Models of the compact jet in GRS 1915+105

Abstract

In this article, models are constructed of the compact jet in GRS 1915+105 during an epoch of optimal data capture. On 2003 April 2, 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 Very Long Baseline Array (VLBA) (8.3 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 (>1015 cm). This combined with the broad‐band coverage make this epoch the best suited for modelling the jet. The parametric method 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 disc photons by jet plasma provides the hard X‐ray power law. Unlike active galactic nucleus (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 ≈ 3–4 × 1038 erg s−1 if the hard X‐ray power‐law luminosity is from EIC in the jet and Q ≈ 2–9 × 1037 erg s−1 if the X‐rays are emitted from the accretion disc corona. These estimates indicate that the jet power can be as high as 60 per cent of the total X‐ray luminosity.

A Temporal Analysis Indicates a Mildly Relativistic Compact Jet in GRS 1915+105

“…The constraint, V app ≫ D/T ≈ 0.36c noted above (that is required to produce the temporal exponential decay) disagrees with the jet velocity found in Ribo et al (2004) by considering jet bilateral asymmetry due to Doppler abberation of an intrinsically bilaterally symmetric system One other curious feature of the slowly varying jet scenario is evident if the details of the power law models of Punsly (2011) are considered. The base of the jet that produces the majority of the 15 GHz flux density is located < 3 × 10 7 cm from the central black hole (see Table 1 and Figure 2 of Punsly (2011)). Considering the time scales for decay of 3.8 hrs and 8.6 hrs from Figure 2, turning down the power of the jet by moving plasma in the disk at the base of the jet corresponds to a rather suspect slow radial velocity of ∼ 10 3 cm/s.…”

“…In the context of GRS 1915+105, models based on Ghisellini et al (1985); Ghisellini and Maraschi (1989); Ghisellini et al (1996) were applied to the compact jet (Punsly 2011). The mod-els described the surface brightness profile of the compact jet considered here (in the next subsection and Figure 4) as well as the broadband spectral energy distribution.…”

“…One other curious feature of the slowly varying jet scenario is evident if the details of the power law models of Punsly (2011) are considered. The base of the jet that produces the majority of the 15 GHz flux density is located < 3 × 10 7 cm from the central black hole (see Table 1 and Figure 2 of Punsly (2011)).…”

“…As opposed to conical SSA jets, the properties of GRS 1915+105 are better explained with a structured jet (see e.g. Punsly (2011)). The X-ray luminosity of GRS 1915+105 is also one of the highest of any known Galactic black hole candidate (Done et al 2004).…”

RAiSE III: 3C radio AGN energetics and composition

“…The kinetic powers of AGN jets have previously been estimated using radio source dynamical models (Machalski et al 2004;Krause 2005;Shabala et al 2008;Punsly 2011;Turner & Shabala 2015), hot X-ray gas cavity observations (Rafferty et al 2006;Bîrzan et al 2008;Cavagnolo et al 2010), lobe expansion speeds using spectral fitting (Daly et al 2012), strong shocks around the lobes (Croston et al 2009), and measurements of the properties of the jet termination shocks (hotspots; . However, there is a lack of reliable and generally applicable methods to estimate jet power.…”