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Register a new userUltra-deep mid-IR survey of a lensing cluster
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We present the first results of mid-infrared (MIR) ultra-deep observations towards the lensing cluster Abell 2390 using the ISOCAM infrared camera on-board ESAs Infrared Space Observatory (ISO) satellite. They reveal a large number of luminous MIR sources. Optical and near-infrared (NIR) cross-identification suggests that almost all 15 microns sources and about half of the 7 microns are identified with distant lensed galaxies. Thanks to the gravitational amplification these sources constitute the faintest MIR sources detected. We confirm that the number counts derived at 15 microns show a clear excess of sources with respect to the predictions of a no-evolution model. The possible extension of the NGST instrumentation from the near-IR (1-5 microns) to the thermal infrared, up to 20 microns (as suggested by the NGST task group report, October 1997) would permit study of this new population of dust-enshrouded AGN/starburst galaxies detected by ISOCAM, up to very high redshifts and with vastly improved spatial resolution. The existence of this population demonstrats that the discrimination of dust contributions, possible in the MIR, must be an important consideration in reaching an understanding of the Universe at high redshift. Therefore we stress that the access of NGST to the thermal infrared would increase tremendously its scientific potential to study the early universe.
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We present imaging results and source counts from a deep ISOCAM cosmological survey at 15 microns, through gravitationally lensing galaxy clusters. We take advantage of the cluster gravitational amplification to increase the sensitivity of our survey. We detect a large number of luminous mid-IR sources behind the cluster lenses, down to very faint fluxes, which would have been unreachable without the gravitational lensing effect. These source counts, corrected for lensing distortion effects and incompleteness, are in excess of the predictions of no-evolution models that fit local IRAS counts. By integrating the 15 microns source counts from our counts limit, 30 microJy, to 50 mJy we estimate the resolved mid-IR background radiation intensity.
We present imaging results and source counts from an ISOCAM deep and ultra-deep cosmological survey through gravitationally lensing clusters of galaxies at 7 and 15 microns. A total area of about 53 sq.arcmin was covered in maps of three clusters. The lensing increases the sensitivity of the survey. A large number of luminous mid-infrared (MIR) sources were detected behind the lenses, and most could be unambiguously identified with visible counterparts. Thanks to the gravitational amplification, these results include the faintest MIR detections ever recorded, extending source counts to an unprecedented level. The source counts, corrected for cluster contamination and lensing distortion effects, show an excess by a factor of 10 with respect to the prediction of a no-evolution model, as we reported for A2390 alone in Altieri et al. (1999). These results support the A2390 result that the resolved 7 and 15 microns background radiation intensities are 1.7 (+/- 0.5) x 10^-9 and 3.3 (+/- 1.3) x 10^-9 W/m^2/sr, respectively, integrating from 30 microJy to 50 mJy.
We describe a mid-infrared (MIR) survey of local AGN to be conducted with the CanariCam instrument on the Gran Telescopio Canarias (GTC). We will obtain MIR imaging and spectroscopy of a sample of ~100 AGN covering six orders of magnitude in AGN luminosity, and including different AGN classes (e.g., LINERs, Seyfert 1s and 2s, QSO). The main goals are: (1) to test unification of Type 1 and Type 2 AGN, (2) to study the star formation activity around AGN, and (3) to explore the role of the dusty torus in low-luminosity AGN.
Supercontinuum (SC) generation based on ultrashort pulse compression constitutes one of the most promising technologies towards an ultra-wide bandwidth, high-brightness and spatially coherent light sources for applications such as spectroscopy and microscopy. Here, multi-octave SC generation in a gas-filled hollow-core antiresonant fiber (HC-ARF) is reported spanning from 200 nm in the deep ultraviolet (DUV) to 4000 nm in the mid-infrared (mid-IR). A measured average output power of 5 mW was obtained by pumping at the center wavelength of the first anti-resonance transmission window (2460 nm) with ~100 fs pulses and an injected pulse energy of ~7-8 {mu}J. The mechanism behind the extreme spectral broadening relies upon intense soliton-plasma nonlinear dynamics which leads to efficient soliton self-compression and phase-matched dispersive wave (DW) emission in the DUV region. The strongest DW is observed at 275 nm having an estimated pulse energy of 1.42 {mu}J, corresponding to 28.4 % of the total output energy. Furthermore, the effect of changing the pump pulse energy and gas pressure on the nonlinear dynamics and their direct impact on SC generation was investigated. The current work paves a new way towards novel investigations of gas-based ultrafast nonlinear optics in the emerging mid-IR spectral regime.
An unusual double-lobed extended X-ray source (RX J105343+5735) is detected in the ROSAT ultra-deep HRI image of the Lockman Hole. The angular size of the source is 1.7 X 0.7 arcmin^2 and its X-ray flux is 2 X 10^-14 erg cm^-2 s^-1. R-band imaging from the Keck telescope revealed a marginal excess of galaxies brighter than R=24.5, but Keck LRIS spectroscopy of 24 objects around the X-ray centroid did not yield a significant number of concordant redshifts. The brightest galaxy close to the centre of the eastern emission peak appears to be a gravitationally lensed arc at z=2.570, suggesting that the X-ray object is associated with the lens, most likely a cluster of galaxies. Based on a comparison of lensing surface mass density, X-ray luminosity, morphology and galaxy magnitudes with clusters of known distance, we argue that RX J105343+5735 is a cluster at a redshift around 1. Future X-ray, ground-based optical/NIR and high resolution HST observations of the system will be able to clarify the nature of the object.
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