Brian Humensky for the VERITAS Collaboration December 10 ...gibbs/VERITAS_OpsReview...Young, nonthermal X-ray SNR VHE spectrum is a power law to 5 TeV Study of gamma-ray binaries:

FLWO, December 10, 2009 Galactic Science with VERITAS B. Humensky, U. of Chicago

Brian Humensky

for the VERITAS Collaboration

December 10, 2009University of Chicago


27 Source Detections in 6 source classes, at least 10 in the Galactic Plane

http://tevcat.uchicago.edu

1ES 0502+675

1ES 0229+200


Survey of the Cygnus region in TeV: At < 3% Crab flux Discovery of new source VER

J2019+407 Detection of TeV J2032+4130

Discovery of IC 443 in TeV: Classic SNR / MC interaction system Wonderful laboratory to explore

cosmic-ray interaction / diffusion

Discovery of SNR G106.3+2.7 in TeV: Extended TeV source –associated with PWN or SNR/MC interaction?

Discovery of SNR G54.1+0.3 in TeV: Young Crab-like PWN

Detailed study of Cassiopeia A: Young, nonthermal X-ray SNR VHE spectrum is a power law to 5

TeV

Study of gamma-ray binaries: LSI: clear detection only at

apastron. Investigation of GeV/TeV differences.

HESS J0632+057: VERITAS established variability. A new TeV binary system?

Cyg X-3: Convincing -ray detections from AGILE, Fermi → VERITAS follow-up in spring 2010

Detailed study of Crab Nebula: 5detection ~ 70 seconds Search for correlation with giant

radio pulses (with Green Bank) Stability of TeV flux (with MAGIC)

Unidentifieds HESS J1857+026 and HESS

J1858+020 in the W44 region MGRO J1908+063 AGILE transient J2021+4024

Northern PWN Survey Limits 3C 58, Geminga, others


VER J2019+407

Eff

ective e

xposure

tim

e [m

in]

0.8˚

1.0˚1.75˚

Preliminary Flux Limits above 200 GeV (99% CL, all points in survey below 3σ)

<3.0% Crab (point source)

<8.5% Crab (0.2˚ radius extended source)

Possible indication that population in Cygnus region differs from inner galaxy

HESS survey: of 14 sources in -30˚<l< 30˚, saw 12 sources with fluxes ≥ 5% Crab above 200 GeV → expect ~2-3 in VERITAS survey – see zero

Un-biased indication of source population

112 hrs base survey, 56 hrs follow-up to date

VER J2019+407: New VERITAS source

TeV J2032+4130: known source, first detected by HEGRA

Likely associated: MGRO J2031+41, 0FGL J2032.2+4122 (LAT pulsar)

Detection: >5σ at nominal position (no trials)


In northwest region of Cygni SNR (G78.2+2.1) → What exactly is it?

PWN?

core ~0.5˚ away from Fermi pulsar

Association seems unlikely

VERITAS emission does overlap well with radio contours in northwest

Shock-cloud interaction?

Plenty of CO in southeast, little in northwest

Two partial shells in HI, one in northwest (Ladouceur and Pineault 2008, A&A 490, 197)

Cloudlets? Enough mass in HI?

Speculation:

SNR expanded in progenitor’s wind-blown bubble → now encountering surrounding swept-up shell

VERITAS excess map

1420 MHz CGPS Radio contours

No visible -ray emission to the southeast

LAT PSR

J2021+4026

VERITAS

1σ ellipse

PRELIMINARY


SNR / MC Interaction + PWN

Discovered in GeV by EGRET

Now AGILE, Fermi

Discovered in TeV in 2007 by VERITAS & MAGIC

VERITAS: 8.3 , extended emission

TeV emission may be

CR-induced pion production in cloud

associated with the pulsar wind nebula to the south

GeV and TeV emission spatially separated? (both extended)

Broad-band morphological evolution distinguishes between scenarios (not all PWN)

Window into propagation / diffusion of Cosmic Rays in interstellar medium

Abdo et al. submitted

Red: Optical (DSS)Green: CO (Lee et al. 2010, in prep.)Yellow: VERITAS significance (4, 6 )

Troja et al. 2006


VERITAS observations resolve TeV emission overlapping the radio shell of G106.3+2.7

7.3 σ detection in 33 hours (6.0 σ post-trials)

