The Quasar Main Sequence Explained by the Combination of Eddington Ratio, Metallicity, and Orientation

Panda, Swayamtrupta; Marziani, Paola; Czerny, B.

doi:10.3847/1538-4357/ab3292

Cited by 97 publications

(116 citation statements)

References 67 publications

(104 reference statements)

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“…where the virial factor f vir is of the order of unity and depends on the overall geometrical distribution of the BLR clouds, their kinematics as well as their line of sight emission properties, c is the velocity of light and G is the Gravitational constant. The virial factor mainly depends on the inclination i of the BLR plane with respect to the observer and the thickness of the BLR, H BLR /R BLR , and can be expressed as (Collin et al, 2006;Mejía-Restrepo et al, 2018;Panda et al, 2019), f vir = [4(sin 2 i + (H BLR /R BLR ) 2 )] −1 .…”

Section: Introductionmentioning

confidence: 99%

Current and Future Applications of Reverberation-Mapped Quasars in Cosmology

Panda

Martínez-Aldama

2019

Front. Astron. Space Sci.

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Reverberation mapping technique (RM) is an important milestone that has elevated our understanding of Active Galactic Nuclei (AGN) demographics, giving information about the kinematics and the structure of the Broad Line Region (BLR). It is based on the time-delay response between the continuum and the emission line. The time delay is directly related to the size of the BLR which in turn is related to the continuum luminosity of the source, producing the well-known Radius-Luminosity (RL) relation. The majority of the sources with RM data, have been monitored for their Hβ emission line in low redshift sources (z < 0.1), while there are some attempts using the Mg II line for higher redshift ranges. In this work, we present a recent Mg II monitoring for the quasar CTS C30.10 (z = 0.90) observed with the 10-meter Southern African Large Telescope (SALT), for which the RL scaling based on Mg II holds within measurement and time-delay uncertainties. One of the most important advantages of reverberation mapping technique is the independent determination to the distant source, and considering the large range of redshifts and luminosities found in AGNs their use in cosmological studies is promising. However, recently it has been found that highly accreting sources show the time delays shorter than expected from the RL relation. We have proposed a correction for this effect using a sample of 117 Hβ reverberating-mapped AGN with 0.02 < z < 0.9, which recovers the low scatter along with the relation. We are able to determine the cosmological constants, Ω m and Ω Λ . Despite the applied correction, the scatter is still large for being effective for cosmological applications. In the near future, Large Synoptic Survey Telescope (LSST) 1 will cover over 10 million quasars in six photometric bands during its 10-year run. We present the first step in modelling of light curves for Hβ and Mg II and discuss the quasar selection in the context of photometric reverberation mapping with LSST. With the onset of the LSST era, we expect a huge rise in the overall quasar counts and redshift range covered (z 7.0), which will provide a better constraint of AGN properties with cosmological purposes.

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Section: Introductionmentioning

confidence: 99%

Current and Future Applications of Reverberation-Mapped Quasars in Cosmology

Panda

Martínez-Aldama

2019

Front. Astron. Space Sci.

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“…Even if the optical and UV emission lines are the same, their relative intensities and profiles change in a systematic way, what has become known as the quasar main sequence (MS) [4][5][6]. The trends of the main sequence in turn provide systematic constraints on the physical conditions of the line emitting gas [7][8][9], as well as on several multifrequency properties, including radio-loudness (see [10] for a recent review). The MS has been instrumental to the interpretation of two important results.…”

Section: Quasar Spectra: Emission From Mildly Ionized Gasmentioning

confidence: 99%

“…Higher densities are needed to maintain the ionization parameter, within reasonable limits. It is now accepted that the bulk of the low ionization lines requires high column density, high particle density, low ionization degree, and high metallicity [8,9,24].…”

Section: Quasar Spectra: Emission From Mildly Ionized Gasmentioning

confidence: 99%

Broad UV Emission Lines in Type-1 Active Galactic Nuclei: A Note on Spectral Diagnostics and the Excitation Mechanism

Marziani

Olmo

Perea

et al. 2020

Atoms

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This paper reviews several basic emission properties of the UV emission lines observed in the spectra of quasars and type-1 active galactic nuclei, mainly as a function of the ionization parameter, metallicity, and density of the emitting gas. The analysis exploits a general-purpose 4D array of the photoionization simulations computed using the code CLOUDY, covering ionization parameter in the range 10−4.5–10+1.0, hydrogen density nH∼107–1014 cm−3, metallicity Z between 0.01 and 100 Z⊙, and column density in the range 1021–1023 cm−2. The focus is on the most prominent UV emission lines observed in quasar spectra, namely Nvλ1240, Siivλ1397, Oiv]λ1402, Civλ1549, Heiiλ1640, Aliiiλ1860, Siiii]λ1892, and Ciii]λ1909, and on the physical conditions under which electron-ion impact excitation is predicted to be the dominant line producer. Photoionization simulations help constrain the physical interpretation and the domain of applicability of spectral diagnostics derived from measurements of emission line ratios, reputed to be important for estimating the ionization degree, density, and metallicity of the broad line emitting gas, as well as the relative intensity ratios of the doublet or multiplet components relevant for empirical spectral modeling.

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“…Spectral types within Pop. A are due to a gradient of R FeII (Boroson & Green, 1992;Sulentic et al, 2000;Shen & Ho, 2014;Du et al, 2016;Panda et al, 2019).…”

Section: Extreme Population Amentioning

confidence: 99%

Quasar emission lines as virial luminosity estimators

Marziani¹,

Bon²,

Bon³

et al. 2020

caosp

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Quasars accreting matter at very high rates (known as extreme Population A [xA]) may provide a new class of distance indicators covering cosmic epochs from present day up to less than 1 Gyr from the Big Bang. We report on the developments of a method that is based on "virial luminosity" estimates from measurements of emission line widths of xA quasars. The approach is conceptually equivalent to the virial estimates based on early and late type galaxies. The main issues related to the cosmological application of luminosity estimates from xA quasar line widths are the identification of proper emission lines whose broadening is predominantly virial over a wide range of luminosity, and the assessment of the effect of the emitting region orientation with respect to the line of sight. We report on recent developments concerning the use of the AlIIIλ 1860 intermediate ionisation line and of the Hydrogen Balmer line Hβ as "virial broadening estimators."

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The Quasar Main Sequence Explained by the Combination of Eddington Ratio, Metallicity, and Orientation

Cited by 97 publications

References 67 publications

Current and Future Applications of Reverberation-Mapped Quasars in Cosmology

Current and Future Applications of Reverberation-Mapped Quasars in Cosmology

Broad UV Emission Lines in Type-1 Active Galactic Nuclei: A Note on Spectral Diagnostics and the Excitation Mechanism

Quasar emission lines as virial luminosity estimators

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