X-Ray Emission of Active Galactic Nuclei with Circumnuclear Star-forming Rings: NGC 1097 and NGC 7469

ABSTRACT We analyse different photometric and spectroscopic properties of active galactic nuclei (AGNs) and quasars (QSOs) selected by their mid-IR power-law and X-ray emission from the COSMOS survey. We use a set of star-forming galaxies as a control sample to compare with the results. We have considered samples of obscured (HR > −0.2) and unobscured (HR < −0.2) sources including AGNs with LX < 1044 erg s−1, as well as QSOs (LX > 1044 erg s−1) with 1.4 ≤ z ≤ 2.5. We also study the typical environment of these samples, by assessing neighbouring galaxy number density and neighbour properties such as colour, stellar mass, and star formation rate. We find that the UV/optical and mid-infrared colour distribution of the different AGN types differ significantly. Also, we obtain most of AGNs and QSOs to be more compact when compared to the sample of SF galaxies. In general we find that the stellar mass distribution of the different AGN sample are similar, obtaining only a difference of $\Delta \overline{\mathrm{log}M}=0.3$ dex (M⊙) between unobscured and obscured QSOs. Obscured and unobscured AGNs and QSOs reside in different local environment at small (rp < 100 kpc) scales. Our results support previous findings where AGN type correlates with environment. These differences and those found in AGN host properties cast out the simplest unified model in which obscuration is purely an orientation effect.

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The X-Ray Background from Star-Forming Galaxies

Symposium - International Astronomical Union ◽

10.1017/s0074180900241156 ◽

1990 ◽

Vol 139 ◽

pp. 412-413

Author(s):

Richard E. Griffiths

Keyword(s):

Energy Range ◽

Active Galactic Nuclei ◽

Surface Density ◽

Galactic Nuclei ◽

X Ray ◽

Star Forming ◽

Smooth Component ◽

Spatial Fluctuations ◽

Deep Survey ◽

X Ray Background

It has been established observationally that at least 30% of the all-sky X-ray background (XRB) in the energy range of 1–3 keV comes from active galactic nuclei (AGN) in the redshift interval of 0.4 to 1.2 (Griffiths et al. 1983, 1988); it is also quite plausible that AGN contribute half of the XRB in the 1–3 keV range (Morisawa and Takahara 1989). However, analysis of spatial fluctuations in the Einstein deep survey counts (Hamilton and Helfand 1987; Barcons and Fabian 1989) has indicated the presence of a relatively smooth component of the XRB with a corresponding surface density of discrete sources of at least several thousand per square degree.

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X-rays from Green Pea analogues

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stx1286 ◽

2017 ◽

Vol 470 (1) ◽

pp. 606-611 ◽

Cited By ~ 5

Author(s):

M. Brorby ◽

P. Kaaret

Keyword(s):

Star Formation ◽

Active Galactic Nuclei ◽

Formation Rate ◽

Galactic Nuclei ◽

High Mass ◽

X Rays ◽

X Ray ◽

Star Forming ◽

Green Pea ◽

X Ray Binaries

Abstract X-ray observations of two metal-deficient luminous compact galaxies (LCG; SHOC 486 and SDSS J084220.94+115000.2) with properties similar to the so-called Green Pea galaxies were obtained using the Chandra X-ray Observatory. Green Pea galaxies are relatively small, compact (a few kpc across) galaxies that get their green colour from strong [O iii] λ5007 Å emission, an indicator of intense, recent star formation. These two galaxies were predicted to have the highest observed count rates, using the X-ray luminosity–star formation rate (LX–SFR) relation for X-ray binaries, from a statistically complete sample drawn from optical criteria. We determine the X-ray luminosity relative to SFR and metallicity for these two galaxies. Neither exhibits any evidence of active galactic nuclei, and we suspect that the X-ray emission originates from unresolved populations of high-mass X-ray binaries. We discuss the LX–SFR–metallicity plane for star-forming galaxies and show that the two LCGs are consistent with the prediction of this relation. This is the first detection of Green Pea analogues in X-rays.

