observations of supernova remnants with veritas...veritas accumulated 2~3 times larger data for tev...

Observations of Supernova Remnants with VERITAS

Presented by Nahee Park

Thursday, May 8, 14

What do we want to learn?Are SNRs the main accelerators of the Galactic cosmic rays?

Efficiency of cosmic-ray acceleration?

Maximum energy that can be accelerated in SNRs?

Compiled data up to Jan. 2010 from CR database ( A.W.Strong et al, 2009 ICRC)Ackerman et al (2013)

Tycho

Morlino & Caprioli (2012)

Thursday, May 8, 14

What do we want to learn? (2)Study of the gamma-ray emissions from SNRs

Evolution of the SNRs as CR accelerators?

Difference depending on the environments & SNR types?

Resolving different components in SED?

Properties of escaping CRsCRs with higher energy escape first.

Possible high energy gamma-ray emissions from nearby MC?(e.g. W44 & W28)

Gamma-ray observations of SNRs provide a unique window - to study the acceleration & propagation of CRs - to study the environments & properties of SNRs

Thursday, May 8, 14

TeV SNRs

http://tevcat.uchicago.edu

IC 443

Tycho

Cas A

VER J2019+407

VER J2227+608

W51CW49B

MGRO J1908+06

in Northern sky

Thursday, May 8, 14

VERITAS SNR ProgramDeep observation of TeV SNRs

Cassiopeia A

Tycho

IC 443

Study of unidentified TeV sources with nearby SNRsVER J2019+407(γCygni)

MGRO J1908+06

VER J2227+608 (SNR G106.3+2.7)

Search for the discoveriesFermi SNR searching : W44, CTB109, etc

SNRs located nearby MC : VRO42.05.01, HB3, etc

Strong radio SNRs : W63, etc

Thursday, May 8, 14

Deep ObservationsEstimated results (calculated by Igor Telezhinsky)

Cass

iopeia

A

Tych

o

Thursday, May 8, 14

Deep ObservationsEstimated results (calculated by Igor Telezhinsky)

Cass

iopeia

A

Tych

o

Thursday, May 8, 14

IC 443MC interacting, nearby SNR

Two shells expanding to different density regions

OH masers

Distance ~ 1.5 kpc

PWN in the southern part

With TeV gamma-ray observations,Study CR diffusion

Morphology studies with deeper exposure

Estimate the flux from PWN

CXOU J061705.3+222127

Acciari et al (2009)

Ackerman et al (2013)

Thursday, May 8, 14

Cassiopeia AA historic, core-collapse SNR

Age : ~ 350 years, distance : ~ 3.4 kpc

Non-thermal X-ray emissions fromboth forward & reverse shocks

With TeV gamma-ray observations,Study the origin of gamma-ray emissions

Leptonic vs. hadronic

Contributions from reverse shock

Estimate the maximum energy of CRs

Yuan et al (2013)

Abdo et al (2010)

Thursday, May 8, 14

TychoA historical, Type Ia SNR

Age : ~440 yr, distance : 2~5 kpc

Exploded in relatively clean environment

Nearby MC in NE side

Hint of density gradient of ISM

Complicated structures in X-ray

Thin filaments, bright strips

With TeV gamma-ray observations,Determine the origin of the emission: MC vs. shell

Estimate the maximum energy of CRs

Study the acceleration theory in detail

e.g. Understanding a softer spectral index measured by Fermi-VERITAS

Acciari et al (2011)

Morlino & Caprioli (2012)

Thursday, May 8, 14

Tycho (2)Provide a laboratory to test various theoretical models

Thursday, May 8, 14

Tycho (2)Provide a laboratory to test various theoretical models

Thursday, May 8, 14

Observational StatusVERITAS accumulated 2~3 times larger data for TeV SNRssince the first reports of detections

Tycho

~ 140 hours ( from 67 hours )

Cassiopeia A

~ 100 hours ( from 22 hours )

Large zenith angle observation : increase of effective area for higher energy

IC 443

~ 90 hours ( from 37 hours )

Thursday, May 8, 14

Study of unidenti!ed TeV sourcesVER J2019+407

Coincide with NW shell of γCygni, Located within the Fermi cocoon

c.f. Fermi : extended emission from the entire remnant

MGRO J1908+06Partially coincide with SNR G40.5-0.5

Interaction of the pulsar wind with nearby molecular clouds or the SNR shock?

PWNe of PSR J1907+0602 & undetected pulsar?

VER J2227+608Coincide with SNR G106.3+2.7 & Milagro C4

PWN(PSR J2229+6114)/SNR(G106.3+2.7) complex?

Thursday, May 8, 14

Search for other TeV SNRsFermi-bright SNR search

W44

Search for SNRs nearby MC (w/ potential Fermi source)

HB3/W3 complex

VRO 42.05.01

CTB 109

Search for emissions from other FoVs3C396, 3C397, Kes79, HC40...

Thursday, May 8, 14

Future planLong term plan

What is the best way for VERITAS to contribute to SNR studies in next 3~5 years?

Collaboration with other gamma-ray experiments

Fermi

HAWC

Thursday, May 8, 14