1. X-RAY NATURE of the LINER nuclear sources Isabel Márquez (IAA, Spain) 1. Introduction 2. The sample and the data 3. Reduction and analysis X-ray data: Spectral analysis Imaging CC diagrams OPTICAL: HST imaging 4. Discussion 5. Conclusions “X-Ray Nature of the LINER Nuclear Sources” O. González-Martín, J. Masegosa, I. Márquez, M.A. Guerrero et D. Dultzin-Hacyan A&A, in press. Astro-ph/0605629

2. 1.INTRODUCTION AGNs (Active Galactic Nuclei) produce high luminosities in very compact regions, usually temporaly variable (from hours to years) Therefore, more efficient (E/mass) than normal stellar processes Importance of low luminosity AGNs (LLAGN) - most of AGN population - eventual connection active/non-active nuclei Difficult detection - extinction - associated star formation in circumnuclear regions

3. 1.INTRODUCTION LINERs (Low Ionization Emission-line Regions) Group within LLAGNs Heckman 80: optical spectra dominated by low ionization emission lines [OII] 3727 /[OIII] 5007 ≥ 1 [OI] 6300 /[OIII] 5007 ≥ 1/3 Typically less luminous than Seyferts and QSOs Are them AGNs? The nuclear emission, is it originated in starbursts or from the accretion onto a black hole?

4. 2. THE SAMPLE AND THE DATA Multiwavelength Catalogue of LINERs (MCL) (Carrillo+ 99): - 476 galaxies classified as LINERs - Information from radio to X-ray CHANDRA: high resolution! Chandra ACIS archival data, public observations to Nov. 04 : 137 gxs Re-analysis op emission lines: 122 LINERs (5 SB, 6 Sy, 4 transition) Enough counts (at least 25 counts 0.5-10 keV): 51 LINERs 45 ACIS-S, 6 ACIS-I + HST imaging 45/51 from different programs 31 F814W (F606W or F702W)

5. MCL: empty histogram LINERs: normal spirals M B = -20.0 +- 1.5 R-X: earlier Ss (selection bias) Most from Ho+ 97 ULIRGs (N6240, U8696, U5101) Abell 1795 Hickson 16 10 10 erg s -1 SAMPLE REPRESENTATIVE OF BRIGHT LINERS, no for the most luminous in FIR

6. SPECTRAL FITTING: 0.5 – 10 keV with XSPEC v.11.3.2 binned for 20 counts/bin before background subtraction (CRPPHA) 23 objects: SF subsample (spectral fitting) Two models: 1. power law Γ 2. emission from an optically thin plasma kT Raymond-Smith or MEKAL + absorption (phabs) N H Solar abundances Statistics Χ 2 FTEST for 2nd component 3. REDUCTION AND ANALYSIS 3.1 X-RAY DATA

7. 3 bad fitting 1 purely thermal N6482 7 only power law N3690B, N4374, N4395, N4410A, N4594, N4696, N5746 15 gals combined model (FTEST) N4261 too complex N2681 and N7130, Bad statistics

8. N H ~ 0.1 – 2.9 x 10 22 cm -2 kT ~ 0.64 +- 0.17 keV  ~ 1.89 +- 0.45 L(2-10 keV) ~ 1.4x10 38 – 1.5x10 42 erg s -1

9. Method for estimating L(2-10 keV)  = 1.8 and N H = 3x10 20 cm -2 (galactic absorption) < factor 3

10. X-ray data. Imaging analysis We define the following bands: 0.6 – 0.9 keV SA 0.9 – 1.2 “” HA 1.2 – 1.6 “” SB 1.6 – 2.0 “” HB 2.0 – 4.5 “” SC 4.5 – 8.0* “” HC *excluding 6-7 keV Morphology: - AGN candidates: unresolved, 30/51 (N4594) - SB candidates: no source 21/51 (CGCG162-010) SB candidate soft medium 2MASS 6-7 keVHTS hard medium hard 6-7 keV AGN candidate soft HST2MASS

