95 research outputs found
Relativistic Jets in the RXTE Era
Since the launch of the Rossi X-ray Timing Explorer in 1995 our understanding
of jetted outflows has significantly improved. Indeed, relativistic jets are
now believed to be a fairly ubiquitous property of accreting compact objects,
that are intimately coupled with the accretion history. In this review, we
summarize the observational connections in X-ray binaries between accretion
flows and relativistic outflows (especially the relation with the X-ray
states). We emphasize those aspects that have significantly benefited from the
RXTE experiment, including the role that jets could play at high energies. We
also review recent observations of large scale relativistic jets that could
point to their long term effects on the interstellar medium.Comment: Published, 8 pages, 10 figures. N.B.: the most up to date version of
the relation of radio emission with X-ray states in astro-ph/040915
Radio Emission from an Ultraluminous X-Ray Source
The physical nature of ultraluminous x-ray sources is uncertain. Stellar mass
black holes with beamed radiation and intermediate mass black holes with
isotropic radiation are two plausible explanations. We discovered radio
emission from an ultraluminous x-ray source in the dwarf irregular galaxy NGC
5408. The x-ray, radio and optical fluxes as well as the x-ray spectral shape
are consistent with beamed relativistic jet emission from an accreting stellar
black hole. If confirmed, this would suggest that the ultraluminous x-ray
sources may be stellar-mass rather than intermediate mass black holes. However,
interpretation of the source as a jet-producing intermediate-mass black hole
cannot be ruled out at this time.Comment: 8 pages, one color figure. appeared in Science 299: 365-367 (January
17, 2003
Galactic black holes in the hard state, a multiwavelength view of accretion and ejection
The canonical hard state is associated with emission from all three fundamental accretion components: the accretion disk, the hot accretion disk corona and the jet. On top of these, the hard state also hosts very rich temporal variability properties (low frequency QPOs in the PDS, time lags, long time scale evolution). Our group has been working on the major questions of the hard state both observationally (with multi-wavelength campaigns using RXTE, SWIFT, SUZAKU, SPITZER, VLA, ATCA, SMARTS) and theoretically (through jet models that can fit entire SEDs). Through spectral and temporal analysis we seek to determine the geometry of accretion components, and relate the geometry to the formation and emission from a jet. In this presentation I will review the recent
contributions of our group to the field, including the SWIFT results on the disk geometry at low accretion rates, the jet model fits to the hard state SEDs (including SPITZER data) of GRO J 1655-40, and the final results on the evolution of spectral (including X-ray, radio and infrared) and temporal
properties of selected black holes in the hard states. I will also talk about impact of ASTROSAT to the science objectives of our group
Is the `IR Coincidence' Just That?
(Abridged) Motch (1985) suggested that in the hard state of GX 339-4 the soft
X-ray power-law extrapolated backward in energy agrees with the IR flux. Corbel
& Fender (2002) showed that the hard state radio power-law extrapolated forward
in energy meets the extrapolated X-ray power-law at an IR break, which was
explicitly observed twice in GX 339-4. This `IR coincidence' has been cited as
further evidence that a jet might make a significant contribution to the X-rays
in hard state systems. We explore this hypothesis with a series of simultaneous
radio/X-ray observations of GX 339-4, taken during its 1997, 1999, and 2002
hard states. We fit these spectra, in detector space, with a simple, but
remarkably successful, doubly broken power-law that requires an IR spectral
break. For these observations, the break position and the integrated radio/IR
flux have stronger dependences upon the X-rays than the simplest jet
predictions. If one allows for a softening of the X-ray power law with
increasing flux, then the jet model agrees with the correlation. We also find
evidence that the radio/X-ray fcorrelation previously observed in GX 339-4
shows a `parallel track' for the 2002 hard state. The slope of the 2002
correlation is consistent with prior observations; however, the radio amplitude
is reduced. We then examine the correlation in Cyg X-1 through the use of radio
data, obtained with the Ryle radio telescope, and RXTE data, from the ASM and
pointed observations. We again find evidence of `parallel tracks', and here
they are associated with `failed transitions' to the soft state. We also find
that for Cyg X-1 the radio flux is more fundamentally correlated with the hard
X-ray flux.Comment: To Appear in the July 2005 Astrophysical Journal; 9 Pages, uses
emulateapj.st
Connections between jet formation and multiwavelength spectral evolution in black hole transients
Multiwavelength observations are the key to understand conditions of jet formation in Galactic black hole transient (GBHT) systems. By studying radio and optical-infrared evolution of such systems during outburst decays, the compact jet formation can be traced. Comparing this with X-ray spectral and timing evolution we can obtain physical and geometrical conditions for jet formation, and study the contribution of jets to X-ray emission. In this work, first X-ray evolution - jet relation for XTE J1752-223 will be discussed. This source had very good coverage in X-rays, optical, infrared and radio. A long exposure with INTEGRAL also allowed us to study gamma-ray behavior after the jet turns on. We will also show results from the analysis of data from GX 339-4 in the hard state with SUZAKU at low flux levels. The fits to iron line fluorescence emission show that the inner disk radius increases by a factor of >27 with respect to radii in bright states. This result, along with other disk radius measurements in the hard state will be discussed within the context of conditions for launching and sustaining jets
Spectral State Transitions of the Ultraluminous X-ray Source IC 342 X-1
We observed the Ultraluminous X-ray Source IC 342 X-1 simultaneously in X-ray
and radio with Chandra and the JVLA to investigate previously reported
unresolved radio emission coincident with the ULX. The Chandra data reveal a
spectrum that is much softer than observed previously and is well modelled by a
thermal accretion disc spectrum. No significant radio emission above the rms
noise level was observed within the region of the ULX, consistent with the
interpretation as a thermal state though other states cannot be entirely ruled
out with the current data. We estimate the mass of the black hole using the
modelled inner disc temperature to be based on a Shakura-Sunyaev
disc model. Through a study of the hardness and high-energy curvature of
available X-ray observations, we find that the accretion state of X-1 is not
determined by luminosity alone.Comment: 10 pages, 5 Figures. MNRAS: Accepted 2014 July 2
Radio Detections During Two State Transitions of the Intermediate Mass Black Hole HLX-1
Relativistic jets are streams of plasma moving at appreciable fractions of
the speed of light. They have been observed from stellar mass black holes
(320 solar masses, M) as well as supermassive black holes
(1010 M) found in the centres of most galaxies. Jets
should also be produced by intermediate mass black holes (1010
M), although evidence for this third class of black hole has until
recently been weak. We report the detection of transient radio emission at the
location of the intermediate mass black hole candidate ESO 243-49 HLX-1, which
is consistent with a discrete jet ejection event. These observations also allow
us to refine the mass estimate of the black hole to be between 9
10 M and 9 10 M.Comment: 13 pages, includes supplementary online information. Published in
Science in August 201
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