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X-ray He-like ion diagnostics for photoionized plasma Application to the NGC 1068 galaxy. Olivier Godet (CESR, France). Collaborators : Suzy Collin & Anne-Marie Dumont (Observatoire de Paris-Meudon, France). Summary. Olivier Godet Journées de la sf2a 2004.

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Presentation Transcript
slide1

X-ray He-like ion diagnostics

for photoionized plasma

Application to the NGC 1068 galaxy

Olivier Godet

(CESR, France)

Collaborators : Suzy Collin & Anne-Marie Dumont

(Observatoire de Paris-Meudon, France)

slide2

Summary

Olivier Godet Journées de la sf2a 2004

  • Introduction to Active Galaxy Nuclei
  • Titan: a photoionization code
  • X-ray diagnostics for photoionized plasma

in AGN

  • Application to the NGC 1068 galaxy
slide3

Different angles on a galaxy with jets

Different angles on a galaxy with jets

Zooming in on a galaxy with jets

Zooming in on a galaxy with jets

AGN: a galaxy in which a tremendous

energy is emitted from the nucleus

AGN: a galaxy in which a tremendous

energy is emitted from the nucleus

down the jet

down the jet

Viewing

Viewing

Blazar / Seyfert 1

Blazar / Seyfert 1

Accretion disk

Quasar

Quasar

Viewing at an

angle to the jet

Viewing at an

angle to the jet

Torus

QSO 2 / Seyfert 2

QSO 2 / Seyfert 2

Black hole

Viewing at 90°

Viewing at 90°

Unification Scheme (Antonucci 1993)

from the jet

from the jet

Olivier Godet Journées de la sf2a 2004

slide4

X-ray Source

Reflected spectrum

Incident continuum (FX)

Medium (10 most abundant elements)

Transmitted spectrum

The line fluxes are computed an accuracy within 4%

Titan: a photoionization code

Titan :Code for the modelling of the X-ray spectrum in AGN

and X-ray binaries

Titan computes a full radiative transfert for the continuum and

the lines in solving the ionization and thermal equilibria through

the medium (ALI method).

Olivier Godet Journées de la sf2a 2004

slide5

Flux (10-4 ph cm-2 s-1 Å-1)

Soft X-ray spectrum of the NGC 1068 galaxy observed by XMM-Newton

λ (Å)

Olivier Godet Journées de la sf2a 2004

A new X-ray vision of the Universe

XMM-Newton and Chandra : a new X-ray vision with the

high resolution spectroscopy

Many emission lines are resolved in AGN and X-ray binaries

slide6

Measurable quantities to probe the emitting media

Tools to constrain the geometrical and physical parameters

Coupé, Godet, Dumont, Collin A&A 2004

Godet, Collin, Dumont A&A submitted

Olivier Godet Journées de la sf2a 2004

A new X-ray vision of the Universe

XMM-Newton and Chandra : a new X-ray vision with the

high resolution spectroscopy

Many emission lines are resolved in AGN and X-ray binaries

Study of the properties of spectral characteristics in photoionized

media met in AGN with a grid of models computed by Titan

slide7

Tmax (K)

e-

1000

continuum

300

100

30

10

Te

ground level

CDOVII(cm-2)

5

A ‘universal’ plot

From the electronic temperature of the RRC, the ionization

parameter ξ could be derived.

Olivier Godet Journées de la sf2a 2004

X-ray diagnostics for photoionized plasmas

Radiative Recombination Continuum

(ξ corresponds to the ionization state of the emitting medium)

slide8

f + i

G=

r

G(OVII)

10

5

1000

30

100

300

CD (cm-2)

Degeneracy in the CD solutions

Olivier Godet Journées de la sf2a 2004

X-ray diagnostics for photoionized plasmas

Study of the He-like triplet lines:

resonance (r); intercombination (i); forbidden (f)

G increases with CD, because the

line r deacreases due to a decrease

of the incident radiative excitation.

Results without a turbulent velocity Vd

slide9

X-ray Chandra image

Olivier Godet Journées de la sf2a 2004

Application to the NGC 1068 galaxy (1)

NGC 1068: a nearby Seyfert 2 galaxy

(starburst) at 14.4 Mpc (Blandford et al. 1997)

and L ~ 1011 L

Spectral analysis of the archive data of NGC 1068 observed

by XMM-Newton on 2000 July 29

- Reflexion Grating Spectrometer

- EPIC-pn

slide10

Tmax (K)

ξ ~ 10

Te ~ 4.5 x 104 K

CDOVII(cm-2)

Olivier Godet Journées de la sf2a 2004

Application of the NGC 1068 galaxy (2)

A similar result is found from the NVII and NVI (ξ ~ 5-10)

slide11

ξ known supression of degeneracy

G(OVII)

CD (cm-2)

G(FeXXV)

ξ=10

ξ=1000

ξ=1000

ξ=300

From G(NVI) and ξ=5-10,

CD ~ 2-4 x 1020 cm-2

CD (cm-2)

~1020

~1022

Application to the NGC 1068 galaxy (3)

Media without a turbulent velocity Vd

Olivier Godet Journées de la sf2a 2004

slide12

Line blueshifted velocities:

Vshift (FeXXV) ~ 1000-1700 km/s

Vshift (OVII) ~ 200-400 km/s

Two emitting regions

With a turbulent velocity Vd=300 km s-1

The CD-values are larger by a factor 10

for the same ξ-value (CD~1.0-4.0 x 1021 cm-2)

CDOVII ~ 0.6-1.0 x 1018 cm-2

Application to the NGC 1068 galaxy (4)

And the derived CD- and ξ-values

Olivier Godet Journées de la sf2a 2004

slide13

Conclusion

  • From the He-like triplet lines and Vd=300km s-1,
  • the X-ray spectrum is emitted by 2 regions:
  • - one with CD~1023 cm-2 and ξ~1000
  • - one with CD~1.0-4.0 x 1021 cm-2 and ξ~5-10
  • The ion CDs are consistent with those found in
  • Seyfert 1 galaxies (Kaspi et al. 2000; Sako et al. 2001)
  • CDOVII ~ 3.0-7.0 x 1017 cm-2

Olivier Godet Journées de la sf2a 2004

slide14

Future works

  • Refined model to be derived with our grid of models
  • Comparison of the results from NGC 1068 with other
  • Seyfert 2 observations
  • Study of the H-like over the He-like line ratios

Olivier Godet Journées de la sf2a 2004