The variable radio counterpart and possible large-scale jet of the new Z-source XTE J1701-462

We report radio observations, made with the Australia Telescope Compact Array, of the X-ray transient XTE J1701-462. This system has been classified as a new `Z' source, displaying characteristic patterns of behaviour probably associated with accretion onto a low magnetic field neutron star at close to the Eddington limit. The radio counterpart is highly variable, and was detected in six of sixteen observations over the period 2006 January -- April. The coupling of radio emission to X-ray state, despite limited sampling, appears to be similar to that of other `Z' sources, in that there is no radio emission on the flaring branch. The mean radio and X-ray luminosities are consistent with the other Z sources for a distance of 5--15 kpc. The radio spectrum is unusually flat, or even inverted, in contrast to the related sources, Sco X-1 and Cir X-1, which usually display an optically thin radio spectrum. Deep wide-field observations indicate an extended structure three arcminutes to the south which is aligned with the X-ray binary. This seems to represent a significant overdensity of radio sources for the field and so, although a background source remains a strong possibility, we consider it plausible that this is a large-scale jet associated with XTE J1701-462.Comment: Accepted for publication as a Letter in MNRA

The evolution of patent functions: New trends, main challenges and implications for firm strategy

Recent publications in the field of Intellectual Property (IP) have shown that the previous literature did not grasp how complex patents are. The goal of this paper is to present an overview of all identified functions of patents and of the main strategic implications of such a complex picture. We first survey the main patent functions : innovation protection, functions related to trade and finance, defensive roles, and patent as an input in the innovation process. We then define each function and analyse their main evolution trends in relation with the current environment. We finally identify the strategic implications of each function. We focus on the implications of the newly identified functions and on the interaction between the different functions.Patent ; Intellectual Property ; Strategic Management ; Functions ; Motives to patent

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

Spectral evolution of the microquasar XTE J1550-564 over its entire 2000 outburst

We report on RXTE observations of the microquasar XTE J1550-564 during a ~70 day outburst in April-June 2000. We study the evolution of the PCA+HEXTE spectra over the outburst. The source transited from an initial Low Hard State (LS), to an Intermediate State (IS), and then back to the LS. The source shows an hysteresis effect similar to what is observed in other sources, favoring a common origin for the state transitions in soft X-ray transients. The first transition occurs at a ~ constant 2-200 keV flux, which probably indicates a change in the relative importance of the emitting media. The second transition is more likely driven by a drop in the mass accretion rate. In both LS, the spectra are characterized by the presence of a strong power-law tail (Compton corona) with a variable high energy cut-off. During the IS, the spectra show the presence of a ~0.8 keV thermal component (accretion disk). We discuss the apparently independent evolution of the two media, and show that right after the X-ray maximum on MJD 51662, the decrease of the source luminosity is due to a decrease of the power-law luminosity, at a constant disk luminosity. This, together with the detection of radio emission (with a spectrum typical of optically thin synchrotron emission), may suggest that the corona is ejected and further detected as a discrete radio ejection.Comment: Accepted for publication in ApJ. 9 pages, 4 figures, abstract abridge

Revisiting the radio/X-ray flux correlation in the black hole V404 Cyg: from outburst to quiescence

We report results of Chandra X-ray and VLA radio observations of the Galactic accreting black hole V404 Cyg (GS 2023+338) in its quiescent state. V404 Cyg is detected at its faintest level of radio and X-ray emission with a 0.5-10 keV unabsorbed luminosity of 8.3 x 10^32 (d/3.5 kpc)^2 erg/s. The X-ray spectrum fit with an absorbed power-law model yields a photon index of 2.17 +/- 0.13. Contrary to previous findings, this clearly indicates that V404 Cyg undergoes - like most black holes in quiescence - a softening of its X-ray spectrum at very low luminosity compared to the standard hard state. The quiescent radio emission is consistent with the presence of self-absorbed compact jets. We have also reanalyzed archival data from the decay of the 1989 outburst of V404 Cyg in order to quantify more precisely the correlation between radio and X-ray emission in the hard state of V404 Cyg. We show that this correlation extends over five decades in X-ray flux and holds down to the quiescent state of V404 Cyg. The index of this correlation (~0.5) may suggest that synchrotron self-Compton emission is the dominant physical process at high energy in V404 Cyg. However, this index is also consistent with scale invariant jet models coupled to an inefficiently radiating accretion disc. We discuss the properties of the quiescent state of black holes and highlight the fact that some of their properties are different from the standard hard state.Comment: 7 pages, Accepted for publication in MNRA

On the Origin of Radio Emission in the X-ray States of XTE J1650-500 during the 2001-2002 Outburst

We report on simultaneous radio and X-ray observations of the black hole candidate XTE J1650-500 during the course of its 2001-2002 outburst. The scheduling of the observations allowed us to sample the properties of XTE J1650-50 in different X-ray spectral states, namely the hard state, the steep power-law state and the thermal dominant state, according to the recent spectral classification of McClintock & Remillard. The hard state is consistent with a compact jet dominating the spectral energy distribution at radio frequencies; however, the current data suggest that its contribution as direct synchrotron emission at higher energies may not be significant. In that case, XTE J1650-50 may be dominated by Compton processes (either inverse Comptonization of thermal disk photons and/or SSC from the base of the compact jet) in the X-ray regime. We, surprisingly, detect a faint level of radio emission in the thermal dominant state that may be consistent with the emission of previously ejected material interacting with the interstellar medium, similar (but on a smaller angular scale) to what was observed in XTE J1550-564 by Corbel and co-workers. Based on the properties of radio emission in the steep power-law state of XTE J1650-50, and taking into account the behavior of other black hole candidates (namely GX 339-4, XTE J1550-564, and XTE J1859+226) while in the intermediate and steep power-law states, we are able to present a general pattern of behavior for the origin of radio emission in these two states that could be important for understanding the accretion-ejection coupling very close to the black hole event horizon.Comment: Accepted for publication in The Astrophysical Journal. 33 pages, 10 figure