Jet-dominated advective systems of all mass scales

We show that the radio emission of black hole (BH) and neutron star (NS) X-ray binaries (XRBs) follows the analytical prediction of a jet model where the jet carries a constant fraction of the accretion power. The radio emission can therefore be used as a tracer of the accretion rate. This measure is normalised with efficiently radiating objects. As it is independent of the X-ray fluxes, the measure allows us to compare the accretion rate dependency of the bolometric X-ray luminosity of BHs and NSs. For NSs, it scales linearly with accretion rate while the scaling for BHs is quadratic - as expected for inefficient accretion flows. We find the same behaviour in AGN. This new approach uses the jet power to obtain the accretion rate. Thus, we know both the jet power and the radiated power of an accreting BH. This allows us to show that some accretion power is likely to be advected into the black hole, while the jet power dominates over the bolometric luminosity of a hard state BH.Comment: conference proceedings of the Sixth Microquasar workshop: Microquasars and Beyond, 18-22 September 2006 in Como, Italy (eds: T. Belloni et al. 2006

Nature and evolution of powerful radio galaxies and their link with the quasar luminosity function

Current wide-area radio surveys are dominated by active galactic nuclei, yet many of these sources have no identified optical counterparts. Here we investigate whether one can constrain the nature and properties of these sources, using Fanaroff-Riley type II (FRII) radio galaxies as probes. These sources are easy to identify since the angular separation of their lobes remains almost constant at some tens of arcseconds for z>1. Using a simple algorithm applied to the FIRST survey, we obtain the largest FRII sample to date, containing over ten thousand double-lobed sources. A subset of 459 sources is matched to SDSS quasars. This sample yields a statistically meaningful description of the fraction of quasars with lobes as a function of redshift and luminosity. This relation is combined with the bolometric quasar luminosity function, as derived from surveys at IR to hard X-ray frequencies, and a disc-lobe correlation to obtain a robust prediction for the density of FRIIs on the radio sky. We find that the observed density can be explained by the population of known quasars, implying that the majority of powerful jets originate from a radiatively efficient accretion flow with a linear jet-disc coupling. Finally, we show that high-redshift jets are more often quenched within 100 kpc, suggesting a higher efficiency of jet-induced feedback into their host galaxies.Comment: Accepted for publication in MNRA

The Power of Jets: New Clues from Radio Circular Polarization and X-rays

Jets are ubiquitous in accreting black holes. Often ignored, they may be a major contributor to the emitted spectral energy distribution for sub-Eddington black holes. For example, recent observations of radio-to-X-ray correlations and broad band spectra of X-ray binaries in the low/hard state can be explained by a significant synchrotron contribution from jets also to their IR-to-X-ray spectrum as proposed by Markoff, Falcke, Fender 2001. This model can also explain state-transitions from low/hard to high/soft states. Relativistic beaming of the jet X-ray emission could lead to the appearance of seemingly Super-Eddington X-rays sources in other galaxies. We show that a simple population synthesis model of X-ray binaries with relativistic beaming can well explain the currently found distribution of off-nucleus X-ray point sources in nearby galaxies. Specifically we suggest that the so-called ultra-luminous X-ray sources (ULXs, also IXOs) could well be relativistically beamed microblazars. The same model that can be used to explain X-ray binaries also fits Low-Luminosity AGN (LLAGN) and especially Sgr A* in the Galactic Center. The recent detection of significant circular polarization in AGN radio cores, ranging from bright quasars down to low-luminosity AGN like M81*, Sgr A* and even X-ray binaries, now places additional new constraints on the matter contents of such jets. The emerging picture are powerful jets with a mix of hot and cold matter, a net magnetic flux, and a stable magnetic north pole.Comment: to appear in: ``Lighthouses of the Universe'', Springer Verlag, ESO Astrophysics Symposia, Eds: R.Sunyaev, M.Gilfanov, E.Churazov, LaTex, 8 pages, 5 figures, also available at http://www.mpifr-bonn.mpg.de/staff/hfalcke/publications.html#lighthouse

Jet-dominated advective systems: radio and x-ray luminosity dependence on the accretion rate

