High-Energy Studies of Gamma-Ray Binaries

High-Energy Studies of Gamma-Ray Binaries

Valentí Bosch-RamonUniversitat de Barcelona

Exploring the Non-thermal Universe with Gamma Rays

On the occasion of the 60th birthday of Felix Aharonian

Barcelona, November 6 - 9, 2012

(Bosch-Ramon, Barkov,Khangulyan & Perucho 2012)

(Khangulyan, Aharonian &Bosch-Ramon 2008)

(Perucho & Bosch-Ramon 2012)

Gamma-Ray Binaries

RemarksThe production of gamma-ray emission in binary systems was for a long time an non-confirmed discovery but desired possibility.

During the last 10 years, a new population of compact and variable galactic sources has arised.These are powerful and very complex sources whose study requires multi-disciplinary approaches. Now this field is reaching maturity...

Felix has worked for long in the understanding of high-energy emission in microquasars and pulsar binary systems, and has open or strongly affected the development of

Observations

Numerical simulacions

Radiation processes

of these kind of objects.

Gamma-ray Binaries>10 Years Ago

(Paredes et al. 2000)

From the beginning of the 70s, gama-ray emission was reported from Cygnus X-3.

In the late 70s, in the Hermsen et al. COS B catalog, Gregory & Taylor found a strongly variable radio source, nowadays LS I +61 303

Maraschi & Treves 1981 propose a pulsar binary scenario for this source.

Levinson & Blandford propose galactic jets as gamma-ray sources.

In 1998, Atoyan & Aharonian present a complex multiwavelength blob model predicting/explaining gamma-ray flares from microquasars.

In 2000, Paredes et al. propose that a new ”microquasar”, LS 5039, may be behind an EGRET source.

Gamma-ray Binaries>10 Years Ago

Modeling of gamma-ray emission from binaries proceeds at a slow pace until the arrival of the present-generation Cherenkov instruments...

(Paredes, Romero, Bednarek, Dubus, Torres, Dermer-Böttcher, Neronov-Chernyakova...)

(Aharonian et al. 2006; Albert et al. 2006)

Electromagnetic radiation initiated by hadronic jets from microquasars

in the ISM(Bosch-Ramon, Aharonian & Paredes

2005)

The interaction of protons accelerated in the termination regions of microquasars with nearby molecular clouds may lead to “hot spots” in gamma rays and lower energy radiation.

Several cases of SNR-related CRs have been discovered, but young binary systems may be indirectly responsible of gamma-ray emission in some crowded and dense regions of the Galaxy..

On the formation of TeV radiation in LS 5039(Khangulyan, Aharonian & Bosch-Ramon 2008)

Transport of electrons of different energies,without adiabatic losses under low-B fields.

The accerelation efficiency depends on the accelerator size/location, the B-field, and the acceleration efficiency.

A 1-D emitter (not necessarily a microquasar)

On the formation of TeV radiation in LS 5039(Khangulyan, Aharonian & Bosch-Ramon 2008)

The geometry of the emitter, in particular the star / emitter / observer geometrical relation, and the emitter structure (transport), are crucial to characterize the formation of radiation in binary systems: IC emission and gammagamma absortion

On the formation of TeV radiation in LS 5039(Khangulyan, Aharonian & Bosch-Ramon 2008)

Non-thermal emission from secondary pairs in close TeV binary systems

(Bosch-Ramon, Khangulyan & Aharonian 2008a)

The environment of a TeV emitter in amassive binary, the stellar wind, will be populated with secondary pairs created in the stellar photon field.

The magnetic field strength, and secondarily its structure, play a very important role shaping the VHE and also lower energy spectrum.

Non-thermal emission from secondary pairs in close TeV binary systems

(Bosch-Ramon, Khangulyan & Aharonian 2008a)

Even moderate surface B-fields of the massive companion can imply enough synchrotron emission from secondaries to overcome a primary X-ray (and radio) emitter.

A significant amount of energy will be transported by the stellar wind out of the system.

However, adiabatic losses cannot be neglected, affecting mainly radio emission.

The magnetic field and the location of the TeV emitter in Cygnus X-1 and LS 5039

(Bosch-Ramon, Khangulyan & Aharonian 2008b)

Given the detection of TeV photons from certain orbital phases, one can derive strong constraints either in the location / extension of the emitter or the magnetic field.

Presently, we know that even when B is very low and cascades are effective, the detection of TeV photons imply a quite extended / peripheric emitter in LS 5039.

Study of the Spectral and Temporal Characteristics of X-Ray Emission of the Gamma-Ray Binary LS 5039 with Suzaku

(Takahashi et al. 2009)

The X-ray and TeV emitting electron energies and the spectra manifested a possible one-population origin, although the X-ray modulation may point to adiabatic losses.

GeV data would bring surprises pointing to a more complex emitter...

Study of the Spectral and Temporal Characteristics of X-Ray Emission of the Gamma-Ray Binary LS 5039 with Suzaku

(Takahashi et al. 2009)

The X-ray and TeV emitting electron energies and the spectra manifested a possible one-population origin, although the X-ray modulation may point to adiabatic losses.

GeV data would bring surprises pointing to a more complex emitter...

Gràcies Felix