TeV emission is extended

Spans a 0.4 0.6 region

Peak is 0.4 (~6 pc) from PSR

Overlaps region of high CO density

Energy Spectrum – power law

Index: 2.3 ± 0.3stat ± 0.3sys

Flux (> 1 TeV) ~ 5% Crab

Extrapolation of spectrum is consistent within errors with Milagro point at 35 TeV

Excess Map Purple - 12CO Emission (FCRAO)Yellow star – 1AGL J2231+6109

Black – Radio (DRAO)Circle – FGST Error Box

Dot – Pulsar Position

Acciari et al. 2009, ApJ 703 L6


Power-law spectrum: Index: 2.40 ± 0.24stat ± 0.3sys

Flux (> 1 TeV) ~ 2.5% Crab

L / E-dot ~ 0.15% Similar to other young TeV PWNe,

eg G0.9+0.1, Kes 75

VHE -rays from freshly injected electrons

“Cousin of the Crab”

X-ray jet/torus, no thermal shell

Age ~ 2900 years

E-dot = 1.2 × 1037 erg/s

Distance ~ 6.2 kpc

Location compatible with pulsar

Consistent with point source

Lu et al. 2002 (Chandra/ACIS)

Acciari et al. (2009), in prep.


Solid: VERITAS

Dashed: HEGRA

Dotted: MAGIC

Index: 2.61 ± 0.24stat ± 0.2sys

Flux (> 1 TeV) ~3.5% Crab

No sign of a cut-off at high energy.

Fermi spectrum connects at lower energy

Electrons or hadrons?

Young (~330 yr) shell-type SNR

Discovered in TeV by HEGRA (232 hrs, 5 ), confirmed by MAGIC (47 hrs, 5.3 )

VERITAS: 22 hr data in 2007, 8.3


Acciari et al. 2009, submitted

Stage et al. 2006

Chandra

5’


First detected by MAGIC (2006)

Intensively observed by VERITAS, 2006-2009

Orbital modulation: GeV/TeV anticorrelation

Competition between IC and absorption?

Spectrum: Fermi cutoff ~6 GeV, VERITAS only 3 since Fermi launch

Magnetospheric emission?

Stellar weather?

Mirabel (Science 309, 714, 2006)

Accretion-powered Wind-driven

Fermi

VERITAS

FermiMAGIC/VERITAS


AGILE, Fermi report -ray activity from Cyg X-3

Fermi detects orbital period

AGILE detects 4 -ray flares, connects to jet formation

VERITAS will follow up in Spring!

VERITAS establishes -ray variability of HESS J0632+057

Unidentified TeV source in the Galactic plane – unresolved!

X-ray & radio sources coincident with a Be star (MWC148)

Swift: long-term X-ray variability

VERITAS, HESS leading MWL campaign to identify sourceAbdo et al. 2009 Science Express


IC 443: Extended and complicated Strong Fermi source: broadband spectral, morphological evolution

will be illuminating

SNR G106.3+2.7/Boomerang: Fermi, VERITAS, MILAGRO

Cas A: Best TeV spectrum to date Boon to modelers, especially combined with Fermi spectrum

Cygni: Emission not associated with large cloud to south Encountering increasing density to north?

LS I +61 303: GeV / TeV differences cooling mechanisms? GeV: detected at all phases, peaks at periastron

TeV: only clearly detected at apastron

HESS J0632+057: VERITAS established variability A new TeV binary system ?

Overall: Lack of strong (>5% Crab) sources (eg, PWNe) Sky survey is addressing this quantitatively


Broad-band -ray studies with VERITAS & Fermi Joint analysis (morphology, cross-correlation studies) with Fermi

data (funded GI Cycle II proposal)

Monitoring of LS I +61 303 (funded GI Cycle II proposal)

Deep observations & detailed studies of sources IC 443, SNR G106.3+2.7/Boomerang, Cygni, Cassiopeia A

MWL monitoring of known and candidate binary systems Cyg X-3, HESS J0632+057, LS I +61 303

Exploratory observations of candidate TeV emitters Supernova remnants interacting with molecular clouds

Nebulae associated with energetic pulsars

Follow-up of Fermi galactic sources Unidentifieds – use VERITAS angular resolution, lack of diffuse

Transients – very few so far!

