multiwavelength studies of agn: hylirg and red quasars

Multiwavelength studies of AGN: HyLIRG and red quasars

ngel Ruiz - IUCAA

Talk layout

Red quasars in the 2XMMi/SDSS cross-correlationSample selection

Optical analysis

X-ray analysis

Conclusions

Hyperluminous infrared galaxies in the IIFSCzSample selection

Comparison with WISE data

IR SED modelling

Conclusions

Red quasars in the 2XMi/SDSS-dr7 cross-correlation

A. Ruiz, R. della Ceca, F. Carrera, A. Caccianiga, P. Severgnini, S. Mateos

Red quasars - Introduction

Average QSO SED Richards+06

BBB responsible of blue colours in quasars (U-B early phase of AGN evolution, SMBH is still enshrouded in dust and gas clouds (Hopkins+04; Georgakakis+09; Banerji+12; Glikman+12)

Big Blue
Bump

Red quasars - Introduction

Average QSO SED Richards+06

Some evidence of intrinsically red quasars (Risaliti+03, Hall+06, Young+08)

Combined X-ray/optical data allow constraining the amount of dust.

Young+08: sample of 17 SDSS-dr3 red quasars observed with XMM-Newton 40% intrinsically red.

Nowadays, thanks to 2XMMi and SDSS-dr7, we can extent this studies with a significantly larger sample of red quasars.

Red quasars Sample selection

SDSS-dr7 quasar catalogue105,783 sources(Schneider+10)2XMMi catalogue
221,012 sources(Watson+09)2,344 quasars
(797 FLIX)

Pineau+11
& FLIX upper-limits

145 red
quasars

0.5 < z < 2.5(g i) 0.35(Richards+03)

Red quasars Relative colours

Relative colour definition:
(m1 m2) = (m1 m2) z

Avoid biases toward strong emission lines at certain redshifts.

z

g i

z

Red quasars Data analysis

Check for the presence of dust in our sources

Optical analysis:SDSS spectral fitting

Continuum shape (photometry)

X-ray analysisXMM-Newton spectral fitting

Hardness ratio

X-ray-to-optical flux ratio

Red quasars SDSS spectra

Reddening fit: E(B-V)

Power-law: F opt

Average spectra ofSDSS quasar
(Vanden Berk+01)

SMC
extinction curve
(Gordon+03)



Mild reddening

Strong reddening

Average SDSS quasarspectra at z = 1.5

Power-law: opt = 0.44

Normal blue quasar:
(u-r) ~ (g-i) ~ (r-z) ~ 0

Dust continuum:
(u-r) > (g-i)

Obscured PL
E(B-V) = 0.1

Red PL continuum:
(u-r) < (g-i)

Power-law
opt = -1

Red quasars Continuum shape

u-band photometry outside spectral range and more affected by dust.

Use relative colors to estimate the continuum shape

Red quasars Continuum shape

Dusty continuum (104 sources): E(B-V) > 0.15, or

(u-r) - (g-i) > 0

Red PL continuum (17 sources):E(B-V) < 0.15, and

(u-r) - (g-i) < 0

dust

redPL

Red quasars XMM spectra

79 out of 145 sources detected in the 2XMMi.

52 with high SNR X-ray spectra for fitting.

Two X-ray models:phabs * powerlaw

phabs * zphabs * powerlaw

Only 6 sources with detected absorption, NH upper-limits for the rest.

X-ray absorption criteria:

NH (or upper-limit) > 1022 cm-2

< 1.6

X-ray absorbed

X-ray
unabsorbed

Red quasars Hardness ratio

27 detected in X-rays but low SNR + 16 with inconclusive X-ray spectra.

Hardness ratios:
HRn = (CRn+1 CRn) / (CRn+1 + CRn),
n = 1 (0.2-0.5 keV), 2 (0.5-1 keV),
3 (1-2 keV), 4 (2-4.5 keV), 5 (4.5-12 keV)

HR2 most sensitive for NH ~ 1022

X-ray absorption criterion:HR2 > 0.1

z=0.5z=1.0z=1.5z=2.0z=2.5

Absorbed X-ray spectraUnabsorbed X-ray spectraInconclusive spectraLow SNR spectra

Red quasars X/O spectral index

66 sources with only flux upper-limit + 12 with inconclusive spectra or HR.

