X-ray emission from narrow-line Seyfert 1 galaxies with extreme narrow broad line width
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X-ray emission from narrow-line Seyfert 1 galaxies with extreme narrow broad line width Yanli Ai Yunnan Astronomical Observatory Weimin Yuan ( Yunnan Astronomical Observatory ) Stefanie komossa ( Max Planck Institute for Extraterrestrial Physics ). Narrow Line Seyfert 1 (NLS1).

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X-ray emission from narrow-line Seyfert 1 galaxies with extreme narrow broad line width

Yanli Ai

Yunnan Astronomical Observatory

Weimin Yuan (Yunnan Astronomical Observatory)

Stefanie komossa (Max Planck Institute for Extraterrestrial Physics)

Narrow line seyfert 1 nls1
Narrow Line Seyfert 1 (NLS1) extreme narrow broad line width

A special class of broad-line AGN

  • Some peculiar observed properties

  • softer X-ray spectra, rapid X-ray variability, strong optical FeII multiplets

  • Relatively small BH mass (e.g. Collin & Kawaguchi ’04)

    Accreting close to the Eddington rate L/LEdd~1 possible via slim disk, c.f. standard disk

    (e.g. Abramowicz + ‘88; Wang J.-M. + ‘99, Mineshige + ’00)

Balmer lines broader than forbidden lines (observable BLR) but narrower than normal type I AGN (fwhm < 2000km/s)


Zhou et al. 2006 selected ~ 2000 NLS1s from SDSS extreme narrow broad line width

Break down at ~ 1000 km/s

Motivation :

Γ - FWHM (Hβ) anti-correlation

important in AGN correlation space (Eigenvector 1 )

ROSAT photon index

X-ray properties of these NSL1s with extreme narrow Balmer line width is interesting !

Soft X-ray excess emission

NLS1s + Sy1s

Zhou et al . 2006

Estimated from hardness ratio

Uncertainty :

spectral model assumption

intrinsic absorption

Boller et al .1996

Detailed X-ray analysis needed !

Soft x ray excess emission sxe
Soft X-ray excess emission extreme narrow broad line width (SXE)

Steeper Soft X-ray spectrum is caused by stronger soft excess emissionobserved kT > maximum standard accretion disk KT Cannot be explained by the thermal emission from the standard accretion diskquestion: where does SXE come from?

Crummy et al. 2006

Viable models of sxe
Viable models of SXE extreme narrow broad line width

from Done + 2007


kT~0.1-0.2keV tau~20

reflection (scattering)

Ionized disk

Absorption by

optically thin gas

Czerny & Elvis ‘87, Wandel & Petrosian ‘88, Shimura & Takahara ‘95

Ross & Fabian’05,

Crummy + ’06

Done + et al. ‘06

Atomic opacity in E~0.7-3keV

OVII/VIII, Fe L-shell absorption edges

Sample selection extreme narrow broad line width1) FWHM (Hβ) < 1200km/s from 2,000 NLS1s in Zhou et al (2006)2) matched with ROSAT PSPC and 2XMM with radius of 30" and 5" respectively.3) requiring X-ray counts > 200 for spectral analysisconsist of 20 NLS1s, having 12 observations in XMM and 13 in ROSATProperties :1) typical NLS1s in optical 2) small balck hole masses (three IMBH candidates in Greene & Ho, 2004)3) high Eddington ratio4) all are radio-quiet except SDSS J1633+4718 with radio loudness of 2.13

In 0.2-10.0 KeV eight NLS1s have enough photons for X-ray spectral analysis soft excess exist for all of them

Result of soft X-ray spectral fitting spectral analysis strong intrinsic absorption have not been detectedOur result confirm the break down of Γ - FWHM(Hβ) relation in Zhou et al. (2006)

Soft excess temperature distribution spectral analysis 1) higher than expected maximum standard accretion disc temperature2) in 100 - 200 eV, similar to that in much more massive PG quasar

Soft X-ray excess strength distribution spectral analysis soft excess strength does not increase with decrease of line width .possible explanation for break down : soft excess saturates at FWHM around 1000 km/s

Summary of soft x ray excess spectral fitting
Summary of soft X-ray excess spectral fitting spectral analysis

  • Soft X-ray excess is almost ubiquitous and prominent

  • Additional emission component models

    • blackbody or BB (always fit but NOT necessarily the best)

    • Comptonization

  • Disk reflection

    • required for several other objects

    • dominate direct emission, large reflection fraction>>1

  • absorption

    • no good fit, also by variability

  • Sometimes a partially ionized thin absorber is required

    (but not strong enough, not blurred)

either an additional emission component or disk reflection dominated

Example: SDSS J0940+0324 spectral analysis

Compton scattering



0.34 KeV Γ=1.99 chi^2 = 274.4 (273dof)

Example: SDSS J2299+0107 spectral analysis

Blurred disk refl.

Power-law + BB



R_in=2.2Rg extreme !

chi^2=278(290 d.o.f)

kT=0.13KeV Γ=2.7

chi^2 = 293 (293 d.o.f.)

Summary spectral analysis

1). In spectral analysis of 20 NSL1s we confirmed our result in Zhou et al. (2006) that soft X-ray photon indices and the broad optical emission line widths break down at FWHM (Hβ) around 1000km/s. saturation of the relative strength of soft excesss at narrow line width as one possible explanation.

2). thermal temperature of excess in 100 - 200eV, quite same with much more massive radio-quiet QSOs. Significantly higher than the maximum accretion disk temperature

3). SXE may have different origins.

Comptonization can reproduce soft excess feature in five NLS1s with relatively low Eddington ratio ( < 0.5);

blurred ionized disc reflection model well reproduce the XMM spectra in three NLS1s with high Edd. ratio. Our result suggest the origin may be dependent on Edd. Ratio ( ~ 1.0 )

Thank you spectral analysis