11. = 1.7 +- 1.5x10 39 erg s -1 = 1.2 +- 1.3x10 40 erg s -1

12. X-ray data. color-color diagrams Hardness ratios: Q i = (H i -S i )/(H i +S i ) i= A, B, C calculated for errors in S,H < 80% Models with G : 0.4 – 2.6 KT: 0.1 – 4.0 KeV N H : 1-30 x 10 20 cm -2 combined: 50% a 1keV, 10 20, 10 22 N6240  [0.8 – 1.0] 1.03 +- 0.14 kT [0.7 – 0.8] 0.76 +- 0.06 keV N H [~10 22 ] 1.1 +- 0.1x10 22

13. N315 N6251 IC1459 N7130 N5194 N315: kT=0.51 (Donato+ 04) jets X N6251, IC1459: PL+RS ≠ PL+MK

14. 3.2.HST imaging “Sharp-dividing” Classification: Compact (C): knot in X-ray nucleus (35) (N4552) Dusty (D): central dust, no knot (8) (N4438)

15. 4. DISCUSSION 59% (30/51) AGN candidates SB candidates: no AGN or obscuration -AGNs more luminous on average, but large common range - Comparison of morphological class with Ho+ 01,Satyapal+04: OK - Comparison of luminosities Ho+ 01, Satyapal+ 05: OK - Chandra ACIS spectra: soft thermal + hard power law kT ~ 0.6 -0.8 keV G ~ 1.0 – 4.3, 1.8 SB similar (Ott+ 05, AGN > 1.4: Sy1:1.56 (Cappi+ 06) Grimmes+05) Sy2:1.61 Sy1 kT ~ 0.25 keV Similar N H ( ~ 10 20 -10 22 cm -2 ) for Sy Luminosities within the range for Sys ORIGIN of X-RAY EMISSION X? (Flohic+06: 19 (12) LINERs,idem %) LINERs like a low luminosity version of AGN?

16. 4. DISCUSSION OPTICAL All AGN-X show compact HST nuclei (28 gxs) LINERs SB-X with HST (15 gxs): 8 D-HST (5 low N H ) 7 C-HST with: N4696 N H, broad H a N3245 2 peaks H , radio N4314, N7331: radio RADIO AGN: unresolved radio core + flat continuum (Nagar+ 05, Filho+ 04) 16/51 observed in radio with useful data 13 AGN radio - 9 AGN-X - 4 SB-X : 3 with 5” resolution N5866 AGN-radio, also in X? 3 SB radio - 2 SB-X - 1 AGN-X N4636 UV variability 7 in common with Maoz+05, 5 variable at UV, all of them AGN-X HMXRB? Stellar populations: life time for HMXRBs 10 6 – 10 7 yr 14/51 in Cid-Fernandes+ 04 & González Delgado+ 04: only N3507 27% < 10 8 yr the others, < 3%

17. 4. DISCUSSION LX/L[OIII] as a measure of Compton thichkness for Sys log (LX/L[OIII]) < 0 Compton thick Greater percentage of Compton-thick objects for SB candidates A larger percentage of AGN LINERs ? (Fe line, XMM) Maiolino+98 Bassani+99 Panessa & Bassani02 Cappi+06 Panessa+06

18. 5. CONCLUSIONS Study of nuclear properties of a sample of galaxies with LINER nucleus Morphological classification: 59% AGN-X candidates Spectral fitting: thermal + power law Overlapping luminosity ranges, AGN-X more luminous on average CC diagrams: interesting for obtaining physical parameters without spectral fitting All the AGN-X LINERS are C-HST, 8/14 SB-X are C-HST Evidences at radio, UV Contributions from HMXRBs (stellar populations) Simplest hypothesis: low level nuclear activity Compton thick objects more numerous in SB candidates, increase the number of AGN-LINERs?