THECHANDRAHRC VIEW OF THE SUBARCSECOND STRUCTURES IN THE NUCLEAR REGION OF NGC 1068

Abstract

We have obtained a high spatial resolution X-ray image of the nucleus of NGC 1068 using the High Resolution Camera (HRC-I) on board the Chandra X-ray Observatory, which provides an unprecedented view of the innermost 1 arcsec radius region of this galaxy. The HRC image resolves the narrow-line region into X-ray emission clumps matching bright emission-line clouds in the HST [OIII] λ5007 images and allows comparison with subarcsecondscale radio jet for the first time. Two distinct X-ray knots are revealed at 1.3-1.4 arcsec northeast and southwest of the nucleus. Based on the combined X-ray, [O iii], and radio continuum morphology, we identify the locations of intense radio jet-cloud interaction. The [O iii] to soft X-ray ratios show that some of these clouds are strongly affected by shock heating, whereas in other locations the jet simply thrusts through with no signs of strong interaction. This is further strengthened by the presence of a kT ∼ 1 keV collisionally ionized component in the ACIS spectrum of a shock-heated cloud HST-G. We estimate that the kinematic luminosity of the jet-driven shocks is 6 × 10 38 erg s −1 , a negligible fraction (10 −4 ) of the estimated total jet power.

The warm molecular gas and dust of Seyfert galaxies: two different phases of accretion?

“…7, for NGC 1386) and is coincident with the extent and morphology of the narrow-line region traced by the [OIII] ionized gas (Capetti et al 1997;Bianchi et al 2006;Wang et al 2012), suggesting that both the diffuse X-ray and the [O III] emission are produced by the same gas photoionized by the nuclear continuum (e.g. Iwasawa et al 2003;Wang et al 2012). The extension of the nuclear 0.3-10 keV band X-ray emission is also comparable to the nuclear warm H2 2.1 × 10 −15 * Predicted H 2 2.12µm fluxes assuming a conservative filling factor of 10%.…”

HIFI Spectroscopy of H2O Submillimeter Lines in Nuclei of Actively Star-forming Galaxies

“…The filled squares in Figure 7 given in the plot legend, while the values for other parameters are presented in Table 4. 01 line ratio varies from -0.5 2.0 in galaxies with kinetic temperature around 20-30 K (e.g., Cen A, NGC 4945, and NGC 253), to the extreme large values (~-10 40) in galaxies with  -T 80 100 k K, which are well known to harbor "shocked gas" (e.g., NGC 6240 and NGC 1068; Müller Sánchez et al 2009;Wang et al 2012Wang et al , 2014Meijerink et al 2013;Papadopoulos et al 2014). As such, we suggest that the -2 1 12 01 / -1 1 10 01 line ratio can be utilized as a good indicator of "shock condition" where gas is heated to high kinetic temperatures.…”

Revisiting the complex kinematics of ionized gas at the central region of NGC 1068: evidence of an additional active galactic nucleus?

“…To investigate whether the 2nd AGN scenario is consistent with other observational signatures, we use X-ray and radio data and search for evidence of multiple cores at the central region. Starting with X-ray data, we check the Chandra high-resolution camera (HRC) data of NGC 1068 (Ob-sID: 12705; PI: Fabbiano), which were previously presented by Wang et al (2012) 2012), the Chandra image with the PSF deconvolution resolves another putative X-ray point source at 3.6 NE of the nucleus (∆RA= +2.00 , ∆Dec= +2.75 . The detection of the point source is significant at the >7σ level when we take into account the Poisson noise of the adjacent pixels.…”

“…To further investigate the origin of the X-ray point source, we measure the [O III]/soft X-ray ratio, which is a tracer of ionization states (Bianchi et al 2006). By investigating the ratio for several X-ray knots in the central region of NGC 1068, Wang et al (2012) reported that a few of them were originated from shocks. Using the same data set and method of Wang et al (2012), we find the ratio of ∼ 8.6 ± 0.86 at the pixel of the X-ray point-source position (i.e., within the extraction area of 0.13 × 0.13 ).…”

“…By investigating the ratio for several X-ray knots in the central region of NGC 1068, Wang et al (2012) reported that a few of them were originated from shocks. Using the same data set and method of Wang et al (2012), we find the ratio of ∼ 8.6 ± 0.86 at the pixel of the X-ray point-source position (i.e., within the extraction area of 0.13 × 0.13 ). This result indicates photoionization rather than shock.…”