Two Candidate High-redshift X-Ray Jets without Coincident Radio Jets

D A Schwartz,J F C Wardle,A Siemiginowska,H Marshall,B Snios,C C Cheung,D M Worrall,M Birkinshaw,Doug Gobeille,G Migliori

doi:10.3847/1538-4357/abbd99

Abstract

Abstract We report the detection of extended X-ray emission from two high-redshift radio quasars. These quasars, J1405+0415 at z = 3.208 and J1610+1811 at z = 3.118, were observed in a Chandra snapshot survey selected from a complete sample of the radio-brightest quasars in the overlap area of the VLA-FIRST radio survey and the Sloan Digital Sky Survey. The extended X-ray emission is located along the line connecting the core to a radio knot or hotspot, favoring the interpretation of X-ray jets. The inferred rest-frame jet X-ray luminosities from 2 to 30 keV would be of order 1045 erg s−1 if emitted isotropically and without relativistic beaming. In the scenario of inverse Compton scattering of the cosmic microwave background (CMB), X-ray jets without a coincident radio counterpart may be common, and should be readily detectable to redshifts even beyond 3.2 due to the (1+z)4 increase of the CMB energy density compensating for the (1+z)−4 cosmological diminution of surface brightness. If these can be X-ray confirmed, they would be the second and third examples of quasar X-ray jets without detection of underlying continuous radio jets.

Highlights

The first jet from an active galactic nuclei was discovered as a visible image in a photograph of M87 (Curtis 1918), they have been observed primarily as radio phenomena (e.g., Turland 1975; Waggett et al 1977; Readhead et al 1978; Perley et al 1979; Bridle & Perley 1984)
Jets provide a mechanism to explain the morphologies of extragalactic radio sources and to supply the large energy content inferred in lobes of extragalactic radio sources (e.g., Rees 1971; Longair et al 1973; Blandford & Rees 1974; Scheuer 1974)
Using a model-dependent assumption that the X-rays are generated by inverse Compton (IC) up-scattering of the cosmic microwave background (CMB) radiation (Tavecchio et al 2000; Celotti et al 2001), X-rays help estimate the enthalpy flux, often called “power,” that

Summary

Introduction

The first jet from an active galactic nuclei was discovered as a visible image in a photograph of M87 (Curtis 1918), they have been observed primarily as radio phenomena (e.g., Turland 1975; Waggett et al 1977; Readhead et al 1978; Perley et al 1979; Bridle & Perley 1984). The power carried by kiloparsec-scale jets has generally been estimated by assessment of the energy deposited into radio lobes and cocoons (Scheuer 1974; Rawlings & Saunders 1991; Willott et al 1999), or by the energy required to create cavities observed in the hot intracluster or intragalactic gas at low redshift (Birzan et al 2008), or by empirical scaling relations derived from those methods (e.g., O’Dea et al 2009; Cavagnolo et al 2010; Daly et al 2012). Photon number indices are α + 1, and corresponding relativistic electron number spectra are dN dg μ g-(2a+1), where γ is the electron Lorentz factor

The High-redshift Sample

Extended X-Ray Emission

Findings

The X-Ray Dominated Jets