The GeV-TeV connection… and Supernova remnants, Pulsar Wind Nebulae and other Galactic sources

S. Funk, Kavli Institute for Astroparticle Physics & Cosmology, Stanford & SLAC

Start to connect LAT to TeV sources

will talk about what we knew before the LAT, what we expect and some very early results ...

The GeV-TeV connection

Stunning diversity of astrophysical TeV accelerators

Patchy observations apart from scan of Galactic plane (l=+-60, b = +-5)

Typical energy flux densities: 10-12 ergs cm-2 s-1 (1-10 TeV) 1 degree

X γ

x0.5x0.5

Aharonian et al., Nature, 439, 695 (2006)

Comparing TeV sources to EGRET

Hints for GeV emission from EGRET for some of the most prominent and brightest TeV sources

Galactic Center

RX J1713.7-3946

LS 5039

Kookaburra, IC 443, HESS J1825-178

More on this from Fermi-LAT

GLAST (IC)

GLAST (π0)

HESS

Reimer & Funk, ASSci, 309, 203 (2006)

SF,

Rei

mer

, O.,

Torr

es, D

., H

into

n, J

. ApJ

679

, 129

9 (2

008)

Aharonian et al., A&A 460, 365 (2006)

Comparing TeV sources to EGRET

EGRET: Energy flux (1-10 GeV)H.E.S.S.: Energy flux (1-10 TeV)GLAST: Sensitivity (1-yr) above 1 GeV (l=10, b=0)

SF,

Rei

mer

, O.,

Torr

es, D

., H

into

n, J

. ApJ

679

, 129

9 (2

008)

Instrumental parametersDifferential sensitivity significantly better in TeV instrumentsAll sky coverage for Fermi-LAT vs patches of the skyAngular resolution: only comparable at the high-energy endDiffuse model is additional complication for Fermi-LAT

SF,

Rei

mer

, O.,

Torr

es, D

., H

into

n, J

. ApJ

679

, 129

9 (2

008)

-4

-2

0

2

4

1015202530

3EG J1812-1316

3EG J1823-1314

3EG J1824-1514

3EG J1826-1302

3EG J1837-0423

3EG J1837-0606

HESS J1809-193

HESS J1813-178

HESS J1825-137 HESS J1826-148

HESS J1834-087

HESS J1837-069

-4

-2

0

2

4

-10-50510

3EG J1718-3313

3EG J1734-3232

3EG J1736-2908

3EG J1744-3011

3EG J1746-28513EG J1800-2338

3EG J1809-2328

HESS J1745-290

HESS J1745-303

HESS J1747-281

HESS J1800-240

HESS J1801-233

HESS J1804-216

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3EG J1639-4702

3EG J1655-4554

3EG J1710-4439

3EG J1714-3857

HESS J1614-518

HESS J1616-508HESS J1632-478HESS J1634-472

HESS J1640-465HESS J1702-420

HESS J1708-410

HESS J1713-381

HESS J1713-395

HESS J1718-385

)!Galactic Longitude (

Before Fermi-LATSystematic study in inner Galaxy between EGRET and H.E.S.S.

Check whether H.E.S.S. src is within EGRET contour

0 sources within 68% (chance coinc.: 0.5)

2 sources within 95% (chance coinc.: 1.4)

3 sources within 99%(chance coinc.: 2.5)

No coincidenceWithin 95%Within 99%

SF,

Rei

mer

, O.,

Torr

es, D

., H

into

n, J

. ApJ

679

, 129

9 (2

008)

Spectral connectionFor some of the positionally coincident sources there is a good spectral match

For some sources H.E.S.S. data put severe constraints on emission model

Fermi-LAT will measure through whole band

SF,

Rei

mer

, O.,

Torr

es, D

., H

into

n, J

. ApJ

679

, 129

9 (2

008)

Spectral connectionFor some of the positionally coincident sources there is a good spectral match

For some sources H.E.S.S. data put severe constraints on emission model

Fermi-LAT will measure through whole band

SF,

Rei

mer

, O.,

Torr

es, D

., H

into

n, J

. ApJ

679

, 129

9 (2

008)

Physical expectation

For IC sources a GeV-TeV connection is rather unlikely (need old source or high B-field)

For pion-decay: connection natural, but remember the difference in energy flux sensitivity

SF,

Rei

mer

, O.,

Torr

es, D

., H

into

n, J

. ApJ

679

, 129

9 (2

008)

Physical expectation

For IC sources a GeV-TeV connection is rather unlikely (need old source or high B-field)

For pion-decay: connection natural, but remember the difference in energy flux sensitivity

SF,

Rei

mer

, O.,

Torr

es, D

., H

into

n, J

. ApJ

679

, 129

9 (2

008)

The 3-month Fermi-LAT data

Fermi all-sky data allows for systematic study with TeV data.