We present a novel method to measure the accretion rate of radio emitting x-ray binaries (XRBs) and active galactic nuclei (AGN) independently of the x-ray luminosity. The radio emission of the jet is used as a tracer for the accretion rate and is normalised using sources of known accretion rates: island state neutron stars and efficiently radiating black holes close to a state transition. We show that the radio power in black holes and neutron stars is comparable for a given mass accretion rate and verify empirically the assumed analytic scaling of the radio luminosity with accretion rate. As our accretion measure is independent of the x-ray luminosities, we can search for radiatively inefficient accretion in black holes by comparing the x-ray luminosities with the accretion rate in XRBs and AGN. While the x-ray luminosity of efficiently radiating objects scales linearly with accretion rate, the scaling of hard state black holes is quadratical, in agreement with theoretical models. We show that the turnover from the inefficient quadratic scaling to the linear scaling has to occur at accretion rates of 1-10 % Eddington both in XRBs and AGN. The comparison of both accretion states supports the idea that in a black hole in the hard state some accretion power is advected into the black hole while the jet power exceeds the x-ray luminosity: these are therefore jet-dominated advective systems

Accretion states and radio loudness in active galactic nuclei: analogies with X-ray binaries

Hardness-intensity diagrams (HIDs) have been used with great success to study the accretion states and their connection to radio jets in x-ray binaries (XRBs). The analogy between XRBs and active galactic nuclei (AGN) suggests that similar diagrams may help to understand and identify accretion states in AGN and their connection to radio loudness. We construct "disc-fraction luminosity diagrams" (DFLDs) as a generalization of HIDs, which plot the intensity against the fraction of the disc contribution in the overall spectral energy distribution (SED). Using a sample of 4963 Sloan Digital Sky Survey (SDSS) quasars with ROSAT matches, we show empirically that an AGN is more likely to have a high radio:optical flux ratio when it has a high total luminosity or a large non-thermal contribution to the SED. We find that one has to consider at least two-dimensional diagrams to understand the radio loudness of AGN. To extend our DFLD to lower luminosities we also include a sample of low-luminosity AGN. Using a simulated population of XRBs we show that stellar and supermassive BHs populate similar regions in the DFLD and show similar radio/jet properties. This supports the idea the AGN and XRBs have the same accretion states and associated jet properties

Do BL Lac objects fit on the fundamental plane?

The fundamental plane of black hole accretion-a correlation between radio luminosity, X-ray luminosity, and black hole mass-expresses the connections between accretion physics over at least eight orders of magnitude in black hole mass. We first present an updated regression analysis of the fundamental plane utilizing a Bayesian approach. We then present new results on our attempts to place BL Lac objects on the fundamental plane. BL Lac objects are in-terpreted in the standard model as low-luminosity radio galaxies viewed nearly along the axis of a relativistic jet. They might be excellent high-mass analogs (˜108 -109 solar masses) to hard-state X-ray binaries because their spectral energy distributions are jet dominated. Also, they likely have weak broad emission line regions, meaning their environments are relatively un-complicated compared to other classes of Active Galactic Nuclei (AGN) with similarly massive black holes. We consider around 102 BL Lac objects here (taken from a much larger 723 object SDSS BL Lac sample) for which we measure black hole masses, and for which we have radio, optical, and X-ray flux measurements. Even just this subset of 102 BL Lac objects is larger than entire XRB/AGN samples used in previous fundamental plane studies. Our BL Lacs generally fit on the fundamental plane, albeit with scatter. We investigate potential sources of this scatter, such as the importance of relativistic beaming. We also discuss if objects deviate from the plane as a function of their synchrotron cutoff frequency, which could be interpreted as variations in the strengths of their broad emission line regions (i.e., environment) and/or in accretion rate

Jets: black holes and beyond

We review the topic of jets in the universe, starting with the early history. We focus on jets from X-ray binaries, discussing the contrasts between the jets seen from black holes and from neutron stars. We then show the implications of results on X-ray binaries for studies of active galactic nuclei, and other black holes not in binary systems, such as stellar-mass black holes accreting from molecular clouds, and intermediate-mass black holes accreting from the interstellar medium in globular clusters. We close by listing some open issues on the topic