The Central Gas Systems of Early-Type Galaxies Traced by Dust Features, Based on the [ITAL]HUBBLE SPACE TELESCOPE[/ITAL][ITAL]Hubble Space Telescope[/ITAL] WFPC2 Archival Images

Tomita, Akihiko; Aoki, Kentaro; Watanabe, Masaru; Takata, Tadafumi; Ichikawa, Shinichi

doi:10.1086/301440

Cited by 54 publications

(81 citation statements)

References 15 publications

(34 reference statements)

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“…An irregular dust distribution is present in the nuclear region of IC 1459 (Goudfrooij et al, 1990). Although on average this provides too little reddening [E(B-V)=0.07, or 4×10 20 cm −2 for standard dust to gas ratio and composition] to hide an AGN, the obscuration could well be much greater near the nucleus (Tomita et al 2000). In this case, however, we would expect to see the 'missing' luminosity in the infrared.…”

Section: Hiding the Emission: Obscurationmentioning

confidence: 96%

The X‐Ray–faint Emission of the Supermassive Nuclear Black Hole of IC 1459

Fabbiano

Elvis

Markoff

et al. 2003

ApJ

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Chandra observations of the supermassive black hole in the nucleus of IC 1459 show a weak (L X =8×10 40 erg s −1 , 0.3-8 keV), unabsorbed nuclear X-ray source, with a slope Γ = 1.88±0.09, and no strong Fe-K line at 6.4 keV (EW<382 eV). This describes a normal AGN X-ray spectrum, but lies at 3×10 −7 below the Eddington limit. The SED of the IC 1459 nucleus is extremely radio loud compared to normal radio-loud quasars. The nucleus is surrounded by hot ISM (kT∼0.5-0.6 keV) with an average density of 0.3 cm −3 , within the central ∼180 pc radius, which is comparable to the gravitational capture radius, r A ∼140 pc. We estimate that for a standard AGN efficiency of 10%, the Bondi accretion would correspond to a luminosity of ∼6×10 44 erg s −1 , nearly four orders of magnitude higher than L X . ADAF solutions can explain the X-ray spectrum, but not the high radio/X-ray ratio. A jet model fits the radio-100µm and X-ray spectra well. The total power in this jet is ∼10% of L Bondi , implying that accretion close to the Bondi rate is needed.

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Section: Hiding the Emission: Obscurationmentioning

confidence: 96%

The X‐Ray–faint Emission of the Supermassive Nuclear Black Hole of IC 1459

Fabbiano

Elvis

Markoff

et al. 2003

ApJ

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“…Veron-Cetty & Veron 1988;van den Bergh & Pierce 1990;Michard 1999), although already Bregman & Roberts (1990) reported extended dust features ≈100 east from a private communication by J. L. Tonry. After a first non-detection of dust in the very center of M 86 (Tomita et al 2000), a central dusty disk has eventually been found by Tran et al (2001).…”

Section: Introductionmentioning

confidence: 99%

Deep ISOPHOT far-infrared imaging of M 86

Stickel

Bregman

Fabian

et al. 2002

A&A

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Abstract. Deep far-infrared (FIR) imaging data obtained with ISOPHOT at 60 µm, 90 µm, 150 µm, and 180 µm reveal a complex FIR morphology of the Virgo cluster elliptical M 86 (NGC 4406). A close pair of sources is associated with the centre of the M 86 galaxy and optically discovered dust streamers. Both components have a cold FIR spectrum from the thermal emission of dust with a temperature of ≈18 K. A compact off-center source lying ≈3.5 north-west is likely an unrelated background source. The brightest FIR source long-wards of 90 µm consists of a compact central core surrounded by an extended halo. It lies close to the nearby spiral galaxy NGC 4402 at the position of the strong northern depression in X-ray brightness. It represents the first detection of an intergalactic dust cloud in the intergalactic region between galaxies. Additionally, three much fainter FIR sources are detected in the field. The ISOPHOT data do not support the earlier suggestion based on IRAS and X-ray data that the unresolved north-western component is cold dust removed from M 86 by ram pressure stripping. The observational evidence suggests that at least for the overall FIR morphology, gravitational interactions between M 86 and neighboring galaxies are much more important than ram stripping of dust. Moreover, the X-ray morphology appears to be partially affected by dusty foreground absorbers. Since M 86 is not showing signs of ongoing stripping of interstellar dust by the intra-cluster medium, a clear case for this dynamical interaction has yet to be found.

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“…, (13) Nikołajuk & Walter (2013), (14) Tomita et al (2000), (15) Nicholson et al (1997), (16) Elmegreen et al (1998), and (17) Randall et al (2009 …”

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confidence: 99%

Synapses of active galactic nuclei:

González‐Martín

Díaz-González²,

Acosta–Pulido

et al. 2014

A&A

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Context. Many classes of active galactic nuclei (AGN) have been defined entirely through optical wavelengths, while the X-ray spectra have been very useful to investigate their inner regions. However, optical and X-ray results show many discrepancies that have not been fully understood yet. Aims. The main purpose of the present paper is to study the synapses (i.e., connections) between X-ray and optical AGN classifications.Methods. For the first time, the newly implemented  task allowed us to analyse broad band X-ray spectra of a sample of emission-line nuclei without any prior spectral fitting. Our sample comprises 162 spectra observed with XMM-Newton/pn of 90 local emission line nuclei in the Palomar sample. It includes, from the optical point of view, starbursts (SB), transition objects (T2), low-ionisation nuclear emission line regions (L1.8 and L2), and Seyfert nuclei (S1, S1.8, and S2). We used artificial neural networks (ANNs) to study the connection between X-ray spectra and optical classes. Results. Among the training classes, the ANNs are 90% efficient at classifying the S1, S1.8, and SB classes. The S1 and S1.8 classes show a negligible SB-like component contribution with a wide range of contributions from S1-and S1.8-like components. We suggest that this broad range of values is related to the high degree of obscuration in the X-ray regime. When including all the objects in our sample, the S1, S1.8, S2, L1.8, L2/T2/SB-AGN (SB with indications of AGN activity in the literature), and SB classes have similar average X-ray spectra, but these average spectra can be distinguished from class to class. The S2 (L1.8) class is linked to the S1.8 (S1) class with a larger SB-like component than the S1.8 (S1) class. The L2, T2, and SB-AGN classes constitute a class in the X-rays similar to the S2 class, albeit with larger portions of SB-like component. We argue that this SB-like component might come from the contribution of the host galaxy emission to the X-rays, which is high when the AGN is weak. Up to 80% of the emission line nuclei and, on average, all the optical classes included in our sample show a significant fraction of S1-like or S1.8-like components. Thus, an AGN-like component seems to be present in the vast majority of the emission line nuclei in our sample. Conclusions. The ANN trained in this paper is not only useful for studying the synergies between the optical and X-ray classifications, but might also be used to infer optical properties from X-ray spectra in surveys like eRosita.

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The Central Gas Systems of Early-Type Galaxies Traced by Dust Features, Based on the [ITAL]HUBBLE SPACE TELESCOPE[/ITAL][ITAL]Hubble Space Telescope[/ITAL] WFPC2 Archival Images

Cited by 54 publications

References 15 publications

The X‐Ray–faint Emission of the Supermassive Nuclear Black Hole of IC 1459

The X‐Ray–faint Emission of the Supermassive Nuclear Black Hole of IC 1459

Deep ISOPHOT far-infrared imaging of M 86

Synapses of active galactic nuclei:

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