Identified sources are AGN, Pulsars, LMC, high-mass X-ray binaries, the Earth, the Sun and the Moon

The Inner Galaxy

3 sources within 95% EGRET contour

Now with the LAT:

Confirm 2 of the 3

LS 5039

W28 SNR

+ GC source

+ HESS J1616-508

+ HESS J1834-087

+ HESS J1804-216

Beyond Inner Galaxy:

LS I61+303

IC443, ...

No coincidenceWithin 95%Within 99%

The Inner Galaxy

3 sources within 95% EGRET contour

Now with the LAT:

Confirm 2 of the 3

LS 5039

W28 SNR

+ GC source

+ HESS J1616-508

+ HESS J1834-087

+ HESS J1804-216

Beyond Inner Galaxy:

LS I61+303

IC443, ...

No coincidenceWithin 95%Within 99%

Coincidences with SNRs / PWNePositional coincident sources with SNRs and PWNe such as:

W28, W41, W51, IC443, Kookaburra, ...

As seen for CTA 1 and many others, the LAT detects many pulsars

Pulsed emission and extension analysis crucial for association

Abd

o et

al,

Sci

ence

, 322

, 121

8 (2

008)

... but probably not young SNRsBrightest young TeV SNR (RX J1713.7-3946) not in the bright source list (same for Cas A, RCW 86, Vela Jr., SN 1006)

Remember difference in energy flux sensitivity between Fermi-LAT and TeV telescopes

Old SNRs are preferred targets (lots of GeV-emitting protons still there) A

haro

nian

& A

toya

n, A

&A

309

, 917

(199

6)

The Crab Pulsar and Its Nebula

Most prominent example: Crab Nebula

Clearly detected in off-pulse emission

Spectrum matches the TeV spectrum

All phases

Off-pulseco

urte

sy M

.H. G

rond

in (L

AT-C

olla

bora

tion)

cour

tesy

M.H

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ndin

(LAT

-Col

labo

ratio

n)

cour

tesy

M.H

. Gro

ndin

(LAT

-Col

labo

ratio

n)

The Crab Pulsar and Its Nebula

Most prominent example: Crab Nebula

Clearly detected in off-pulse emission

Spectrum seems to connect nicely to the TeV spectrum

cour

tesy

M.H

. Gro

ndin

(LAT

-Col

labo

ratio

n)

cour

tesy

M.H

. Gro

ndin

(LAT

-Col

labo

ratio

n)

-4

-2

0

2

4

1015202530

3EG J1812-1316

3EG J1823-1314

3EG J1824-1514

3EG J1826-1302

3EG J1837-0423

3EG J1837-0606

HESS J1809-193

HESS J1813-178

HESS J1825-137 HESS J1826-148

HESS J1834-087

HESS J1837-069

LAT PSR J1826-1256

LS 5039

-4

-2

0

2

4

-10-50510

3EG J1718-3313

3EG J1734-3232

3EG J1736-2908

3EG J1744-3011

3EG J1746-28513EG J1800-2338

3EG J1809-2328

HESS J1745-290

HESS J1745-303

HESS J1747-281

HESS J1800-240

HESS J1801-233

HESS J1804-216

LAT PSR J1732-31

LAT PSR J1809-2332

3503550510

)!G

ala

cti

c L

ati

tud

e (

-4

-2

0

2

4

330335340345350

3EG J1639-4702

3EG J1655-4554

3EG J1710-4439

3EG J1714-3857

HESS J1614-518

HESS J1616-508HESS J1632-478HESS J1634-472

HESS J1640-465HESS J1702-420

HESS J1708-410

HESS J1713-381

HESS J1713-395

HESS J1718-385

PSR J1709-4429

)!Galactic Longitude (

Summary

We have just started the process of systematically comparing the GeV to TeV sky

Bright TeV sources might not be bright GeV sources (and vice versa)

Young SNRs not in bright source list

Many pulsars, need extension measurement for association

… exciting times ahead of us