Models of the Compact Jet in GRS 1915+105

TL;DR

This paper models the compact jet in GRS 1915+105 during a high-quality observational epoch, using a parametric approach to understand jet structure and power, with implications for jet emission mechanisms.

Contribution

It applies a parametric modeling method from extragalactic jets to the microquasar GRS 1915+105, revealing the jet's stratified structure and estimating its power relative to X-ray luminosity.

Findings

Jet power estimated at 2-4 x 10^{38} ergs/sec.

Jet must be highly stratified transversely.

Jet power can reach up to 60% of X-ray luminosity.

Abstract

In this article, models are constructed of the compact jet in GRS 1915+105 during an epoch of optimal data capture. On April 02, 2003, the object was observed in the hard X-ray/soft gamma ray band (INTEGRAL), hard X-ray band (RXTE), near IR (ESO/New Technology Telescope) and the VLBA (8.3 GHz and 15 GHz). The source was in a so-called "high plateau state." The large radio flux provides high signal to noise ratios in the radio images. Thus, one can image the jet out to large distances ($ > 10^{15}$ cm). This combined with the broadband coverage make this epoch the best suited for modeling the jet. The parametric method developed in the papers \cite{ghi85,ghi89,ghi96,sam97} that has been successfully utilized in the realm of extragalactic radio jets is implemented. The basic model is one where external inverse Compton (EIC) scattering of accretion disk photons by jet plasma provides the hard X-ray powerlaw. Unlike AGN jets, it is found that the radio jet must be highly stratified in the transverse direction in order to produce the observed surface brightness distribution in the radio images. Various jet models are considered. The jet power is $Q \approx 3-4 \times 10^{38}$ ergs/sec if the hard X-ray powerlaw luminosity is from EIC in the jet and $Q \approx 2 - 9 \times 10^{37}$ ergs/sec if the X-rays are emitted from the accretion disk corona. These estimates indicate that the jet power can be as high as 60% of the total X-ray luminosity.