Post on 14-Dec-2015
The Chandra/SWIRE Survey: Radio PropertiesOf X-Ray Selected AGN
Manuela MolinaINAF/IASF Milano
AGN9 – Ferrara, 24/27 May 2010
In collaboration with: M. Polletta, L. Chiappetti, L. Paioro (INAF/IASF-Mi), G.Trinchieri (OA Brera), F. Owen (NRAO) and Chandra/SWIRE Team.
Talk Outline
The XMM-Chandra/SWIRE Survey Description of the XMM Sample
X-Ray Variability (Chandra vs. XMM) X-Ray Variability vs. Obscuration and X-Ray Absorption
THE DATASET
X-RAY PROPERTIES OF THE XMM SAMPLE
Criteria for identifying AGN-driven radio activity Some examples of peculiar sources
RADIO PROPERTIES OF THE XMM SAMPLE
SUMMARY & CONCLUSIONS
AGN9 – Ferrara, 24/27 May 2010
Open Questions & Objectives
AGN FEEDBACK
AGN
Host Galaxy
AGN
Star Formation
Signatures of AGN feedbackIdentify efficiently radiating AGN and radio-
active AGNStudy and comparison of their properties
GOALS:
STRATEGY:Study of Radio and X-Ray Properties of an X-Ray
Selected AGN Sample with deep multi-frequency radio coverage
QUASAR or BRIGHT MODE
• AGN driven emission from sources close to Eddington limit• X-ray bright sources
(e.g. Di Matteo+05)
RADIO MODE• Mechanical Origin• Jets on small/large scales• Outflows and winds
(e.g. Croton+06)
The XMM-Chandra/SWIRE Survey in the Deep SWIRE Field
The Deep SWIRE Field Lockman Hole North RA = 10h45m, DEC = 58o58′ Area: 0.2 deg2
The Multi-l Data VLA @ 90 and 20 cm
(12mJy@5s) GMRT @ 50 cm MIPS @ 24, 70 and 160 mm IRAC @ 3.6, 4.5, 5.8 and 8.0
mm UH/UKIRT J, H, K KPNO Ugriz GALEX @ FUV (1500Å) and
NUV (2500Å) Chandra @ 0.3-8 keV (3
bands) XMM @ 0.3-10 keV (5 bands)
AGN9 – Ferrara, 24/27 May 2010
XMM-Newton
RED 0.5-2 keVGREEN 2-4.5 keVBLUE 4.5-10 keV
AGN9 – Ferrara, 24/27 May 2010
The Sample
Count rates and fluxes in 5 bands 3 Hardness Ratios NH estimated from Xspec or HR
93 sources with Chandra counterpart 71 with spectroscopic z 24 with photometric z All detected in Optical and/or Infrared (IR)
Selection: XMM Detected AGN (95)
FUV-Mid IR Spectral Energy Distribution (SED)
29%
8%38%
20% 4%
Source Classification
AGN1SY 1.8AGN2SFNA
38% UNOBSCURED
58% OBSCURED
AGN9 – Ferrara, 24/27 May 2010
Criteria for identifying AGN–driven radio activity
• q24<0.21: Radio Loud (RL)/ Radio Intermediate (RI)• 0.21<q24<1.45: Radio Quiet (RQ)• q24>1.45: Radio Weak (RW)
q24 parameterq24=Log(F24μm/F20cm)
<q24>=0.83±0.31 for RQ and SFGs (Appleton+04)
Radio Spectral Index
α20,50 (Sν∝ν-α)
• α20,50 <0.15: Inverted • 0.15≤α20,50≤0.5: Flat• 0.5<α20,50 <1.1: Steep• α20,50 ≥1.1: Ultra Steep
(Prandoni+09)
-1
1
2
inverted
ultra-steep
AGN9 – Ferrara, 24/27 May 2010
Radio Properties of the X-Ray Sources
RW/RL with typical α (0.2-1) Steep/Ultra-Steep are mostly RW and AGN1 Flat spectrum are generally RQ/RI Inverted spectrum are RQ
Opposite to UM expectations
Inverted spectrum sources tend to be absorbed and obscured. Steep/ultra-steep spectrum sources tend to be unabsorbed and unobscured.
AGN9 – Ferrara, 24/27 May 2010
Semimajor Axis Distribution
Redshift Distribution
Radio Semimajor Axis and z Distributions
AGN9 – Ferrara, 24/27 May 2010
A RW, Steep Spectrum Source
• Radio: synchrotron• b=2.2 arcsec • Lobes/host?• Radio Weak: no SF?
α20,50=0.7
Absorbed
AGN1 (Unobscured)
Fossil Synchrotron Emission?
Central engine and SF can no longer accelerate electrons
(e.g. Barvainis&Lonsdale 98)
AGN9 – Ferrara, 24/27 May 2010
Ultra Steep Spectrum Sources
α20,50=1.51
Unabsorbed
• Compact Source• Lobes/jets?• Radio Weak
Synchrotron emission from electrons which are cooling down due to the lack of a reacceleration mechanism.
(e.g. Barvainis&Lonsdale 98)
AGN9 – Ferrara, 24/27 May 2010
Inverted Spectrum Sources
• Extended Source• AGN driven radio emission• Radio Weak
Free-Free Absorption responsible for inverted spectrum?
α20,50=-0.07
Absorbed
SFG(Obscured)
A RL, Flat Spectrum Source
• RL• Compact• Beamed QSO?• Obscuration from host galaxy?
