perhaps the most important finding from the iras survey was the discovery of a significant population of galaxies whose infrared luminosities are equivalent to the bolometric luminosities of optically-selected quasars. assessing the relative importance of an agn and massive stars for powering ultraluminous ir galaxies (uligs) is essential for understanding these objects as massive galaxies and/or quasars in formation, and for testing suggestions of an evolutionary connection between starburst and agn phenomena. the target galaxies were taken from a recently compiled sample of uligs which contains the brightest objects at a given l_ir (< 10^13 l_sun) and which is not biased towards warm. quasar-like objects with large s(25 um)/s(60 um) ratios. the galaxies in our sample span the luminosity range logl_ir/l_sun = 12.3 - 13, currently not explored spectroscopically by the iso central program. the central programme focuses on previously published objects that typically lie below this range of l_ir, and the few exotic hyperluminous. (l_ir > 10^13 l_sun) objects at much higher redshifts. our sample therefore provides an important bridge between these two extremes that could prove critical to the interpretation of the more distant hyperluminous. objects. we plan to measure the fluxes of the fine-structure lines ne ii 12.8 um, ne iii 15.6 um, ne iii 36.0 um, ne v 14.3 um, o iii 52 um, and o iii 88 um. these data will then be combined with our optical and near-infrared measurements to (1) determine the physical conditions and ionization mechanisms of the nebular gas in these galaxies, (2) measure the stellar content in the objects powered by stars, and (3) evaluate the importance of dust extinction. this study will provide new insights into the relative role of starbursts and agn in powering uligs, and possible evolutionary links between these two phenomona.
Instrument
SWS02
Temporal Coverage
1996-07-15T10:55:03Z/1997-01-07T16:59:19Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the worlds first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
European Space Agency, SANDERS et al., 1999, 'INFRARED SPECTROSCOPY OF A UNBIASED SAMPLE OF ULTRALUMINOUS IRAS GALAXIES WITH LOGSQUARE_BRACKET_OPENL_IR\/L_SUNSQUARE_BRACKET_CLOSE = 12.3 - 13.0 AND Z = 0.1 - 0.3.', 1.0, European Space Agency, https://doi.org/10.5270/esa-b6ie9bp
