A new look at AGN Xray spectra

1

• A new look at AGN X-ray spectra
• the imprint of massive and energetic outflows

Ken Pounds University of Leicester
Prague August 2006
2
XMM-EPIC spectra for sample of type 1 AGN
L2-10 (1042 ergs/s) 570 175
40 6
1H 0419 NGC 509 NGC 5548 Mkn 766
most obvious feature is the soft excess - a
function of luminosity ? also fluorescent Fe K
line, sometimes with red wing

3
but the same spectral features (and changes) are
seen for individual AGN
example
- the luminous Seyfert 1 PG1211143
XMM pn data from 2001 (black) and 2004 (red)
observations
4
Appearances can be deceptive - compare the
unmodelled data
difference lies between 0.7 and 2 keV due to a
change in photoionised absorption?
5
Spectral ratio supports change in ionised
absorption as cause of spectral difference
2001/2004 data
Gierlinski and Done (2004) and Chevallier et al
(2006) have explored this idea as an explanation
of strong soft excesses. Problems with
relativistically smeared absorber and with fine
tuning
6

Could another component be moderating the
spectral change?
Fluxed spectra of the highly variable Seyfert 1H
0419-577 ()

• difference spectra showed dominant spectral
  change due to steep power law component (Gamma
  2.4)

Pounds et al, ApJ 2004
7
PG1211 exhibits a high velocity outflow which,
unless highly collimated, has a mechanical energy
comparable to the bolometric luminosity (more
strictly v/c if continuum driven)
Could this power the steep, variable continuum
component ?
Pounds et al MN 2003 King and Pounds ApJ 2003
But lower velocity claimed by Kaspi and Behar,
ApJ 2006
8
analysis of higher resolution XMM MOS data has
improved constraints on high energy outflow
() K-shell absorption from H- and He-like ions
of Ne, Mg, Si, S and Fe gtgt v0.14/-0.01c
Pounds and Page (astro-ph 0607099)
9
Developing a new spectral model
components include power law continuum from
disc-corona absorption by high and moderate
ionisation gas re-emission from ionised gas
components second (power law) continuum powered
by outflow
10
the result - an excellent spectral fit to the
EPIC data (chi_sq 840/830 dof) - - with no
smearing
11
Compare energies and luminosities as further test
of model

• Absorption by warm absorber 8.4 x 1043 ergs/s
  from PL1 and 5.3 x 1042 ergs/s from PL2
  gtgtgt 9 x 1043 ergs/s

Luminosity of warm emitter 1.7 x 1043 ergs/s
gtgtgt CF 0.2

• Absorption by high Xi absorber 1.4 x 1043
  ergs/s from PL1 and 5 x 1042 ergs/s from
  PL2 gtgtgt 1.9 x 1043 ergs/s

Luminosity of high Xi emitter 1.4 x 1042 ergs/s
gtgtgt CF 0.1

• Luminosity (0.35-10) in second power law 6 x
  1043 ergs/s
• while mechanical energy in fast flow and CF of
  0.1 6 x 1044 ergs/s gtgtgt efficiency 10

NB warm emission 35 x that of NGC1068 (but only
5-10 x higher Lbol)
12
Critical fit to high resolution RGS data -
yes, but requires emission lines
to be strongly broadened
Steep power law continuum consistent with EPIC
model
13
the broadened emission line structure in the RGS
spectral fit N, O, Ne, Mg removed from XSTAR
model Fe also removed, to leave continuum only
14
Finally - how does the same model fit the 2004
data?
primarily by increase in weakly absorbed power
law
15

• Summary
• blue-shifted absorption lines in the luminous
  Seyfert 1 galaxy PG1211143 show highly ionized
  outflow at v 0.14c
• the mechanical energy in the high velocity
  outflow is sufficient to power a second X-ray
  continuum component perhaps via internal shocks
  in the flow (NB efficiency similar to GRB ?)
• re-emission of the absorbed flux from primary
  power law visible in the soft X-ray spectrum
  (strong line broadening)
• the need for a relativistic Fe K line is reduced
  or removed by the spectral curvature caused by
  continuum absorption
• similar spectral features in other luminous AGN
  suggest PG1211 143 may be characteristic of a
  high accretion ratio
• NB. outflow of 1 MSun/ yr for 5x107 yr will
  carry mechanical energy to host galaxy 1060
  ergs ( cf binding energy 1059 erg of galactic
  bulge with M 1011 MSun and velocity dispersion
  300 km/ s gtgtgt major effect on growth of
  host galaxy

16
(No Transcript)
17
Scaling the ionised outflow components
Warm absorber/emitter
Ionisation parameter gtgtgt
n.r21043.7/35 2 x 1042 column
density gtgtgt n.d 8 x 1022
assume d 0.1r gtgtgt r 2 x 1018
cm and n 5 x 105 cm-3
Emission measure 1066 cm-3 from observed
luminosity spherical shell with
above parameters gtgtgt n2 . volume 3 x 1066 cm-3
gtgtgt CF 0.3
High Xi absorber/emitter Ionisation parameter
gtgtgt n.r21043/750 1.3 x 1041 column
density gtgtgt n.d 6 x 1022
assume d 0.1r gtgtgt r 2 x 1017 cm
and n 4 x 106 cm-3
Emission measure 2 x 1065 cm-3 from observed
luminosity spherical shell with
above parameters gtgtgt n2 . volume 2 x 1064 cm-3
gtgtgt CF 0.1

18

• EPIC (and RGS) spectra show evidence for
  outflowing matter with wide range of ionisation
  parameter.
  
