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X ray obscurers: bridging the gap between warm
absorbers and ultra-fast outflowsJelle S. Kaastra
SRON Netherlands Institute for Space Research &
Leiden University
Ehud Behar, Stefano Bianchi, Graziella Branduardi-Raymont, Massimo Cappi, Elisa Costantini, Barbara de Marco, Laura di Gesu, Jacobo Ebrero, Jerry Kriss, Junjie Mao, Missagh
Mehdipour, Uria Peretz, Pierre-Olivier Petrucci, Gabriele Ponti, Dom Walton
1. First high-resolution spectrum of an AGN
2
NGC 5548, 11 December 1999, 86 ks, Chandra LETGSBlueshifted absorption lines from photoionised gas: wind
(Kaastra et al. 2000)
What have we learned from study of these winds?
• Relatively persistent features, variability through ionisation changes
• Multiple velocity components 0 – 1000 km/s• Multiple ionization phases log 𝜉 from 0 – 4• Moderate column density NH< 1027 m-2
• Majority of ionising photons transmitted• In some cases @ distance of torus(review see e.g. Blustin et al. 2005; Laha et al. 2014)
3
2. Ultra-fast outflows
4
PDS 456 – Nardini et al. 2015v = -75000 km/s
PG 1211+143 – Kriss et al. 2018v = -17000 km/s
UFO’s
• strongly transient phenomenon• velocities 10 000 – 100 000 km/s• high ionisation: log 𝜉 from 3 – 5• high column density: NH ~ 1026 – 1028 m-2
• majority of ionising photons transmitted• large covering factor?• Likely close to the black hole (102 – 104 RS)• Large kinetic power
(See e.g. Tombesi et al. 2011, 2012)
5
3. Obscuration in NGC 5548
6
1 10 1000.1
110
100
Pho
tons
m−2
s−1
Å−1
Energy (keV)
Chandra 2002
NuSTAR 2013
INTEGRAL 2013
pn 2013
RGS 2013
Kaastra et al. 2014
Properties of the obscuring matter
7
• Outflowing with v=5000 km/s, broad profile• Two components:• Comp 1: log ξ = -1.2, NH=1026 m-2,
produces UV Broad Absorption Lines• Comp 2: almost neutral, NH=1027 m-2
• Partial covering inner BLR è distance few light days• Obscuration ongoing already for 8 years
Geometry of obscurers
8Credit: Renaud Person
Dehghanian et al. 2019
Effects of obscuration
9
1 102 5 200
0.2
0.4
0.6
0.8
1
Tran
smis
sion
Restframe wavelength (Å)
Total obscurer and WA 2013Obscurer 2013WA 2013WA 2002
• Modifies transmission WA due to recombination (de-ionisation)
• Modifies EUV SED èimplications for BLR modeling
• Shielding effect allows acceleration (UV-driven)
• At low X-ray resolution, neglect obscuration would lead to wrong continuum
Another case: NGC 3783
10
• Joint XMM-Newton/HST/NuSTAR/Swift• ToO in Dec 2016
See Mehdipour et al. 2017
Recurring obscuration in NGC 3783
11
1 10
110
Phot
ons
m−2
s−1
Å−1
Wavelength (Å)
22−8−2016
102 5 20
110
100
Phot
ons
m−2
s−1
Å−1
Wavelength (Å)
1993
1996
2000 (x 2)
Moderate obscuration, NH 10x lower than in Dec 2016, but still 2x1026 m-2
(Kaastra et al. 2018)
HETGS
NuSTAR
Obscuration
ASCA
Obscuration
Obscuration frequency
12
2.03.04.05.06.07.0
10−1
4 erg
cm
−2 s
−1 AÅ
−1
NGC 3783 SwiftUVOT (UVW2)
0.00.20.40.60.81.01.21.4
coun
t s−1
XRT (Soft)XRT (Hard)
0 50 100 150 200 250 300 350 400 450 500 550 6000Days − 57500 MJD (22/04/2016)
−0.20.00.20.40.60.81.0
(H−S
) / (H
+S)
0 50 100 150 200 250 300 350 400 450 500 550 6000Days − 57500 MJD (22/04/2016)
−0.20.00.20.40.60.81.0
(H−S
) / (H
+S) XRT X−ray HRMay−Jun
2014Jan−Feb2009
Jan−Feb2008
Swift hardness NGC 3783
Sparse info on how often and in how many AGN obscuration occurs
Some best-studied cases:NGC 5548 (Kaastra et al. 2014)NGC 3783 (Mehdipour et al. 2017)Mrk 335 (Longinotti et al. 2013)NGC 985 (Ebrero et al. 2016)NGC 3227 (Turner et al. 2018)
Obscured
notobscured
Summary & conclusions
13
v (km/s) log 𝜉 log NH Shielding Distance
“Warm absorber”
300 0-3 <27 low large
Obscurer 3000 <0 <27 high medium
UFO 30000 3-5 <28 low small
Simplified representation
• Obscuring material has large impact on its environment
• likely part of disk wind, close to BLR• Physics complex due to strong shielding• Simultaneous UV/X-ray spectroscopy is key• Obscuration cannot be ignored in modelling
Credit: Renaud Person