response to SGR outbursts now following GRB protocol - fast



VERITAS Telescope Array

VERITAS: Four 12-m diameter atm. Cherenkov telescopes

F.L. Whipple Observatory (1.3 km altitude), AZ, USA

Staged construction, full sensitivity after Sept. 2007

Whipple 10m telescope on Mt. Hopkins (2.2 km altitude) 7km away


Instrument design:

Four 12-m telescopes, 3.5 FoV

FLWO, Mt. Hopkins, Az (1268m)

Fully operational Sept 2007

Performance:

3-level trigger (250 Hz rate)

~ 800 hrs/yr dark time, ~ 200 hrs/yr moon time

Energy threshold ~150 GeV (zenith)

Energy resolution ~ 15-20 %

Angular resolution ~ 0.1°

7km away

T1

Sep 2009

Sensitivity:

1% Crab < 50 hours (before T1 move)

1% Crab < 30 hours (after T1 move)

See poster by J. Perkins VERITAS T1 Relocation


Discovered by Whipple 10m in 1989

VERITAS: 5 in ~ 1 minute

Science Goals

Measure/limit extent of TeV emission

Stability of Crab emission (w/ MAGIC)

Probe correlated variability with Giant Radio Pulses (w/ ?)

Confirm pulsed emission

Measure spectrum to high energies

Point-source Sensitivity


Energy Range: 100 GeV – 30 TeV

(spectra >150 GeV)

Energy Resolution: 15% – 20%

Crab Rate ~ 40 / min (trigger)

Sensitivity: 5% Crab in < 2.5 h

1% Crab in < 50 h

Angular Resolution: r68 < 0.1o

Pointing Accuracy: < 50’’

Effective Area (std. cuts)

Energy Resolution

Angular Resolution


Currently the most sensitive VHE instrument in the world!


Energetic pulsar + wind nebula discovered in the error box of source 3EG J2227+6122.

Age ~ 10,000 years

E-dot = 2.2 × 1037 erg/s

Likely part of the larger SNR G106.3+2.7

Distance ~ 800 pc (Kothes et al. 2001)

Fermi: 0FGL J2229+6114

MILAGRO: Extended emission at ~35 TeV

1420 MHz: Effelsberg (Kothes et al.)

Boomerang PWN


Observations made in 2008 resolve TeV emission overlapping the radio shell of G106.3+2.7

7.3 σ detection in 33 hours (6.0 σ post-trials)

TeV emission is extended

Spans a 0.4 0.6 region

Peak is 0.4 away from PSR

Overlaps with region of high CO density

Excess Map

Black – Radio (DRAO)Circle – FGST Error BoxDot – Pulsar PositionPurple - 12CO Emission (FCRAO)Yellow star – 1AGL J2231+6109

Acciari et al. 2009, ApJ 703 L6.


Energy Spectrum

Integrate over 0.32 radius centered on emission peak

Well fit by a pure power law

Index: 2.3 ± 0.3stat ± 0.3sys

Flux (> 1 TeV) ~ 5% Crab

Extension of spectrum is consistent within errors with Milagro point at 35 TeV

Spectrum may favor hadronic origin?


Shell interacting with massive cloud

Age ~20-30 kyr, 0.75º

diameter

PWN at southern edge of shell

Discovered in GeV by EGRET

Now AGILE, Fermi

Discovered in TeV in 2007

by MAGIC (5.7 in 29 hrs)

by VERITAS (7.1/6.0 pre/post-trials in 15.9 hrs)

• Green – Radio

• Red – Optical

• Blue – X-rays

Troja et al. (2006)


Total live time: 37.9 hrs.

8.3 σ peak significance pre-trials

Power-law fit 0.3 – 2 TeV: Index: 2.99 ± 0.38stat ± 0.3sys

Flux (> 300 GeV) ~ 3.2% Crab

TeV emission may be





Window into propagation / diffusion of Cosmic Rays in interstellar medium

2-D Gaussian profile fit: Centroid: 06 16.9 +22 32.4 ± 0.03ºstat ± 0.07ºsys

Extension: σ ~ 0.16º ± 0.03ºstat ± 0.04ºsys

Red: Optical (DSS)Green: CO (Lee et al. 2010, in prep.)Yellow: VERITAS significance (4, 6 )

Acciari et al. 2009, ApJ 698 L133


TeV emission may be





Window into propagation / diffusion of Cosmic Rays in interstellar mediumAbdo et al. submitted


Efficient method of searching for new sources over a large region

Un-biased indication of source population

Southern hemisphere well-surveyed HESS Galactic plane survey: ~14 sources in initial survey

Best limits in northern hemisphere sky : HEGRA’s Galactic plane survey -2˚ < l < 85˚, flux upper limits: 15% Crab to several Crab

Size and choice of region based on VERITAS sensitivity and FOV Material distribution, density of potential TeV γ-ray emitters (SNRs,

PWNe, high E-dot pulsars, EGRET unidentified sources...)


