# Presentation: 725679

## Future Observations of Galactic Compact Sources

- Philip Kaaret, Reshmi Mukherjee, Martin Pohl, Ken Ragan, Brenda Dingus, Jamie Holder, John Finley, Rene Ong, Stephan LeBohec

-  **Supernova remnants and acceleration of cosmic rays**
** ****Particle acceleration by black holes and neutron stars**
** ****Unidentified GeV/TeV sources**
** ****Search for new Galactic sources**

## Cosmic Rays

-  The origin of cosmic rays is one of the oldest and most challenging problems in astroparticle physics
-  There is clear evidence for acceleration of electrons to ~10 TeV in supernova remnants, pulsar wind nebulae, and black hole jets.
-  Evidence for acceleration of hadronic cosmic rays is ambiguous at best.  Not clear if SNR are dominant source or if PWN, black hole jets, or OB winds are important.
-  Ability to distinguish TeV photons produced by hadronic vs leptonic cosmic rays is key.  Hadronically produced emission should correlate with target material.

## IC 443

- <date/time>

- Near IR image of IC 443
- Red at South is 2.12 m H2 molecular line excited by the supernova shock.
- Blue is mainly [Fe II].
- Need to resolve remnant on physical scale of target material.

**6**** ́**

## SN 1006

- <date/time>

- X-Ray (2-4.5 keV) and radio images of SN 1006.
- Nonthermal X-ray emission gives evidence for acceleration of electrons to 10-100 TeV.
- Mapping of TeV photons from inverse-Compton scattering would determine the magnetic field and the maximum electron energy.
- Should also constrain diffusion and lifetime of the electrons.

**6**** ́**

## Cosmic Ray Acceleration

- Key goal is to unambiguously disentangle TeV emission from electronic versus hadronic cosmic rays, imaging appears to be best method.
- Observe SNR (production sites?) and giant molecular clouds (passive targets) to map distribution.
- Non-detection of hadronically produced -rays would require either a very steep source spectrum, inconsistent with that needed to produce the local spectrum, or a greatly reduced cosmic-ray intensity, inconsistent with the energy budget for cosmic rays.
- Either possibilities would lead to serious revisions in our understanding of the origin of cosmic rays.

## Particle Acceleration by Black Holes

-  Jets are ubiquitous in accreting Galactic black holes and likely play a major, yet poorly understood, role in the overall accretion process.
-  X-ray observations provide clear evidence for acceleration of electrons to 10-100 TeV.
-  Detection of TeV photons constrain the highest energy particles and place strong constraints on the acceleration mechanism.

## XTE J1550-564

- Radio and X-ray from a single population of electrons.
- Maximum energy:  e > 2 x107

-  = 0.66 ± 0.01

## Microquasar Detected at TeV

***LS 5039***

**~1.4% Crab (>100 GeV)**

- Slide by Wei Cui

## TeV emission from LS 5039

- TeV photons may arise from inverse-Compton scattering of electrons on photons from the O6.5V companion star or interactions of protons accelerated in the jet with the stellar wind.
- The luminosity in the TeV band indicates an extremely powerful outflow.  For 1% acceleration efficiency, the jet kinetic power must be ~10 the X-ray luminosity.
- This result has major implications for our understanding of accretion flows near black holes.

## TeV emission from microquasars

- LS 5039 has a high mass companion star and a continuous jet.
- Additional systems should be studied and their energy spectra accurately measured.
- More of microquasars have low mass companion stars and intermittent jets.  Need all-sky coverage or frequent monitoring.

## Particle Acceleration by Neutron Stars

-  TeV observations of pulsar wind nebula will help determine the precise mechanism by which the pulsar spin-down energy is dissipated, the maximum particle energy, the particle injection rate, and the strength of the nebular magnetic field.
-  PWN are, probably, the most common TeV source.
-  High angular resolution measurements of several nebula and statistics on a large set of nebula are needed.
-  HESS detection of PSR B1259-63 provides a different probe of particle acceleration by young, rotation-powered pulsars.

## Unidentified Gamma-Ray Sources

- EGRET produced a large set of unID sources, HESS has found several, GLAST will like find many (the majority of its sources)
- Possible sources:
- Dark Accelerators
- Gamma-Ray Burst Remnants
- Completely new objects

## Unidentified Gamma-Ray Sources

- Requirements:
- High angular resolution
- Source location accuracy to < 1 ́, prefer better
- Extension of energy band to overlap with GLAST
- High count rate for pulsation searches

## Search for New Gamma-Ray Sources

- Flux sensitivity of 10-14 erg/cm2/s corresponds to luminosity of 1032 erg/s at 10 kpc, 1031 erg/s at 3 kpc.
- This is comparable to the quiescent X-ray luminosity of black hole and neutron star binaries, the expected TeV luminosity of individual giant molecular clouds, luminosity of isolated pulsars.
- A survey with such sensitivity could lead to the detection of hundreds of new Galactic sources.
- Wide field of view is needed.

## Testing Lorentz Symmetry

- TeV measurements of the spectrum of the Crab nebula constrain vacuum Cherenkov radiation (Jacobsen et al. 2001).
- The absence of energy dependent time delays in the GeV band from pulsars constraint Lorentz violations (Kaaret 1999).

## Goals for Future Observations

- Cosmic rays: good angular resolution (1 ́-6 ́), high photon counting rate.
- Jets: good sensitivity (< 1% Crab in few hours), all-sky coverage would be a plus.
- Unidentified sources: good angular resolution, position centroids to < 1 ́, lowest possible energy threshold.
- New sources, flux sensitivity of 10-14 erg/cm2/s and field of view > 5o.