Radio emission indicative of Synchro-Self Absorption
α20,50=0.31Absorbe
d
AGN2 (Obscured
)
X-Ray Absorption vs Dust Obscuration
40%
12%
31%
14% 2%
44% Unabsorbed: Log(NH)<22
AGN1
SY 1.8
AGN2
SF
NA
• UNOBSCURED: 52%• OBSCURED: 45%
21%
6%
43%
25%6%
56% Absorbed: Log(NH)>22
AGN1
SY 1.8
AGN2
SF
NA
• UNOBSCURED: 27%• OBSCURED: 67%
Most of the absorbed sources are also obscured (e.g. Tajer+08)
Almost half of the unabsorbed sources are obscured
AGN9 – Ferrara, 24/27 May 2010
AGN9 – Ferrara, 24/27 May 2010
X-Ray Variability (Chandra vs XMM)
69%19%
12% Flux
Spec.
Flux+Spec.
Chandra (Sep. 2004) vs XMM (Oct. 2008/Apr. 2009)
A source is variable if |FCXO-FXMM|>2x(ΔFCXO+ΔFXMM)
i.e., more than 2σ flux variation in any band.
35% of the sources show variability, either in FLUX, SPECTRAL SHAPE or BOTH.
AGN9 – Ferrara, 24/27 May 2010
NH>102247%
NH<102253%
Variability vs. Absorption (NH)
X-Ray Variability vs Obscuration and Absorption
The fraction of unobscured and unabsorbed sources increases in the variable sub-sample
44%
9%31%
13% 3%
Variability vs Obscuration (SED Class)
AGN1
SY 1.8
AGN2
SF
NA
Var. Sources
All Sources
Unobscured
53% 38%
Obscured 44% 58%
Var. Sources
All Sources
Unabsorbed
53% 44%
Absorbed 47% 56%
Summary
• Radio properties and X-ray variability of a sample of 95 X-Ray detected AGN in the deep SWIRE field.
• AGN-driven radio activity identified through q24 parameter and radio spectral indexα20,50.
• Examples of peculiar radio sources.
• X-Ray Absorption vs. Dust Obscuration.
• X-Ray Variability vs. X-Ray Absorption and Dust Obscuration.
AGN9 – Ferrara, 24/27 May 2010
AGN9 – Ferrara, 24/27 May 2010
Conclusions
• Radio properties and X-ray variability of a sample of 95 X-Ray detected AGN in the deep SWIRE field.
• Efficiently radiating (X-Ray Bright) AGN are mostly RQ with typical radio spectra and contain only a few sources (3%) with AGN-driven radio activity.
• A certain number of X-Ray Bright AGN are RW, suggesting that any radio emission is the relic of a past AGN or SF activity.
• Inverted spectrum sources tend to be absorbed and obscured. Steep/ultra-steep spectrum sources tend to be unabsorbed and unobscured (is this in contraddiction with UM predictions?).
• AGN-driven radio emission is rare among X-Ray bright sources, suggesting that the quasar and radio feedback modes require different conditions and occur in AGN with intrinsic differences.
• Evidence of dying activty (radio-weak) in some AGN 1 : last phase of evolution?
AGN9 – Ferrara, 24/27 May 2010
Conclusions
• q24 andα20,50 provide good diagnostic tool for identifying “peculiar” sources
• Different kinds of radio emission processes related to different evolutionary stages, ages and physical properties of sources.
• Peculiarities observed in radio domain only
•Almost half of the unabsorbed sources are obscured
• Most of the absorbed sources are also obscured
• The fraction of unobscured and unabsorbed sources increases in the variable sub-sample
• Absorbed sources have flat/inverted radio spectra, while unabsorbed sources have steep/ultra-steep radio spectra, opposite to what expected from UM
AGN9 – Ferrara, 24/27 May 2010
X-Ray Variability
Variability vs SED Class
Variability vs X-ray Absorption
Flux Variability
10 Unobsc. AGN (36%) 11 Obsc. AGN (64%) 1 NA (4%)
Spec. Variability
4 Unobsc. AGN (66%) 2 Obsc. AGN (34%)Flux+Spec.
Variability
3 Unobscured AGN (83%) 1 Obscured AGN (17%)
44% AGN1 9% SY 1.8 53% UNOBSCURED 47% OBSCURED31%
AGN2 12% SF
Log(NH)<2253%
76% Flux 6% Spectrum 18% Flux+Spec.
Log(NH)>2247%
60% Flux 33% Spectrum 7% Flux+Spec.
Variability is NOT related to SED Class
As expected, unobscured sources tend, on average, to be more variable than obscured ones
AGN9 – Ferrara, 24/27 May 2010
Radio Properties of the X-Ray Sources
Lx<1044 erg s-1
obsc.
AGN
unobsc. AGN
Lx>1044 erg s-1
obsc.
AGN
unobsc. AGN
• Median Obsc. = 0.76• Median Unobsc = 0.73• Unobsc. AGN have slightly flatter radio spec. indices.• KS test suggests subsets might belong to same population of sources.
• Median Obsc. = 0.58• Median Unobsc = 0.85• Unobsc. AGN have slightly flatter radio spec. indices• KS test suggests that the two subsets belong to different populations.
AGN9 – Ferrara, 24/27 May 2010
Radio Properties of the X-Ray Sources
Is there a correlation between SED type and radio spectral index?
Vir Lal & Ho (2010) find, in a radio-selected sample, a prevalence of sources with flat and highly inverted radio spectra. They also suggest that flat radio spectra are more frequent in type 2 quasars than in type 1, challenging UM.
Bimodality in distributions Unobscured AGN peaking at around 0.6 and 0.3 Obscured AGN peaking at around 0.7 and 0.2 Are Obscured and Unobscured AGN from the same population of sources? KS test hints at a different population Obscured AGN also seem to have slightly flatter radio spectra than unobscured ones.