Made possible by good off-axis sensitivity

Region covered: 67˚ < l < 82˚, -1˚ < b < 4˚

Available observing period: Apr-Jun, Sep-Nov

Effective exposure: ~6 hrs in base survey

112 hours in base survey + 56 hours followup.

Prior to Fall 2009

Eff

ective e

xposure

tim

e [m

in]

0.8˚

1.0˚

1.75˚


• Partial survey map, generated with standard threshold extended source analysis

• Includes all data in survey region taken to this point

• Exposure uneven due to followup (more intensive followup around VER J2019+407

than around TeV J2032+4130)

VER J2019+407

New VERITAS source

TeV J2032+4130

known source, first

detected by HEGRA

Likely associated: MGRO

J2031+41, 0FGL

J2032.2+4122 (LAT pulsar)

Detection: >5σ at nominal

position (no trials)

VER J2019+407


Early follow-up candidate

Recent (last 2 months) follow-up treated as an independent search 0.25˚ radius search region 0.6˚ wobble, position

indicated by earlier data

8.5σ (~7.5σ) pre- (post-) trials in Fall 2009 data alone

Position: RA: 304.97˚ ± 0.017˚stat Dec: 40.79˚ ± 0.023˚stat

Extension: 0.16˚ ± 0.028˚ (0.11˚ ± 0.027˚) for the major (minor) axis 2-d Gaussian fit to uncorrelated excess map (Fall 2009 data only)

Flux ~ few % Crab

Fall 2009 data only


No hotspots above 5σ post-trials in base survey

Preliminary Flux Limits (99% CL, all points in survey below 3σ) <3% Crab above 200 GeV (point source) <8.5% Crab above 200 GeV (0.2˚ radius extended source)

Possible indication that population in Cygnus region differs from inner galaxy HESS survey: out of 14 sources in -30˚<l< 30˚, saw 12 sources with fluxes ≥ 5%

Crab above 200 GeV expect ~2-3 in this survey

Detection of 2 sources with VERITAS survey technique and followup observations Discovery: VER J2019+407 TeV J2032

Further followup observations in survey region ongoing

Prospects for future: Spectra and energy-dependent morphology (VER J2019+407, TeV J2032+4130) Joint analysis (morphology, cross-correlation studies) with Fermi data


• Uchiyama et. al. ApJ, 571:866-875, 2002

– Soft X-ray emission belt (1-3 keV) from north to southeast

• shock interacting with cavity wall of ambient clouds?

– Suggests hard sources in north are shocked dense cloudlets

• Nonthermal bremsstrahlung of GeV electrons

Core of VERITAS excess

In 4-10 keV band, pair of faint hard X-ray

sources under core (part of C2, Uchiyama et

al.)

Uchiyama et. al.

ASCA X-ray map

4.85 GHz radio contours


Detection of 2 sources with VERITAS survey technique and followup observations Discovery: VER J2019+407

TeV J2032

Further followup observations in survey region ongoing.

Prospects for future: Spectra and energy-dependent morphology studies (VER J2019+407,

TeV J2032).

Joint analysis (morphology, cross-correlation studies) with Fermi data in the region.


Name Edot Dist Lg LX Lg/Edot LX / Edot LX /Lg

(erg/s) (kyr) (kpc) (10^34 erg/s) (10^35 erg/s) (%) (%)

Crab Nebula 460 1.2 2 8.6 190 0.02 4 220

G0.9+0.1 43 5.3 8.5 4.4 3.6 0.1 0.8 8

G21.5-0.9 33 4.85 4.7 0.72 2.2 0.02 0.7 30

G54.1+0.3 12 2.9 6.2 1.8 0.12 0.15 0.1 0.7

Kes75 8.1 0.7 7.5 2.5 2.4 0.3 19 18

Comparing properties to other young TeV pulsare wind nebulae:

Lg: Luminosity in 0.2-10 TeV band

LX: Luminosity in 0.5-8 keV band (Kargaltsev & Pavlov 2008)


Results: Unidentified Source

The Monoceros Loop SNR? Rosette Nebula region

Molecular gas,

NANTEN Galactic

plane survey

Radio observations

8.35 GHz

Green’s Catalog

position of SNR

30-150 kyrs old

Distance ~1.5 kpc

Interaction with the

Rosette nebula?

