Testing the AGN‐Starburst Connection in Seyfert Galaxies

Ivanov, V. D.; Rieke, G. H.; Groppi, Christopher; Alonso‐Herrero, A.; Rieke, M. J.; Engelbracht, C. W.

doi:10.1086/317792

Cited by 58 publications

(112 citation statements)

References 72 publications

(63 reference statements)

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“…In Seyfert 2s, as well as in the Seyfert 1.9 NGC 2992, CO-band absorption strength is comparable to that of the template galaxies. This result suggests no strong recent star formation occurring in Seyfert 2s, and a similar conclusion was reached by Ivanov et al (2000).…”

Section: Selection Biassupporting

confidence: 84%

“…For some of our target galaxies, other recent surveys have measured a CO sp . The results from Ivanov et al (2000) are displayed in the column (5) for comparison.…”

Section: Resultsmentioning

confidence: 99%

“…Recently, even a smaller region within a 100 8 wide window centered at 2.298 m was used by Ivanov et al (2000). The CO sp indices given by Ridgway et al (1994) and Ivanov et al (2000) are claimed to be numerically equal to the CO sp index by Doyon et al (1994), while the CO sp index by Goldader et al (1995) must be multiplied by 1.39.…”

Section: Observations and Reductionsmentioning

confidence: 99%

“…For those galaxies whose redshifted 2.40 m falls within the wavelength coverage of the Gemini grism, we have measured CO sp using both wavelength regions (e.g., 2.31-2.37 and 2.31-2.40 m). In column (5), we quote the CO sp index from Ivanov et al (2000) for the galaxies present in both samples for comparison. Despite the claims by the authors above, we found that the CO sp index does depend on and tends to grow with the wavelength range used.…”

Section: Selection Biasmentioning

confidence: 99%

“…This multiple dependency of the CO band head has led some authors to claim that it is not a reliable indicator of a starburst or a young stellar population because an old stellar population with high metallicity can mimic a young stellar population (Origlia & Oliva 2000). However, in the nucleus of Seyfert galaxies, typically a bulge of a large spiral, surface gravity dominates over metallicity in the strength of the CO band (see Ivanov et al 2000 for further discussion). In the unified model of Seyfert galaxies in which the orientation relative to the line of sight is the sole determining factor, similar stellar populations would be expected, thus providing comparable CO band absorption strength in both Seyfert 1s and Seyfert 2s.…”

Section: Introductionmentioning

confidence: 99%

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Probing the Dust Obscuration in Seyfert Galaxies using Infrared Spectroscopy. II. Implication for the Unification of Seyfert Galaxies

Rhee¹,

Larkin²

2005

ApJ

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We report near-IR spectroscopic observations of 11 Seyfert galaxies (six Seyfert 1s, one Seyfert 1.9, and four Seyfert 2s) and additional galaxies (four LINERs, two H ii, and one type 2 transition) for comparison, obtained using the Gemini twin-channel near-IR camera on the Shane 3 m telescope at Lick Observatory. With the unique design of the Gemini camera, full J and K spectra were taken simultaneously through the same slit. This produced accurate line ratios of hydrogen recombination lines over a large wavelength baseline. For the Seyfert 1s ( 1.5), the line ratios of Pa /Br are not only comparable in both broad-and narrow-line regions but also consistent with case B recombination, indicating little or no reddening in both narrow-and broad-line regions. Seyfert 2 (>1.5) galaxies, however, show substantial reddening toward the narrow-line regions. We compare optical reddening data from the literature and find significant support for the dichotomy between Seyfert 1s and Seyfert 2s, at least in lowluminosity objects. Two different scenarios are explored to explain the observed difference in reddening: a difference in reddening due to an extended dusty torus under active galactic nucleus unification, and a difference due to a different grain size distribution between the two Seyfert types. We also discuss a similar potential difference found in the strength of the 9.7 m silicate line, along with a possible correlation between the narrow-line reddening and the strength of the silicate absorption line. We also analyzed CO band head absorption features longward of 2.3 m to look for nonstellar contamination and evidence of recent star formation activity. The CO band head in Seyfert 1s shows heavy contamination from nonstellar radiation, which is correlated with an H À K nuclear color excess. We confirm that the CO spectroscopic indices in both Seyfert types do not show evidence of recent star formation. Taking the nonstellar contamination into account, there is little evidence from the CO index for a difference in star formation rates in the nuclei of Seyfert 1s and Seyfert 2s in our low-luminosity sample.

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Section: Selection Biassupporting

confidence: 84%

“…For some of our target galaxies, other recent surveys have measured a CO sp . The results from Ivanov et al (2000) are displayed in the column (5) for comparison.…”

Section: Resultsmentioning

confidence: 99%

Section: Observations and Reductionsmentioning

confidence: 99%

Section: Selection Biasmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Probing the Dust Obscuration in Seyfert Galaxies using Infrared Spectroscopy. II. Implication for the Unification of Seyfert Galaxies

Rhee¹,

Larkin²

2005

ApJ

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High M/L ratios of UCDs: A variation of the IMF?

Mieske¹,

Dabringhausen²,

Kroupa³

et al. 2008

Astron Nachr

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Various studies have established that the dynamical M/L ratios of ultra-compact dwarf galaxies (UCDs) tend to be at the limit or beyond the range explicable by standard stellar populations with canonical IMF. We discuss how IMF variations may account for these high M/L ratios and how observational approaches may in the future allow to discriminate between those possibilities. We also briefly discuss the possibility of dark matter in UCDs.

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Hidden starbursts in Seyfert 1 galaxies

Rodríguez-Ardila

Viegas

2003

Monthly Notices of the Royal Astronomical Society

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We report the detection of the 3.3‐μm polycyclic aromatic hydrocarbon (PAH) feature in two Seyfert 1 galaxies (NGC 3227 and Mrk 766) and one QSO (Mrk 478), observed with SpeX at the Infrared Telescope Facility at a spectral resolution not previously attained for these types of objects. Except for NGC 3227, this is the first time that the 3.3‐μm PAH emission has been detected in Mrk 766 and 478. The widths of the emission, reported also for the first time, are rather similar, ranging from 450 to 550 Å. The luminosity of the 3.3‐μm PAH emission measured in the QSO Mrk 478 places it at a level similar to that found in starburst and infrared‐luminous galaxies, and implies that this object is having a vigorous burst of star formation. The spatial resolution of the spectra allows us to constrain the location of the star‐forming region to the inner 1 kpc for the QSO and 150 pc for the Seyferts. Our results support the idea that these objects reside in molecular gas‐rich galaxies and that their observed infrared excess is primarily due to star formation, as previously indicated by CO and H2 observations. We also report, for Mrk 1239, the presence of a broad emission feature centred at 3.43 μm, not previously detected in an extragalactic object and the origin of which is not yet clear.

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Testing the AGN‐Starburst Connection in Seyfert Galaxies

Cited by 58 publications

References 72 publications

Probing the Dust Obscuration in Seyfert Galaxies using Infrared Spectroscopy. II. Implication for the Unification of Seyfert Galaxies

Probing the Dust Obscuration in Seyfert Galaxies using Infrared Spectroscopy. II. Implication for the Unification of Seyfert Galaxies

High M/L ratios of UCDs: A variation of the IMF?

Hidden starbursts in Seyfert 1 galaxies

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