K. Leech

An ISOCAM survey through gravitationally lensing galaxy clusters - I. Source lists and source counts for A370, A2218 and A2390

PCT No. PCT/DE89/00650 Sec. 371 Date Mar. 6, 1991 Sec. 102(e) Date Mar. 6, 1991 PCT Filed Oct. 12, 1989 PCT Pub. No. WO90/04702 PCT Pub. Date May 3, 1990.A partial flue gas stream is used for the production of electrical energy and/or heating and operational heat by utilizing combustion heat from fossil fuels, prior to combustion dried in an indirectly heated fluidized bed dryer, with combustion flue gas used as a carrier medium for the fluidized bed dryer. The mixture of flue gases and steam, deriving from the drying process, is after an intermediate treatment, if necessary, discharged with the main flue gas stream.

An ISOCAM survey through gravitationally lensing galaxy clusters - II. The properties of infrared galaxies in the A2218 field

We have observed the cluster Abell 2218 (z = 0.175) with ISOCAM on board the Infrared Space Observatory using two filters, LW2 and LW3, with reference wavelengths of 6.7 and 14.3 μm, respectively. We detected 76 sources down to 54 and 121 μJy (50% completeness levels) at 6.7 and 14.3 μm, respectively. All these sources have visible optical counterparts. We have gathered optical and near-infrared magnitudes for 60 of the 67 non-stellar optical counterparts to the ISOCAM sources, as well as redshifts for 43 of them. We have obtained acceptable and well constrained fits to the observed spectral energy distributions (SEDs) of 41 of these sources, using the GRASIL models of Silva et al. (1998), and have determined their total infrared luminosities (L IR s) and star formation rates (SFRs). The SEDs of 20 (out of 27) ISOCAM cluster members are best fit by models with negligible ongoing star formation, and no major episode of star formation in the last 1 Gyr. Their SEDs resemble those of 5-10 Gyr old early-type galaxies. A slightly higher, but still very mild, star-formation activity is found among the remaining cluster sources, which are mostly spirals. The median IR luminosity of the 27 ISOCAM cluster sources is L IR = 6 x 10 8 L ○. . The ISOCAM-selected cluster galaxies have indistinguishable velocity and spatial distributions from those of the other cluster galaxies, and do not contribute significantly to the Butcher-Oemler effect. If A2218 is undergoing a merger, as suggested by some optical and X-ray analyses, then this merger does not seem to affect the mid-infrared properties of its galaxies. The SEDs of most ISOCAM-selected field sources are best fit by models with moderate ongoing star formation, with a significant fraction of their stellar mass formed in the last ∼1 Gyr. Their SEDs resemble those of massive star-forming spirals or starburst galaxies, observed close to the maximum of their star formation activity, but not necessarily during the short-lived starburst event. The median redshift of these field galaxies is z ≃ 0.6. Their L IR s span almost two orders of magnitudes, from ∼10 10 L ○. to 10 12 L ○. , with a median of 1.2 x 10 11 (eight of the 14 field sources are LIRGs). The SFRs of these 14 ISOCAM-selected field sources range from 2 to 125 M ○. yr -1 , with a median value of 22 M ○. yr -1 . We compare our findings with those obtained in other ISOCAM cluster and field surveys.

ISO observations of the interacting galaxy Markarian 297 with the powerful supernova remnant 1982aa

Markarian (Mkn) 297 is a complex system comprised of two interacting galaxies that has been modelled with a variety of scenarios. Observations of this system were made with the Infrared Space Observatory (ISO) using the ISOCAM, ISOPHOT and LWS instruments. ISOCAM maps at 6.7 µm, 7.7 µm, 12 µm and 14.3 µm are presented which, together with PHT-S spectrometry of the central interacting region, probe the dust obscured star formation and the properties of the organic dust. The ISOCAM observations reveal that the strongest emission in the four bands is at a location completely unremarkable at visible and near-IR (e.g. 2MASS) wavelengths, and does not coincide with the nuclear region of either colliding galaxy. This striking characteristic has also been observed in the overlap region of the colliding galaxies in the Antennae (NGC 4038/4039), the intragroup region of Stephan’s Quintet, and in IC 694 in the interacting system Arp 299, and again underlines the importance of infrared observations in understanding star formation in colliding/merging systems. At 15 µm, the hidden source in Mkn 297 is, respectively, 14.6 and 3.8 times more luminous than the hidden sources in the Antennae (NGC 4038/4039) and Stephan’s Quintet. Numerical simulations of the Mkn 297 system indicate that a co-planar radial penetration between two disk galaxies yielded the observed wing formation in the system about 1.5 × 10 8 years after the collision. A complex emission pattern with knots and ridges of emission was detected with ISOCAM. The 7.7 µm map predominantly shows the galaxy in emission from the 7.7 µm feature attributed to PAHs (Polycyclic Aromatic Hydrocarbons). The 14.3/7.7 µm ratio is greater than unity over most of the galaxy, implying widespread strong star formation. Strong emission features were detected in the ISOPHOT spectrum, while [O I], [O III] and [C II] emission lines were seen with LWS. Using data from the three instruments, luminosities and masses for two dust components were determined. The total infrared luminosity is approximately 10 11 L� ,w hich (marginally) classifies the system as a luminous infrared galaxy (LIRG). A supernova that exploded in 1979 (SN 1982aa) gave rise to one of the most powerful known radio remnants which falls close to the strongest mid-infrared source and is identified with star forming region 14 in the optical. This supernova explosion may have been accompanied by a gamma-ray burst (GRB), consistent with the idea that GRBs are associated with supernovae in star forming regions, and a search for a GRB consistent with the direction to Mkn 297, in satellite data from July to December 1979, is recommended.