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Relevant bibliographies by topics / Active Galactic Nuclei, quasars, emission lines, Seyfert

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Journal articles

Academic literature on the topic 'Active Galactic Nuclei, quasars, emission lines, Seyfert'

Author: Grafiati

Published: 10 March 2023

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Journal articles on the topic "Active Galactic Nuclei, quasars, emission lines, Seyfert"

1

Zhou, Yipeng, Lei Hao, Peng Jiang, et al. "Discovery of a Radio-loud Narrow-line Seyfert 1 Galaxy at z = 0.9 Reddened with a Strong 2175 Å Bump." Astrophysical Journal 941, no. 2 (2022): 111. http://dx.doi.org/10.3847/1538-4357/aca085.

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Abstract We present a broadband spectrophotometric analysis of an unusual quasar, SDSS J160558.86+474300.1, at z = 0.9, found in a systematic search for reddened radio-loud narrow-line Seyfert 1 galaxies (NLS1s). J1605+4743 qualifies for the conventional definition of an NLS1 in its permitted emission line widths and Hβ/[O iii] flux ratio. It also shows strong Fe ii emissions. J1605+4743 has a steep radio spectrum. With a radio loudness of ∼150 (70) before (after) reddening correction, it is among the most radio-loud NLS1s discovered. In addition, the blueshifted emission lines are also found

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2

Marziani, Paola, Marco Berton, Swayamtrupta Panda, and Edi Bon. "Optical Singly-Ionized Iron Emission in Radio-Quiet and Relativistically Jetted Active Galactic Nuclei." Universe 7, no. 12 (2021): 484. http://dx.doi.org/10.3390/universe7120484.

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The issue of the difference between optical and UV properties of radio-quiet and radio-loud (relativistically “jetted”) active galactic nuclei (AGN) is a long standing one, related to the fundamental question of why a minority of powerful AGN possess strong radio emission due to relativistic ejections. This paper examines a particular aspect: the singly-ionized iron emission in the spectral range 4400–5600 Å, where the prominent HI Hβ and [Oiii]λλ4959,5007 lines are also observed. We present a detailed comparison of the relative intensity of Feii multiplets in the spectral types of the quasar

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3

Liu, Chenxu, Karl Gebhardt, Erin Mentuch Cooper, et al. "The Active Galactic Nuclei in the Hobby–Eberly Telescope Dark Energy Experiment Survey (HETDEX). I. Sample Selection." Astrophysical Journal Supplement Series 261, no. 2 (2022): 24. http://dx.doi.org/10.3847/1538-4365/ac6ba6.

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Abstract We present the first active galactic nuclei (AGN) catalog of the Hobby–Eberly Telescope Dark Energy Experiment Survey (HETDEX) observed between 2017 January and 2020 June. HETDEX is an ongoing spectroscopic survey (3500–5500 Å) with no target preselection based on magnitudes, colors or morphologies, enabling us to select AGN based solely on their spectral features. Both luminous quasars and low-luminosity Seyferts are found in our catalog. AGN candidates are selected with at least two significant AGN emission lines, such as the Lyα and C iv λ1549 line pair, or with a single broad emis

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4

Lyu, Jianwei, and George H. Rieke. "Polar Dust Emission in Quasar IR SEDs and Its Correlation with Narrow-line Regions." Astrophysical Journal Letters 940, no. 2 (2022): L31. http://dx.doi.org/10.3847/2041-8213/ac9e5c.

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Abstract Polar dust has been found to play an important role in the mid-infrared emission of nearby Seyfert nuclei. If and how often polar dust exists among the quasar population is unknown due to the lack of spatially resolved observations. In this Letter, we report correlations between the prominence of active galactic nucleus (AGN) forbidden line emission (commonly associated with the narrow-line region) and the dust mid-IR energy output among the archetypal Palomar-Green quasar sample and other bright type-1 AGNs drawn from the Sloan Digital Sky Survey, Spitzer, and Wide-field Infrared Sur

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5

Maitra, Chandreyee, Frank Haberl, Valentin D. Ivanov, Maria-Rosa L. Cioni, and Jacco Th van Loon. "Identification of AGN in the XMM-Newton X-ray survey of the SMC." Astronomy & Astrophysics 622 (January 24, 2019): A29. http://dx.doi.org/10.1051/0004-6361/201833663.