X-ray-to-optical flux ratio offers some information about X-ray absorption.

X-ray-to-optical spectral index:
ox = 0.384 * log F(2keV) / F(2500)

X-ray absorption criterion:

ox < -1.8

Red quasars Summary

Dusty reddened quasars:Dust in optical (104) or X-ray absorbed(52): 121 sources

Intrinsically red quasars:

Optical red PL (17) and low X-ray absorption (90): 10 sources

Unclassified: 14 sources

1011 L

ULIRG: LIR > 1012 L

HyLIRG: LIR > 1013 L

Trend with LIR of AGN content and AGN relative contribution.
(Veilleux+02; Farrah+06)

Local ULIRG: gas-rich mergers with on-going major star formation episodes and heavily dust-enshrouded AGN (Lonsdale+06).

This picture does not work well on high-z ULIRG or HyLIRG.
(Draper+12; Niemi+12; Rodighiero+11; Farrah+02)

HyLIRG Introduction

HyLIRG are composite sources: AGN and SB are both needed to explain their IR luminosities (Rowan-Robinson+00; Farrah+02; Verma+02; Ruiz+07; Ruiz+10; Ruiz+13)

Divided in two classes (Farrah+02;Ruiz+10):Broad IR bump, heavily obscured and large covering factors, in interacting systems: high-luminosity tail of local ULIRG population.

Roughly flat SED, with low obscuration and covering factors, in isolated systems: young galaxies during maximal star formation phase?

Larger sample to test these hypothesis:The Imperial IRAS Faint Source Catalogue (IFSCz; Wang+09, Rowan-Robinson+10) increase the number of known HyLIRG by a factor ~4 AND is unbiased toward AGN.

Evidence in the IIFSCz of a large population of HyLIRG with no AGN contribution (Rowan-Robinson+10).

Comparison of low-z HyLIRG with w1w2-dropouts:

Faint WISE sources barely detected at 3.4 and 4.6 but detected at 12 or 22 (Eisenhardt+12)

Heavily obscured high-z HyLIRG (peak at z~2-3), with IR emission dominated by hot dust heated by intense AGN activity (Bridge+12; Wu+12; Eisenhardt+12)

HyLIRG Introduction

HyLIRG Sample selection

IIFSCz: 60303 galaxies selected at 60 m from the IRAS Faint Source catalogue:Accurate positions, optical and NIR identifications.

Predicted LIR through SED modelling.

~55% spectroscopic redshifts, ~20% photometric redshifts.

HyLIRGs in the IIFSCz: 179 sources with LIR > 1013 L. 58 with spectroscopic z. Rest with photometric z.

Cross-match of this sample with WISE catalogue: 105 sources.

HyLIRG IIFSCz vs. WISE

Comparison between predicted fluxes by the SED models of the IIFSCz (Wang+09) and actual WISE measurements

SED model (Rowan-Robinson+08):Optical SED: 9 independent templates
(1 Elliptical, 4 Spirals, 1 SB, 3 QSO)

IR SED: AGN + SB templates

AGN: dusty torus

SB: M82, Arp220

Large discrepancies in the MIR.

HyLIRG IRAS vs. WISE

HyLIRG Our modelling

Fit of optical (12m)

Model as in IIFSCz:M82, Arp220 templates from SWIRE library (Polleta+07)

Significantly better predictions in the MIR.

Large population of SB-dominated HyLIRG with over-predicted MIR fluxes.

HyLIRG AGN contribution

HyLIRG WISE colours

AGN wedge(Mateos+12)

AGN wedge(Mateos+12)

HyLIRG w1w2-dropouts

w1w2-dropouts selection criteria (Eisenhardt+12):
f3.4 < 0.034 mJy and

f22 > 6.9 mJy, and

f22 / f4.6 > 1.97

f12 > 1.7 mJy, and

f12 / f4.6 > 1.38

OR

HyLIRG Summary

Large population of HyLIRG with NO AGN contribution!

Low-z HyLIRG and w1w2-dropouts show quite different properties in the MIR.

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multiwavelength studies of agn: hylirg and red quasars

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