Puehlhofer et al. 2007 - First GLAST Symposium

HESS J0632+057: Only unidentified TeV source that is point-like

MWC 148



Prob. that VERITAS upper flux limits is consistent with HESS flux is 0.007% (~4 )

Ongoing analysis work: Is there a signal in energy range below 1 TeV?

Interpretation: Binary system? Coincident with Be star MWC 148

No companion yet detected; no information on period

Variable X-ray emission (Hinton 2009)

Acciari et al. 2009, in prep.



• Unidentified sources detected in

same FoV as the composite SNR

W44

– 9.1 hrs wobbling on W44

position, 4 hrs wobbling on UIDs

– J1857+026 possibly associated

with newly discovered radio

pulsar PSR J1856+0245

• W44: UL ~5% Crab

• J1857+026: 4-5 Sigma

• J1858+020: 7-8 Sigma


Results: Unidentified SourceTransient (E> 100 MeV) AGILE J2021+4024

Observations (initially under moonlight) triggered by AGILE. 3 Atels (#1492, 1547, 1585) issued on Apr 28, May 27, and Jun 23 2008 by AGILE

7 hour exposure (Apr 29 – May 6)

99% upper limit at 2% Crab flux above 300 GeV.

3EG J2020+4017

IGR J2018+4043


Results: Cas A

The non-thermal X-ray emission predominantly originates from filaments and knots in

the reverse-shock region of Cas A (Helder & Vink 2008).

The presence of a large flux of high-energy electrons in the reverse-shock region,

responsible for the non-thermal radio to X-ray emission, will also produce high-energy -

ray emission through non-thermal bremsstrahlung and IC scattering (Atoyan 2006).

Based on that leptonic emission, Cas A would appear in VERITAS data as a disk or ring-

like source with outer radius 2.5′ (Uchiyama & Aharonian 2000).

If, on the other hand, the VHE γ -ray emission from Cas A were dominated by 0 decay

produced in inelastic collisions of relativistic protons, the location of the particle-

acceleration site is less constrained by data in other wavebands.

The question of whether or not there is

a sufficiently high flux of Galactic

nuclear CRs resulting in a steady flux of

VHE –rays, remains one of the most

stimulating scientific questions of

ground-based –ray astronomy.

(Berezhko et al. 2003)


Results: Geminga

VERITAS Observations: 13.3 hours at high elevation

Upper Limit to steady emission(>300 GeV): <2x10-8 γ/m2/s (~1% Crab flux)

Upper Limit to pulsed emission(>300 GeV): <1x10-8 γ/m2/s (~0.5% of Crab flux)


Results: MGRO J1908+06HESS J1908+063

Needed a test case for Sky Survey extended source search, chose MGRO J1908+06/HESS J1908+063

MGRO unidentified source

80% of Crab Nebula Flux, <2.6diam. extension at 20 TeV

Detected in HESS galactic plane survey

14% Crab flux > 300 GeV

Source extension 0.21 0.07 (stat) 0.05 (sys)

VERITAS

Data taken under aegis of sky survey

~22h of 4-telescope data

4.85σ detection

~0.19 0.04 extension

position in agreement with HESS J1908+063


Published papers: 5 LS I +61 303 data from 2006/7 season , LS I +61 303 MWL (TeV

+ X-ray) 2007/8 season

IC 443, SNR G106.3+2.7/Boomerang

HESS J0632+057 variability

Submitted papers: 1 Cassiopeia A

Drafted papers: 1 PSR J1930+1852

Papers in preparation: 4 Sky Survey, Cygni , TEV J2032+4130

W44 / HESS J1857+026 / HESS J1858+020 region

Papers in development: 2 Supernova Remnant upper limits

Pulsar Wind Nebula upper limits


Two Key Science Projects:

Survey of Cygnus Region

Studies of Supernova Remnants and Pulsar Wind Nebulae

Merger of several inter-related science groups:

Sky Survey

SNRs & PWNe

Compact Objects

Unidentified Sources

Telecons ~ monthly to discuss observing proposals, results, papers, …


IC 443

SNR G106.3+2.7 / Boomerang

SNR G54.1+0.3 / PSR J1930+1852

Cassiopeia A



Summary

VERITAS is operating very well (> 95% uptime) with

two+ good years of data in hand.