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Circumnuclear multi-phase gas around nearby AGNs investigated by ALMA

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320002148 ◽

2019 ◽

Vol 15 (S359) ◽

pp. 436-437

Author(s):

Takuma Izumi

Keyword(s):

Active Galactic Nuclei ◽

Galactic Nuclei ◽

Seyfert Galaxy ◽

Physical Origin ◽

X Ray ◽

Physical Chemical ◽

Circumnuclear Disk ◽

Multi Phase ◽

Ngc 7469 ◽

Chemical Influence

AbstractSince the advent of the Atacama Large Millimeter/submillimeter Array (ALMA), more attention has been paid on the ≲100 pc scale circumnuclear disk (CND) to reveal feeding and feedback processes of active galactic nuclei (AGNs). By using cold molecular CO and atomic C0 emission line observations, we have revealed that there are multi-component gas dynamical flows around the AGN of the Circinus galaxy, which may explain the physical origin of the AGN torus. In the luminous Seyfert galaxy NGC 7469, we found that [CI](1–0) line is extraordinary bright relative to CO lines (for example J 2−1), manifesting the physical/chemical influence of the AGN on the surrounding gas in the form of X-ray dominated region (XDR).

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Forward modelling the multiwavelength properties of active galactic nuclei: application to X-ray and WISE mid-infrared samples

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2528 ◽

2020 ◽

Vol 499 (1) ◽

pp. 710-729

Author(s):

Antonis Georgakakis ◽

Angel Ruiz ◽

Stephanie M LaMassa

Keyword(s):

Active Galactic Nuclei ◽

Galactic Nuclei ◽

Spectral Energy ◽

Electromagnetic Spectrum ◽

Forward Modelling ◽

Sharp Drop ◽

Mid Infrared ◽

X Ray ◽

Star Forming ◽

Modelling Framework

ABSTRACT An empirical forward-modelling framework is developed to interpret the multiwavelength properties of active galactic nuclei (AGNs) and provide insights into the overlap and incompleteness of samples selected at different parts of the electromagnetic spectrum. The core of the model are observationally derived probabilites on the occupation of galaxies by X-ray-selected AGN. These are used to seed mock galaxies drawn from stellar-mass functions with accretion events and then associate them with spectral energy distributions that describe both the stellar and AGN emission components. This approach is used to study the complementarity between X-ray and WISE mid-infrared AGN selection methods. We first show that the basic observational properties of the X-ray and WISE AGN (magnitude and redshift distributions) are adequately reproduced by the model. We then infer the level of contamination of the WISE selection and show that this is dominated by non-AGN at redshifts z < 0.5. These are star-forming galaxies that scatter into the WISE AGN selection wedge because of photometric uncertainties affecting their colours. Our baseline model shows a sharp drop in the number density of heavily obscured AGN above the Compton-thick limit in the WISE bands. The model also overpredicts by a factor of 1.5 the fraction of X-ray associations in the WISE AGN selection box compared to observations. This suggests a population of X-ray faint sources that is not reproduced by the model. This discrepancy is discussed in the context of either heavily obscured or intrinsically X-ray weak AGN. Evidence is found in favour of the latter.

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Infrared Contributions of X-Ray Selected Active Galactic Nuclei in Dusty Star-forming Galaxies

The Astrophysical Journal ◽

10.3847/1538-4357/aaf73b ◽

2019 ◽

Vol 871 (1) ◽

pp. 87 ◽

Cited By ~ 6

Author(s):

Arianna Brown ◽

Hooshang Nayyeri ◽

Asantha Cooray ◽

Jingzhe Ma ◽

Ryan C. Hickox ◽

...

Keyword(s):

Active Galactic Nuclei ◽

Galactic Nuclei ◽

X Ray ◽

Star Forming

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Pumping of H2O Megamasers

Highlights of Astronomy ◽

10.1017/s1539299600019298 ◽

1998 ◽

Vol 11 (2) ◽

pp. 960-963

Author(s):

Moshe Elitzur

Keyword(s):

Active Galactic Nuclei ◽

Galactic Nuclei ◽

Broad Line ◽

X Ray ◽

Star Forming ◽

Broad Line Region ◽

Star Forming Regions ◽

Disk Rotation ◽

Line Region ◽

Pump Mechanism

AbstractStrong H2O maser emission is detected from active galactic nuclei (AGN) as well as Galactic objects such as star-forming regions and late-type stars. In spite of the widely different luminosities of the different masers, a common pump mechanism seems adequate: neutral collisions at densities of ˜ 108-1010 cm-3 and temperatures of ˜ 250-500 K. The different properties of the various masers can be attributed to geometry. Although disk rotation controls the AGN maser geometry it does not directly determine the dimensions. X-ray radiation and spiral shocks have been suggested as the heating sources of H2O megamasers. Both are capable of explaining the observations, and the radiative scenario seems best understood in terms of chance alignment of standard broad-line-region clouds. It is not yet clear whether these different proposals produce distinct maser signatures.

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