The variable X-ray spectrum of PDS456 and High-Velocity Outflows Shai Kaspi Technion – Haifa; Tel-Aviv University Israel & Ehud Behar, James Reeves “ The X-ray Universe 2008 ” – Granada, Spain – 29 May 2008 O’Brien P.T, Ward M., Braito V., Fabian A., Miller L., Mushotzky R., Turner T.J.

Outline - High-velocity mass outflows in AGNs - New data and first results of the varying spectrum of PDS Varying spectrum of PG Summary

Mass Outflow From AGNs Collimated jets and/or lobs in “ Radio loud ” quasars – 5%-10% of quasars are “ Radio loud ”. Broad absorption lines (BALs) – Blueshifted up to 0.1c - UV lines of ~10% “ radio quiet ” quasars. Does mass outflow from AGNs? Is mass loss an important component in most AGNs? Past decade UV (HST) and X-ray (XMM & Chandra) observations detected outflowing mass (velocities of several hundreds km/s) in the majority of moderate luminosity Seyfert galaxies (~70%), indicating the importance of mass outflow.

Mass outflow How much mass is carried out of the AGN by the outflow? How does it compared to the amount of matter being accreted? Does the ionized outflow carry a significant fraction of the energy output of the AGN? Answers are currently model dependent

Mass outflow in low-luminosity AGNs Outflows can provide key results about AGNs’ central regions, e.g.: Dynamics: outflows velocities of several 100 km/s in multiple components. Range of ionization parameters U Oxygen ~ 0.01 to 1 (degeneracy of location and density). Column density ~ cm -2. Normal outflows are not very significant in terms of energy as the outflow is of ~ M  yr -1. High-velocity mass outflows are potentially energetically significant.

High-Velocity Outflows L / L Edd UV BAL (km/s) N H [10 23 cm -2 ] V out [c]Source highY (12.4k) ~ 0.04c 1 ± , 0.4APM Chartas et al. (2002) 1.1N PG Pounds et al. (2003, 2006) 0.7Y (?)0.1 ± 0.05, , 0.34 PG Chartas et al. (2003, 2007) 0.3N PG Pounds et al. (2003) 1.0Y(?~12k)50.16PDS 456 Reeves et al. (2003) >0.5N IC 4329 A Markowitz et al. (2006) Mass outflow of several M  yr -1

PDS456 The most luminous radio-quiet type I quasar in the nearby Universe Discovered a decade ago (Torres 1997) Z=0.184 L Bol ~ erg/sec N H (Galactic)=2X10 21 cm -2

RXTE light curve Two main flux states: high and low

XMM observation 2001 Feb Ks Reeves, O'Brien, Ward (2003) EPIC spectra show soft excess and a deep absorption trough around 7 keV which if interpreted as Fe K-Shell absorption edges is an outflow at ~50000 km/sec. RGS spectra show deep absorption around 1 keV which if interpreted as a blend Fe L-shell absorption is an outflow at ~50000 km/sec.

Chandra/HETGS observation two years after the XMM one. PDS456 is in a low state and hardly any features can be detected. 40 ks 145 ks Chandra Observation 2003 May 7 – 145 ks

Two more XMM Observations Spectral variability over 1-2 days Behar et al. in prep.

EPIC-pn image

Problem with background in Background Source - Background Source + Background Background is showing strong narrow fluorescence emission lines due to K  of Al, Ni, Cu, and Zn from the CCD structure. Source+Background does not show these lines as the center of the CCD is free of these lines. Source-Background will indicate a false absorption line at ~8 keV.

.... No Problem with background of 2001 The background of the 2001 observation does not show the narrow emission lines. The deficit in flux around 8 keV is not caused by the background lines

XMM 2001 and 2007 comparison Strong variability over 6 years. Also spectral variability over 2 days. Behar et al. in prep.

RGS spectra Variability over 1-2 days – however features are not identified Behar et al. in prep.

L-shell absorption region 2007 observations do not show same absorption feature from 2001 Behar et al. in prep.

Suzaku – ks Fe absorption line Reeves et al. in prep. Black – Suzaku 2007 ; Red – XMM-Newton 2001 Fe XXVI 1s-2p 6.97 keV If the detected absorption is the Fe XXVI line then the outflows are at 0.26c and 0.31c

Spectra comparison from 2001 to 2007 Ratio of spectra to a  =2 power law illustrating the drastic long term spectral variability XMM 2001 Chandra 2003  =1.3 Suzaku 2007  =2.3

PG Pounds, Reeves et al. (2003) claim to detect an outflow of at ~ 0.1c. N H ~ cm -2 RGS O VIII O VII Fe XXVI S XVI EPIC-pn Kaspi & Behar (2006) gave alternative interpretation of an outflow at 3000 km/sec. N H ~ cm -2 Two interpretations – differ by two orders of magnitude in the outflowing mass

PG Two RGS observations Spectra are generally consistent, but a bit different slope and some different details. Object varied in time or a result of the poor S/N

Simultaneous XMM-Newton and Chandra Xmm-Newton/RGS and Chandra/LETGS spectra are consistent overall, but differ in many details – probably a consequence of the poor S/N.

Three Chandra/LETGS observations PG doubled its luminosity in two days. Narrow line features does not reproduce in the different spectra.

High-velocity outflows are not found in low-luminosity AGNs. Several High-luminosity AGNs have high-velocity outflows, indicating mass outflow that can affect the surrounding host galaxy. High-Velocity outflow are varying on time scales of days to years. The causes of the variability is yet to be determine: - Changes in the covering factor of the absorber. - Changes in the column density of the absorber. - The absorber is moving fast in and out of the line of sight. High-velocity mass outflow are potentially energetically significant but their variations and model dependent parameters cannot yet give a coherent picture. Summary – What can we learn… If High-velocity outflows are a transit phenomenon this needs to be taken into account when calculating the effect of the mass outflow on the surrounding.