Many new results, including:

• Discovery of -ray emission from starburst galaxy M82.

•New information on origins of cosmic rays.

• Stringent limits from Galactic plane survey.

• Detection of new TeV source near Cygni SNR, VER J2019+407

• Detection of 2 new PWN/SNR: G106.3+2.7, G54.1+0.3.

• Detailed studies of SNRs: IC 443 and Cas-A.

VERITAS Upgrade will significantly improve sensitivity.

T1 Relocation already has!

Broad-band studies (GeV – TeV) underway – much more to come.


IC 443: Extended and complicated Hints of energy-dependent morphology in TeV band

Strong Fermi source: broadband spectral, morphological evolution will be illuminating

Cas A: Best TeV spectrum to date Boon to modelers

Cygni: Emission not associated with large cloud to south Cloudlets to the north?

LS I +61 303: GeV / TeV differences cooling mechanisms? GeV: detected at all phases, peaks at periastron

TeV: only clearly detected at apastron

Rapid X-ray variability (doubling times short as 2 seconds!)

General: Lack of strong (>5% Crab) sources (eg, PWNe) Sky survey is addressing this quantitatively


Many of our sources show significant extent IC 443, Boomerang, MGRO J1908…

This matches HESS experience: Almost all Galactic sources (minus Crab, Cas A, binaries) are extended

Observing: Default 0.5º wobble may not be appropriate for Galactic sources where extent is a priori unknown Issue both for detection (potentially) and spectra (definitely)

Larger wobbles? Mini surveys?

Moonlight is fruitful for Galactic sources

PSR J1930, LS I +61 303

Analysis: More effort needed on extended sources Background models for detection, spectra

Handling of bright stars, angular resolution

Likelihood methods for extended sources?


Young (~330 yr), well studied shell-type SNR

Distance ~3.4 kpc

5-arcmin diameter

Comparable to TeV PSF

Discovered in TeV by HEGRA (232 hrs, 5 ), confirmed by MAGIC (47 hrs, 5.3 )

Stage et al. 2006 (Chandra, 7.3’ by 6.4’)


Solid: VERITAS

Dashed: HEGRA

Dotted: MAGIC

Index: 2.61 ± 0.24stat ± 0.2sys

Flux (> 1 TeV) ~3.5% Crab

No sign of a cut-off at high energy.

Fermi spectrum connects at lower energy

Electrons or hadrons?

VERITAS: 22 hr data in 2007, 8.3


Acciari et al. 2009, submitted

To be replaced by spectrum

including Fermi points


“Cousin of the Crab” X-ray jet/torus, no thermal shell

Age ~ 2900 years

E-dot = 1.2 × 1037 erg/s

Distance ~ 6.2 kpc

Lu et al. 2002 (Chandra/ACIS)


Hint of signal in 2007 moonlight data.

2008/09 follow-up yields a 7-σ detection in 31 hours

Location compatible with pulsar

Consistent with point source.

Acciari et al. (2009), in prep.


Cassiopeia A is a young SNR, ~ 320 yrs old

X-ray synchrotron (like SN 1006)

First SNR detected in TeV gamma rays! By HEGRA in 2001

since detected by VERITAS and MAGIC as well

Does it accelerate ions, or just electrons?

Chandra X-ray image

~ 5 arcmin

m m m m


Introduction

Survey of the Cygnus Region

Detections of SNRs and PWNe

-ray Binaries

Summary

Unidentifieds

HESS J1857+026 and HESS J1858+020 in the W44 region

MGRO J1908+063

AGILE transient J2021+4024

Northern PWN Survey Limits

3C 58, Geminga, others

Documents

Brian Humensky for the VERITAS Collaboration December 10 ...gibbs/VERITAS_OpsReview...Young, nonthermal X-ray SNR VHE spectrum is a power law to 5 TeV Study of gamma-ray binaries: