THE X-RAY PROPERTIES OF TYPICAL HIGH-REDSHIFT RADIO-LOUD QUASARS Accepted in ApJ (arXiv:1106.2557) Cristian Saez (PSU) Niel Brandt (PSU) Ohad Shemmer (UNT) Laura Chomiuk(CfA) Laura Lopez (UCSC) Herman Marshall (MIT) Brendan Miller (UMich) Cristian Vignali (INAF)

Highlights of our Study In a sample of typical high-redshift (z >~ 4) RLQs: Study the X-ray spectral properties: 4 XMM and 2 Chandra (~50 ks) moderate to high quality observations (total number counts per observation between 100-4000 cnts). These sources were already observed before with short exposure (~5ks) Chandra observations (Bassett et al. 2004; Lopez et al. 2006; Shemmer et al. 2006). Seek for evidence of Jets: Two sources (PMN J0235-1805 and PMN J2219-2719) with Chandra and VLA observations (“Snapshot Candidates”; Lopez et al. 2006). Compare spectral properties of high redshift RLQs with those of lower redshift RLQs.

What are we studying? Does the radio loudness of the RLQs comes from synchrotron radiation? Multicolour SDSS optical images of NGC5806 (z=0.0045 ).

Our Sample Highlights of our sample: High redshift. Good quality X-ray spectra. Moderate Radio loudness. Talk about distribution of RLQs, The dotted curve along the left side of the plot shows the relative number of RLQs versus RL from Ivezic et al. (2002).

PART I Spectral Analysis Now we are going to go more in depth with our first goal.

Spectral Analysis Results No sign of reflection in our sources. <Γ>=1.74 ± 0.11; in accordance to median values of lower redshift RLQ samples (e.g, Reeves & Turner 2000). Evidence of absorption in one source (NH ~ 2×1022 cm-2). Long term Flux variability in 2 of our sources (PMN J02140-518 and PMN J2219-2719; time scales ~500 days).

Absorption in SDSS J0011+1446 Contour plots 68%, 90% and 99%.

PART II The quest of Jets

Evidence of a weak jet in PMN J2219-2719 (1) Radio emission at 4.9 GHz. Over-density significant ~ 4σ

Evidence of a weak jet in PMN J2219-2719 (2) Two of the most popular models for this kpc-scale emission (e.g., Worrall 2009, and references therein) are (1) an extra high-energy synchrotron component, and (2) inverse Compton (IC) scattering by relativistic electrons of photons of the cosmic microwave background (CMB; or the IC/CMB model). For synchrotron models, we do not obviously expect that the X-ray emission properties would depend on redshift. The energy density of the CMB increases as (1 + z)^4; as a consequence, an implication of the IC/CMB model is that for high-redshift RLQs (z > 4) the X-ray emission from extended jets may outshine that from the core (e.g., Schwartz 2002). X-ray flux jet ~ 2% X-ray flux core

PART III Seeking for relations and comparing our sample with lower redshift samples

Gamma vs RL Anticorrelation between Γ and RL. Significant at the 99.9% confidence level. Similar dependency is found in lower redshift sources (e.g., Reeves & Turner 2000). The hardening of the spectra with RL suggest rising jet contribution to the X-ray spectra as a function of RL. Expanded sample with z > 2 RLQs.

Γ-RL relation for low and high redshift sources. Γ = α + β × log RL To estimate α and β using the IDL routine from Kelly 2007. --- Our ex. sample (z > 2) … Reeves & Turner 2000 (z < 2) Why a Bayesian approach is necessary??? We adopt the IDL Astronomy Library tool linmix err (Kelly 2007) to estimate the parameters describing a linear model between Gamma and log RL. This IDL routine, which accounts for measurement errors and intrinsic scatter, is implemented with a Bayesian approach to compute the posterior probability distribution from the observed data. (68% and 99% contour plots). Kelly (2007)

Conclusions The power-law X-ray continua of our targets is consistent with measurements of lower redshift RLQs. Anti-correlation between photon index and radio loudness that is consistent with what has been observed at lower redshifts. SDSS J0011+1446 has significant X-ray absorption with a column density NH ~ 2×1022 cm-2 Likely X-ray jet in the Chandra observation of PMN J2219-2719.