Mid-Infrared line diagnostics of active galaxies

Sturm, E.; Lutz, D.; Verma, Aprajita; Netzer, H.; Sternberg, A.; Moorwood, A. F. M.; Oliva, E.; Genzel, R.

doi:10.1051/0004-6361:20021043

Cited by 224 publications

(394 citation statements)

References 29 publications

(50 reference statements)

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“…Spitzer mid-IR spectroscopy is the ideal tool to search for AGNs in such galaxies. As has been shown in previous works, AGNs show prominent high-excitation fine-structure line emission, but starburst and normal galaxies are characterized by a lower excitation spectra characteristic of H ii regions ionized by young stars (e.g., Genzel et al 1998;Sturm et al 2002;Satyapal et al 2004). In particular, the [Ne v] 14 mm (ionization potential 96 eV) line is not produced in H ii regions surrounding young stars, the dominant energy source in starburst galaxies, since even hot massive stars emit very few photons with energy sufficient for the pro-L10 SATYAPAL ET AL.…”

supporting

confidence: 62%

The Discovery of an Active Galactic Nucleus in the Late-Type Galaxy NGC 3621: Spitzer Spectroscopic Observations

Satyapal

Vega

Heckman

et al. 2007

ApJ

113

139

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We report the discovery of an active galactic nucleus (AGN) in the nearby SAd galaxy NGC 3621 using Spitzer high spectral resolution observations. These observations reveal the presence of [Ne v] 14 and 24 mm emission that is centrally concentrated and peaks at the position of the near-infrared nucleus. Using the [Ne v] line luminosity, we estimate that the nuclear bolometric luminosity of the AGN is ∼ ergs s Ϫ1 , which, 41 5 # 10 based on the Eddington limit, corresponds to a lower mass limit of the black hole of ∼ M , . Using an 3 4 # 10 order-of-magnitude estimate for the bulge mass based on the Hubble type of the galaxy, we find that this lower mass limit does not put a strain on the well-known relationship between the black hole mass and the host galaxy's stellar velocity dispersion established in predominantly early-type galaxies. Multiwavelength follow-up observations of NGC 3621 are required to obtain more precise estimates of the bulge mass, black hole mass, accretion rate, and nuclear bolometric luminosity. The discovery reported here adds to the growing evidence that a black hole can form and grow in a galaxy with no or minimal bulge.

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supporting

confidence: 62%

The Discovery of an Active Galactic Nucleus in the Late-Type Galaxy NGC 3621: Spitzer Spectroscopic Observations

Satyapal

Vega

Heckman

et al. 2007

ApJ

113

139

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“…AGNs in U/LIRGs can be identified in the IR by several means: (i) with the detection of high-excitation MIR emission lines (e.g., Sturm et al 2002) Lutz et al 1999;Petric et al 2011); (iii) with the EW of the PAH features, which tend to be lower in the presence of a bright AGN, since it can destroy PAH molecules (e.g., Imanishi et al 2010b); (iv) studying the slope of the 2.5-5 μm continuum (Γ 2.5-5 , e.g., Imanishi et al 2010b) or the continuum 30 μm/15 μm flux density ratio (e.g., Stierwalt et al 2013), which tend to be red in the presence of an AGN; (v) using the depth of absorption features (e.g., Imanishi & Dudley 2000; Risaliti et al 2006;Georgantopoulos et al 2011a), with large depths pointing toward AGNs obscured by dust; and/or (vi) from deviations of the well-known correlation between the far-IR (FIR) and the radio luminosity (Helou et al 1985;Condon et al 1991;Condon 1992) using the radio-FIR flux ratio q (e.g., Yun et al 2001). We find that all these proxies ( …”

