1

X-ray Diagnostics of Physical Conditions in Warm Absorbers

Y. Krongold (UNAM)

N. Brickhouse (CfA)M. Elvis (CfA)

F. Nicastro (CfA)S. Mathur (Ohio State U.)

D. Liedahl (LLNL)

2

Found in the X-ray and UV spectra of 1/2 of all Seyfert 1 galaxies

Blueshifted (500-1000 km s-1) winds

mOUT maccr dynamically important

Valuable to understand quasars Interaction with ISM Metal pollution of the IGM

Warm Absorbers

3

NGC 3783 Bright Seyfert galaxy redshift 0.0097

(2926 km s-1)

Extensively observed in the X-rays Monitored by the Chandra HETGS, Total exposure of 900 ksec > 2000 counts per resolution element at

7 A

4

NGC 3783 Chandra MEG 900 ksec exposure

1keV

5

Modeling with PHASE

Based on APED (Smith et al. 2001) accuracy in the wavelength

Plus data for inner shell transitions (Behar et al. 2001, 2002), and from Verner list

Ionization balance from CLOUDY Includes a Voigt Profiles Self Consistent Model Global Fit

6

NGC 3783 Model

Photoionization Equilibrium Models

3 Free parameters per absorption component:

U =Q/4cr2n Ionization Parameter NH Column Density VOUT Outflow Velocity

2 Absorption Components

7

NGC 3783 Chandra MEG 900 ksec exposure

1keV

8

NGC 3783 Chandra MEG 900 ksec exposure

9

Model Highlights

Simple solution only 2 absorbing components (LIP and HIP)

Fits more than 100 features with only 6 free parameters.

Predicts reasonable absorption in the UV by the LIP

Netzer et al. (2003) modeled a third hotter component (Fe K-shell, VHIP)

10

Does not fit two significant LIP lines:

Si X, Si XI

Lack of low temperature (n=0) DR rates for Fe M-shell (Netzer et al. 2003; Netzer 2004; Kraemer Ferland and Gabel 2004)

Si X-XISi X-XI

11

Other Representation Many Charge states present in the spectrum

Continuous Radial Flow of Ionization structures

Several charge states of the same element are significantly present

Not a global fit, but based on ion by ion Fits everything 40 free parameters Not self consistent

12

Pressure Equilibrium

Similar kinematical properties

Confirmed by Netzer et al. (2003), plus 3erd component

3 phase medium

Phases of the same medium:

1/P

13

Another Case of Pressure Balance: NGC 985

Pressure Equilibrium

Similar kinematical properties

Marginal evidence of 3rd component

3 phase medium?1/P

Krongold et al. 2004 , ApJ in press

80ksec exposure with Chandra HETGS

14

Constraining the Structure and Location

of the Absorber

15

Constraining the Structure of the Absorber

Continuous Flow

Several Charge States of the same element

Averaged absorption is observed

No response to flux variations by factors < 3-5

Clumped Gas

Should respond even to moderate flux variations

Isolated Components vary as expected in PI

U Flux

Opacity variation in response to flux variations

16

Variability on NGC 3783 (LIP)

Bin size of 0.25 Å

Data Photoionization Equilibrium Model

Krongold et al. 2005, ApJ in press

2X flux increase

17

The UTA varies as expected in PI

Data Ratio Model Ratio

Significance ~10

18

Implications of Variability Variability observed in the UTA rules out a

Radial Continuous Flow of Ionization Stages If LIP in PI Using tobs as upper limit to recombination

time ne 104 cm-3

Using ne and U1/neD2 D < 6 pc (Reeves et al. 2004; Nicastro et al 1999; Netzer et al.

2002; Kriss and Blustin et al. 2003, Kaastra et al.2004)

ΔD < .15 pc Compact Absorber

Behar et al. (2003) D > 2 pc

19

Further Constraints of the Density

Most Determinations are Upper or Lower Limits

We need to constrain the density ne to constrain D

Diagnostics of n:

Atomic Physics (Kaastra 2004)

Time Evolving Photoionization Models (Nicastro 1999)

20

Constraining the Line Widths of the Absorber

Constraining the Geometry?

21

The width of the Lines Absorption Lines are not Resolved

We have to constrain the width of the Lines indirectly

Through Models • (Widths > 200 km s-1)

Through UV data • (Widths between 100-200 km s-1)

22

Voigt Profiles Convolution of Natural

and Doppler Broadening

Voigt Parameter a Γ/Δ

Not relevant in other bands

a << 1 Relevant in X-rays

a > 1(Inner shell Transitions) Affects the Depth at

the core of the line:

oNifulo

23

oNifulo

Fe Inner Shell vs. Outer Shell

)(

)(

v

vOUTERo

INNERo

OUTERo

INNERo

24

Constraining the GeometryUV data Constraints (Figure by Arav 2003)

UV widths >> X-ray widths UV widths ~ X-ray widths

UV

X-ray X-ray

Constraining the widths we can constrain the angle of the flow

TransverseFlow

25

Conclusions WA can be modeled with a Simple picture Fits almost all absorption features with only few free

parameters

3 or 2 phases Observed in other objects

(NGC 5548, Kaastra et al 2002; IRAS 13349+2438, Sako et al. 2001, etc.) Intrinsic property related to the structure of the nuclear

environment of AGN

Pressure equilibrium (and similar kinematics) Suggests pressure confinement

Observed Variability

Rules out a Radial Continuous flow clumped gas Better Diagnostics in ne and D

Better Diagnostics of the widths Geometry Consistent with transverse flow (consistent with UV

observations)