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Context. Finding active galactic nuclei (AGN) behind the Magellanic Clouds (MCs) is difficult because of the high stellar density in these fields. Although the first AGN behind the Small Magellanic Cloud (SMC) were reported in the 1980s, it is only recently that the number of AGN known behind the SMC has increased by several orders of magnitude. Aims. The mid-infrared colour selection technique has proven to be an efficient means of identifying AGN, especially obscured sources. The X-ray regime is complementary in this regard and we use XMM-Newton observations to support the identification of

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6

Jha, Vivek Kumar, Hum Chand, Vineet Ojha, Amitesh Omar, and Shantanu Rastogi. "A comparative study of the physical properties for a representative sample of Narrow and Broad-line Seyfert galaxies." Monthly Notices of the Royal Astronomical Society 510, no. 3 (2021): 4379–93. http://dx.doi.org/10.1093/mnras/stab3700.

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ABSTRACT We present a comparative study of the physical properties of a homogeneous sample of 144 Narrow line Seyfert 1 (NLSy1) and 117 Broad-line Seyfert 1 (BLSy1) galaxies. These two samples are in a similar luminosity and redshift range and have optical spectra available in the 16th data release of Sloan Digital Sky Survey (SDSS-DR16) and X-ray spectra in either XMM-NEWTON or ROSAT. Direct correlation analysis and a principal component analysis (PCA) have been performed using ten observational and physical parameters obtained by fitting the optical spectra and the soft X-ray photon indices

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7

Filippenko, Alexei V. "Low-Luminosity Active Galactic Nuclei." Symposium - International Astronomical Union 134 (1989): 495–512. http://dx.doi.org/10.1017/s0074180900141804.

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I review the basic properties of low-luminosity active galactic nuclei (LLAGNs) — objects in which activity similar to, but intrinsically milder than, that in QSOs and luminous Seyferts is believed to be present. Until recently, most LLAGNs were first recognized as such and studied at optical wavelengths, but evidence for activity and valuable information concerning its nature are now also being obtained in many other spectral ranges. Low-ionization nuclear emission-line regions (LINERs) are the most common LLAGNs; in a large fraction of them the emission lines come from clouds of gas probably

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8

Makishima, K., N. Iyomoto, Y. Ishisaki, and Y. Terashima. "X-Ray Observations of Low-Luminosity Active Galactic Nuclei." International Astronomical Union Colloquium 159 (1997): 52–53. http://dx.doi.org/10.1017/s0252921100039610.

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AbstractThrough X-ray observations with ASCA, low-luminosity active galactic nuclei have been found in at least seven near-by spiral galaxies. Some of them exhibit very intense, and possibly broad, Fe-K emission lines. Their time variability is relatively insignificant, in contrast to lowluminosity Seyfert galaxies.

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9

Foschini, Luigi, Matthew L. Lister, Heinz Andernach, et al. "A New Sample of Gamma-Ray Emitting Jetted Active Galactic Nuclei." Universe 8, no. 11 (2022): 587. http://dx.doi.org/10.3390/universe8110587.

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We considered the fourth catalog of gamma-ray point sources produced by the Fermi Large Area Telescope (LAT) and selected only jetted active galactic nuclei (AGN) or sources with no specific classification, but with a low-frequency counterpart. Our final list is composed of 2980 gamma-ray point sources. We then searched for optical spectra in all the available literature and publicly available databases, to measure redshifts and to confirm or change the original LAT classification. Our final list of gamma-ray emitting jetted AGN is composed of BL Lac Objects (40%), flat-spectrum radio quasars

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10

Moorwood, A. F. M., and E. Oliva. "Infrared [FeII] and H2 Line Emission in Active Galactic Nuclei." Symposium - International Astronomical Union 134 (1989): 365–71. http://dx.doi.org/10.1017/s007418090014135x.

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Infrared spectra around [FeII](1.644μm), H2 (v = 1-0 S(1) at 2.121μm) and Brγ (H 7-4 at 2.167μm) have been obtained of 35 emission line nuclei whose optical spectra range from pure HII regionlike to Seyfert 1. All three emission lines have been detected in a large fraction of those nuclei exhibiting starburst activity but not in “pure” Seyferts. The highest detection frequency, however, was found for composite nuclei showing evidence for both starburst and Seyfert activity. Several arguments suggest that both the [FeII] and H2 are shock excited and could be largely attributed to supernova remn

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