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The variable X-ray spectrum of PDS456 and High-Velocity Outflows

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

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The variable X-ray spectrum of PDS456 and High-Velocity Outflows

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

  2. Outline • High-velocity mass outflows in AGNs- New data and first results of the varying spectrum of PDS 456- Varying spectrum of PG 1211+143- Summary

  3. Mass Outflow From AGNs Does 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. 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.

  4. 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

  5. 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 UOxygen ~ 0.01 to 1 • (degeneracy of location and density). • Column density ~ 1021-23 cm-2. • Normal outflows are not very significant in terms • of energy as the outflow is of ~ 0.1-5 M yr-1. High-velocity mass outflows are potentially energetically significant.

  6. High-Velocity Outflows Mass outflow of several M yr-1

  7. The most luminous radio-quiet type I quasar in the nearby Universe Discovered a decade ago (Torres 1997) Z=0.184 LBol ~ 1047 erg/sec NH(Galactic)=2X1021 cm-2 PDS456

  8. RXTE light curve Two main flux states: high and low

  9. 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. XMM observation 2001 Feb 26 - 40Ks 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.

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

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

  12. EPIC-pn image - 2007

  13. Background is showing strong narrow fluorescence emission lines due to Ka of Al, Ni, Cu, and Zn from the CCD structure. . Background Source+Background does not show these lines as the center of the CCD is free of these lines. Source + Background Problem with background in 2007 Source - Background Source-Background will indicate a false absorption line at ~8 keV.

  14. . . 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 No Problem with background of 2001

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

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

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

  18. Black – Suzaku 2007 ; Red – XMM-Newton 2001 Suzaku – 2007-2-24 - 370 ks Fe absorption line Fe XXVI 1s-2p 6.97 keV Reeves et al. in prep. If the detected absorption is the Fe XXVI line then the outflows are at 0.26c and 0.31c

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

  20. EPIC-pn S XVI Fe XXVI RGS O VII O VIII O VIII Pounds, Reeves et al. (2003) claim to detect an outflow of at ~ 0.1c. NH ~ 1024 cm-2 PG1211+143 Kaspi & Behar (2006) gave alternative interpretation of an outflow at 3000 km/sec. NH ~ 1021.5 cm-2 Two interpretations – differ by two orders of magnitude in the outflowing mass

  21. Object varied in time or a result of the poor S/N PG1211+143 Two RGS observations 2001-06-15 2004-06-21 Spectra are generallyconsistent, but a bit different slope and some different details.

  22. 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.

  23. Three Chandra/LETGS observations PG 1211+143 doubled its luminosity in two days. Narrow line features does not reproduce in the different spectra.

  24. Summary – What can we learn… • 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. • 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.

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