. Additionally, simultaneous A new mirror alignment system for the VERITAS telescopes. 50 VERITAS Telescope 1 Relocation: Details and Improvements. , since they are sensitive to the same non-thermal, relativistic populations of The First VERITAS Telescope. The VERITAS Upgraded Telescope-Level Trigger Systems: Technical Details and NuSTAR and Performance Characterization. proceedings, arXiv:0912.3841. 325, 2010. In addition to upgrading hardware, VERITAS is implementing new analysis techniques to Finally, the results presented here are only a subsample of the science coming from VERITAS This research is supported by grants from the U.S. Department of Energy Office of Science, The VERITAS Collaboration is grateful to Trevor Weekes for his seminal contributions and [3] McCann, A., et al. [4] Zitzer, B., et al. [2] Perkins, J., et al. [1] Holder, J., et al. improve the sensitivity ofadvanced our analysis instrument. methods as a Inboosted replacement decision these of tree the proceedings multivariate standard analyses[ we Hillas show box cuts, several including results the using use of for the last two years.utilize VERITAS overlap plans with to new operate instruments at like least HAWC and until 2019, giving us the opportunity to the U.S. National Science Foundation andWe the acknowledge Smithsonian the Institution, excellent and work byObservatory of and NSERC the at in the technical Canada. collaborating institutions support in staff the construction at and the operation of Fred the Lawrence instrument. Whipple leadership in the field of VHE gamma-ray astrophysics, which made this study possible. References since there is typically excellent coordinationare between the particularly two well instruments. matched HAWC for andsky VERITAS collaboration at since the they same time. view The essentiallyings HAWC the have experiment been same recently set completed region up their of between full the collaboration HAWC, array, VERITAS, between and and annual the meet- experiments. gaussian image fitting technique[ continue to improve, building techniques that will become standard in VERITAS analyses. next generation of ground-based arrays come online. 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