Section: Ir and X-ray Tracers Of Agn Activity In U/lirgsmentioning

confidence: 99%

NuSTAR UNVEILS A HEAVILY OBSCURED LOW-LUMINOSITY ACTIVE GALACTIC NUCLEUS IN THE LUMINOUS INFRARED GALAXY NGC 6286

Ricci

Bauer

Treister

et al. 2016

ApJ

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We report the detection of a heavily obscured active galactic nucleus (AGN) in the luminous infrared galaxy (LIRG) NGC 6286 identified in a 17.5 ks Nuclear Spectroscopic Telescope Array observation. The source is in an early merging stage and was targeted as part of our ongoing NuSTAR campaign observing local luminous and ultraluminous infrared galaxies in different merger stages. NGC 6286 is clearly detected above 10 keV and by including the quasi-simultaneous Swift/XRT and archival XMM-Newton and Chandra data, we find that the source is heavily obscured (N H ;(0.95−1.32) × 10 24 cm −2 ) with a column density consistent with being Compton-thick (CT, N log cm 24The AGN in NGC 6286 has a low absorption-corrected luminosity (L 2−10 keV ∼ 3 −20 × 10 41 erg s −1 ) and contributes 1% to the energetics of the system. Because of its low luminosity, previous observations carried out in the soft X-ray band (<10 keV) and in the infrared did not notice the presence of a buried AGN. NGC 6286 has multiwavelength characteristics typical of objects with the same infrared luminosity and in the same merger stage, which might imply that there is a significant population of obscured low-luminosity AGNs in LIRGs that can only be detected by sensitive hard X-ray observations.

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“…Genzel et al (1998) were the first to show that ionization-sensitive indices based on midinfrared ratios were helpful for identifying the nature of heavily obscured nuclear sources (Genzel et al 1998;Laurent et al 2000;Sturm et al 2002;Peeters et al 2004). We have thus taken advantage of the resolving power ( ) of the In-R ∼ 600 frared Spectrograph (IRS) on board the Spitzer Space Telescope to calculate highly accurate ionization diagnostic ratios.…”

Section: Introductionmentioning

confidence: 99%

Constraints on Accretion in Ultraluminous X-Ray Sources fromSpitzerIRS Observations of NGC 4485/4490: Infrared Diagnostic Diagrams

Vázquez¹,

Hornschemeier²,

Colbert³

et al. 2007

ApJ

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Constraining the astrophysical nature of ultraluminous X-ray (ULX) sources, which have X-ray luminosities exceeding 10 39 ergs s Ϫ1 , has been elusive due to the optical faintness of any counterparts. With high spectral resolution observations in the ∼10-30 mm wavelength range we have conducted an experiment to study six ULX sources in the NGC 4485/4490 galaxy pair. We have found that five of the six ULXs, based on mid-infrared spectral diagnostics, show the characteristic higher ionization features that are found in AGNs. The sixth source, ULX-1, is consistent with being a supernova remnant. The chief infrared spectral diagnostics used are the ratiosIn two instances fits to the continuum and polycyclic aromatic hydrocarbon (PAH) features also indicate higher dust temperatures, which are characteristic of accreting sources. Overall, however, we find that the continuum is dominated by stellar processes, and the best diagnostic features are the emission lines. High spectral resolution studies in the mid-infrared thus appear to show great promise for determining the astrophysical nature of ULXs.

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Mid-Infrared line diagnostics of active galaxies

Cited by 224 publications

References 29 publications

The Discovery of an Active Galactic Nucleus in the Late-Type Galaxy NGC 3621: Spitzer Spectroscopic Observations

The Discovery of an Active Galactic Nucleus in the Late-Type Galaxy NGC 3621: Spitzer Spectroscopic Observations

NuSTAR UNVEILS A HEAVILY OBSCURED LOW-LUMINOSITY ACTIVE GALACTIC NUCLEUS IN THE LUMINOUS INFRARED GALAXY NGC 6286

Constraints on Accretion in Ultraluminous X-Ray Sources fromSpitzerIRS Observations of NGC 4485/4490: Infrared Diagnostic Diagrams

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