| Proposal ID | 014874 |
| Title | X-ray weak broad-line quasars: absorption or intrinsic X-ray weakness |
| Download Data Associated to the proposal | https://nxsa.esac.esa.int/nxsa-sl/servlet/data-action-aio?obsno=0148740101 |
| DOI | https://doi.org/10.5270/esa-zrbak7m |
| Principal Investigator, PI | Mr Guido Risaliti |
| Abstract | We propose to observe a sample of 20 soft X-ray weak, optically red quasars,discovered by the Hamburg Quasar Survey. The lack of detection in the ROSATPSPC, despite their relatively bright optical emission make them a peculiarclass of quasars, classified as type 1 in the optical but type 2 in the X-rays.Establishing the X-ray properties of these objects is important for (1) theX-ray background synthesis models (they could be the missing QSO2s), (2) theunified models (they challenge the traditional torus model) and (3) the longdebated problem on the discrepancy between optical and X-ray luminosityfunctions. XMM provides the unique opportunity to observe a well defined sampleof such sources and measure their absorption column density in many cases. |
| Publications |
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| Instrument | EMOS1, EMOS2, EPN, OM, RGS1, RGS2 |
| Temporal Coverage | 2002-11-12T07:49:30Z/2003-12-19T00:32:29Z |
| Version | 17.56_20190403_1200 |
| Mission Description | The European Space Agencys (ESA) X-ray Multi-Mirror Mission (XMM-Newton) was launched by an Ariane 504 on December 10th 1999. XMM-Newton is ESAs second cornerstone of the Horizon 2000 Science Programme. It carries 3 high throughput X-ray telescopes with an unprecedented effective area, and an optical monitor, the first flown on a X-ray observatory. The large collecting area and ability to make long uninterrupted exposures provide highly sensitive observations. Since Earths atmosphere blocks out all X-rays, only a telescope in space can detect and study celestial X-ray sources. The XMM-Newton mission is helping scientists to solve a number of cosmic mysteries, ranging from the enigmatic black holes to the origins of the Universe itself. Observing time on XMM-Newton is being made available to the scientific community, applying for observational periods on a competitive basis. |
| Creator Contact | https://www.cosmos.esa.int/web/xmm-newton/xmm-newton-helpdesk |
| Date Published | 2005-01-20T00:00:00Z |
| Last Update | 2026-03-04 |
| Keywords | "ROSAT", "", "XMM", "absorption column density", "xray weakness", "optically red quasars", "qso2s "", "defined sample", "xray luminosity functions", "traditional torus model", "unified models", "hamburg quasar survey", "soft xray weak", "xray properties", "rosat pspc" |
| Publisher And Registrant | European Space Agency |
| Credit Guidelines | European Space Agency, Mr Guido Risaliti, 2005, 'X-ray weak broad-line quasars: absorption or intrinsic X-ray weakness', 17.56_20190403_1200, European Space Agency, https://doi.org/10.5270/esa-zrbak7m |