%0 Generic %1 ghisellini2015quenching %A Ghisellini, G. %A Haardt, F. %A Ciardi, B. %A Sbarrato, T. %A Gallo, E. %A Tavecchio, F. %A Celotti, A. %D 2015 %K blazar cmb radio %T CMB quenching of high-redshift radio-loud AGNs %U http://arxiv.org/abs/1505.05512 %X The very existence of a dozen of high-redshift (z>4) blazars indicates that a much larger population of misaligned powerful jetted AGN was already in place when the Universe was <1.5 Gyr old. Such parent population proved to be very elusive, and escaped direct detection in radio surveys so far. High redshift blazars themselves seem to be failing in producing extended radio-lobes, raising questions about the connection between such class and the vaster population of radio-galaxies. We show that the interaction of the jet electrons with the intense cosmic microwave background (CMB) radiation explains the lack of extended radio emission in high redshift blazars and in their parent population, possibly accounting for the apparently missing misaligned counterparts of high redshift blazars. We then model the spectral energy distribution of blazar lobes following simple prescriptions, finding that most of them should be detectable by low frequency deep radio observations, e.g., by LOw-Frequency ARray for radio astronomy (LOFAR) and by relatively deep X-ray observations with good angular resolution, e.g., by the Chandra satellite. We finally show that when misaligned, the jet emission is faint (de-beamed) and missed by current large sky area surveys. Since the isotropic lobe radio emission is also quenched by the CMB cooling, sources with even very powerful jets can go undetected in current radio surveys, and misclassified as radio-quiet AGNs.

@misc{ghisellini2015quenching, abstract = {The very existence of a dozen of high-redshift (z>4) blazars indicates that a much larger population of misaligned powerful jetted AGN was already in place when the Universe was <1.5 Gyr old. Such parent population proved to be very elusive, and escaped direct detection in radio surveys so far. High redshift blazars themselves seem to be failing in producing extended radio-lobes, raising questions about the connection between such class and the vaster population of radio-galaxies. We show that the interaction of the jet electrons with the intense cosmic microwave background (CMB) radiation explains the lack of extended radio emission in high redshift blazars and in their parent population, possibly accounting for the apparently missing misaligned counterparts of high redshift blazars. We then model the spectral energy distribution of blazar lobes following simple prescriptions, finding that most of them should be detectable by low frequency deep radio observations, e.g., by LOw-Frequency ARray for radio astronomy (LOFAR) and by relatively deep X-ray observations with good angular resolution, e.g., by the Chandra satellite. We finally show that when misaligned, the jet emission is faint (de-beamed) and missed by current large sky area surveys. Since the isotropic lobe radio emission is also quenched by the CMB cooling, sources with even very powerful jets can go undetected in current radio surveys, and misclassified as radio-quiet AGNs.}, added-at = {2015-05-22T09:43:53.000+0200}, author = {Ghisellini, G. and Haardt, F. and Ciardi, B. and Sbarrato, T. and Gallo, E. and Tavecchio, F. and Celotti, A.}, biburl = {https://www.bibsonomy.org/bibtex/2928b753cbed521b6353071368f940d70/miki}, description = {[1505.05512] CMB quenching of high-redshift radio-loud AGNs}, interhash = {a023eff239a23a806d9549c5decdf0e8}, intrahash = {928b753cbed521b6353071368f940d70}, keywords = {blazar cmb radio}, note = {cite arxiv:1505.05512Comment: 10 pages, 6 figures, submitted to MNRAS}, timestamp = {2015-05-22T09:43:53.000+0200}, title = {CMB quenching of high-redshift radio-loud AGNs}, url = {http://arxiv.org/abs/1505.05512}, year = 2015 }