• Unless tightly collimated the high velocity
  implies
• a high mass rate with Mdot.out 1.0 MSun/yr,
  comparable to Mdot.Edd 1.2 MSun/yr for a BH
  mass of 3 x 107 MSun accreting at an efficiency
  of 0.1, and
  
• an energetic outflow 2 x 1044 erg/s (v/c x
  LEdd) with mechanical energy significantly larger
  than the luminosity of the X-ray PL

NB. outflow of 1 MSun/ yr for 5x107 yr will
carry mechanical energy to host galaxy 1060
ergs ( cf binding energy 1059 erg of galactic
bulge with M 1011 MSun and velocity dispersion
300 km/ s hence will have a major effect on
growth of host galaxy
19
But is the spectrum compatible with no strong
narrow lines in RGS?- model fit (PO2 EM1)
requires smoothing to get acceptable chi-sq-
find similar ratio of line emission to continuum
and PL slope is again
steep (Gamma 3)
However, best-fit sigma 18 eV at 0.5 keV
Corresponds to v 25000 km s-1
FWHM
additional broadening from line saturation,
turbulence or spread in ionisation parameter?
20
Consider the case of PG1211143 - where an
energetic outflow is well established
PG1211143 is a bright, narrow emission line
quasar at z 0.0809
Lbol 6 x 1045 ergs/s
(H0 75)
MBH 3 x 107 MSun
suggesting accretion rate Eddington rate

Pre-XMM
observations showed a strong soft excess over
a PL of photon index 2, with some evidence for
a broad Fe K line XMM made a 60 ks observation
of PG1211143 in June 2001 and second
similar observation in June 2004
21
Lyman-alpha of FeXXVI
MgXII SXVI


Identification of narrow absorption lines in EPIC
pn and MOS with resonance lines of H- like ions
of Fe, S, and Mg, consistent with high
ionisation, high column density outflow of v
0.08 0.1c see also
IC4329A (Markowicz et al astro-ph/0604353)
22
a closer look at the MOS data for PG1211
in particular the absorption features at 1.5
and 2.7 keV are both resolved into two lines
23
best fit now if 7 keV feature is identified with
1s-2p resonance absorption line of Fe XXV
24
Finally - testing the new model with 2004 pn data

• abundances fixed at 2001 values
• fit acceptable (chi-sq / dof 1.1)
• reduced absorption modelled mainly by stronger
  steep power law component
• weaker soft X-ray emission as indicated by
  difference spectrum

25
The initial analysis used 4 of the 5 most
significant absorption features to find an
outflow velocity of v0.09c.
26

• - ignoring absorption near the Si edge and an
  emission line

27
Addition of a trace absorber affecting PO2
improved chi-sq from 877/817 to 832/814
NH1.2x1021 cm-2 log Xi
1.95 v_out 0.07 0.10 c
Removing absorber shows absorption due to Fe-L
and UTA
28
Initial ratio of 2004 data to 2001 model
New fit with increase in PO2 and weaker soft
X-ray line emission
29
a closer look at the MOS data for PG1211
conventional plot with PL fit at 1-10 keV -more
spectral structure seen below 3 keV
30
(No Transcript)
31
(No Transcript)
32
(No Transcript)
33
(No Transcript)
34
But, individual AGN show very similar spectral
variations
1H 0419-577 in bright, high flux state and
faint, low flux state
Perhaps accretion rate is the key?
35
(No Transcript)
36
Conventional analysis of EPIC spectrum (pn
black MOS red) reported in 2003 paper
Power law fit at 1-10 keV found a photon index
1.85 and a strong SX
1-10 keV spectrum modelled with a power law plus
an extreme relativistic line Fe K emission line
(EW 1.4 keV)

Plus narrow
absorption features at 1.5, 2.7, 7 and 8 keV
(MNRAS, 345, 705, 2003)
37
MOS has equally good statistics at medium and low
energies and better energy resolution (1
sigma34 eV at 1 keV)
Part of MOS spectrum of NGC 1068
(MNRAS,
368, 707, 2006)
38
Chi-sq plot shows high significance of the 5
absorption lines and (the same) emission lines
() as seen in pn data
higher resolution MOS spectra confirms the
strong, highly ionised outflow in PG1211 143,
albeit with velocity increased to v0.12c
39
The fitted model includes power law continua with
photon indices 2.1 and 3
plus
high ionisation absorber A1 and
warm absorber A2
affecting both power lawsE1,E2 re-emission from
absorbing gas

NH2x1023 A1 log Xi 2.9
v_out 0.120/-0.005c
NH3x1022 A2 logXi 1.5
v_out 0.05/-0.02c
logXi 1.4 E1 v_out
3000/-1000 km/s
logXi 2.9 E1 v_out
3000/-1000 km/s
Chi-sq/d.o.f. 820/820

40
Does model describe spectral change in 2004 ?
-- the plot shows pn data from 2001 (black) and
2004 (red)
the main spectral change appears to be an
increase in flux between 0.7 2 keV narrow
absorption lines remain, but weaker

41
Footnote Variability of EPIC light curve also
supports model
2-10 45
1-2 40
32 flare over 104 sec in full 0.3-10 keV light
curve
variation least in soft X-ray band as expected
for significant re-processed flux
0.3-1 25