We construct the first X-ray selected sample of broad line radio-loud AGN from the EMSS survey. In order to test unifying schemes for radio-loud objects, their spectral and statistical properties (both at and steep spectrum objects) are examined and compared with those of other samples of blazars. The X-ray selection allows us to explore properties of radio-loud quasars 10-100 weaker in the radio band than classical samples. The most convincing interpretation of our results is that there are no radio-loud quasars whose synchrotron emission peak reaches the EUV-soft X-ray band at these (radio) flux levels. Moreover, due to the comparatively weak non-thermal emission, a quasi-thermal component appears to contribute at optical-UV energies. The detection of sources at low radio fluxes also reveals a large population of steep spectrum quasars and the lack of the predicted turnover in the quasar (radio) counts. The evolution of X-ray selected radio-loud quasars does not significantly differ from that of radio-selected ones, and at spectrum and steep spectrum sources appear to behave quite similarly. Keywords
An X-ray selected sample of radio-loud quasars / Wolter, A.; Celotti, Anna Lisa. - In: ASTRONOMY & ASTROPHYSICS. - ISSN 0004-6361. - 371:2(2001), pp. 527-537. [10.1051/0004-6361:20010415]
An X-ray selected sample of radio-loud quasars
Celotti, Anna Lisa
2001-01-01
Abstract
We construct the first X-ray selected sample of broad line radio-loud AGN from the EMSS survey. In order to test unifying schemes for radio-loud objects, their spectral and statistical properties (both at and steep spectrum objects) are examined and compared with those of other samples of blazars. The X-ray selection allows us to explore properties of radio-loud quasars 10-100 weaker in the radio band than classical samples. The most convincing interpretation of our results is that there are no radio-loud quasars whose synchrotron emission peak reaches the EUV-soft X-ray band at these (radio) flux levels. Moreover, due to the comparatively weak non-thermal emission, a quasi-thermal component appears to contribute at optical-UV energies. The detection of sources at low radio fluxes also reveals a large population of steep spectrum quasars and the lack of the predicted turnover in the quasar (radio) counts. The evolution of X-ray selected radio-loud quasars does not significantly differ from that of radio-selected ones, and at spectrum and steep spectrum sources appear to behave quite similarly. KeywordsI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.