The quasar main sequence and its potential for cosmology
P. Marziani, D. Dultzin, A. Del Olmo, M. D'Onofrio, J. A. de Diego, G. M. Stirpe, E. Bon, N. Bon, B. Czerny, J. Perea, S. Panda, M. L. Martinez-Aldama, C. A. Negrete
备注：
5 pages, 2 figures, contribution presented at the IAU Symposium 356, Nuclear Activity in Galaxies Across Cosmic Time, held in Addis Ababa, Ethiopia, on Oct. 7-11, 2019. M. Povic et al. (Eds.)
The main sequence offers a method for the systematization of quasar spectral properties. Extreme FeII emitters (or extreme Population A, xA) are believed to be sources accreting matter at very high rates. They are easily identifiable along the quasar main sequence, in large spectroscopic surveys over a broad redshift range. The very high accretion rate makes it possible that massive black holes hosted in xA quasars radiate at a stable, extreme luminosity-to-mass ratio. After reviewing the basic interpretation of the main sequence, we report on the possibility of identifying virial broadening estimators from low-ionization line widths, and provide evidence of the conceptual validity of redshift-independent luminosities based on virial broadening for a known luminosity-to-mass ratio.
We present a novel, purely geometric probe of cosmology based on measurements of differential time delays between images of strongly lensed quasars due to finite source effects. Our approach is solely dependent on cosmology via a ratio of angular diameter distances, the image separation, and the source size. It thereby entirely avoids the challenges of lens modelling that conventionally limit time delay cosmography, and instead entails the lensed reverberation mapping of the quasar Broad Line Region. We demonstrate that differential time delays are measurable with short cadence spectroscopic m…
Quasars accreting matter at very high rates (known as extreme Population A [xA] or super-Eddington accreting massive black holes) provide a new class of distance indicators covering cosmic epochs from the present-day Universe up to less than 1 Gyr from the Big Bang. The very high accretion rate makes it possible that massive black holes hosted in xA quasars radiate at a stable, extreme luminosity-to-mass ratio. This in turns translates into stable physical and dynamical conditions of the mildly ionized gas in the quasar low-ionization line emitting region. In this contribution, we analyze the …
Last year (2013) was more or less the 50th anniversary of the discovery of quasars. It is an interesting time to review what we know (and don't know) about them both empirically and theoretically. These compact sources involving line emitting plasma show extraordinary luminosities extending to one thousand times that of our Milky Way in emitting volumes of a few solar system diameters (bolometric luminosity log L$_{bol} \sim $ 44-48 [erg s$^{-1}$]: D=1-3 light months $\sim$ $10^3$ - $10^4$ gravitational radii). The advent of 8-10 meter class telescopes enables us to study them spectroscopicall…
Quasars accreting matter at very high rates (known as extreme Population A [xA] quasars, possibly associated with super-Eddington accreting massive black holes) may provide a new class of distance indicators covering cosmic epochs from present day up to less than 1 Gyr from the Big Bang. At a more fundamental level, xA quasars are of special interest in studies of the physics of AGNs and host galaxy evolution. However, their observational properties are largely unknown. xA quasars can be identified in relatively large numbers from major optical surveys over a broad range of redshifts, thanks t…
This study is focused on the observational measurement of the viewing angle of individual quasars by modeling the broadband quasar spectrum ranging from the infra-red (IR) to the soft X-ray band. Sources are selected from various published catalogs, and their broadband quasi-simultaneous spectral data points were collected and used to model. We started with a COSMOS sample of type-1 sources which have broadband photometric points. Then, to include more data points, we cross-matched the COSMOS with the SDSS DR14 quasar catalog, and eventually, we find 90 sources that have broadband data ranging…
The symmetry axes of active galactic nuclei (AGN) are randomly distributed in space but highly inclined sources are heavily obscured and are not seen as quasars with broad emission lines. The obscuring torus geometry determines the average viewing angle, and if the torus geometry changes with the redshift, this average viewing angle will also change. Thus the ratio between the isotropic luminosity and observed luminosity may change systematically with redshift. Therefore, if we use quasars to measure the luminosity distance by evaluating the isotropic absolute luminosity and measuring the obse…
As Setti & Woltjer noted back in 1973, quasars could be used to construct the Hubble diagram but the actual application was not that straightforward. It took years to implement the idea successfully. Most of the ways to use quasars for cosmology now require an advanced understanding of their structure, step by step. We briefly review this progress, with unavoidable personal bias, and concentrate on bright unobscured sources. We will mention the problem of the gas flow character close to the innermost stable circular orbit close to the black hole, discussed 50 years ago, which later led to the …
We propose a method to identify quasars radiating closest to the Eddington limit, defining primary and secondary selection criteria in the optical, UV and X-ray spectral range based on the 4D eigenvector 1 formalism. We then show that it is possible to derive a redshift-independent estimate of luminosity for extreme Eddington ratio sources. Using preliminary samples of these sources in three redshift intervals (as well as two mock samples), we test a range of cosmological models. Results are consistent with concordance cosmology but the data are insufficient for deriving strong constraints. Mo…
The last few years have seen the confirmation of several trends associated with the quasar main sequence. The idea of a main sequence for quasars is relatively recent, and its full potential for the observational classification and contextualization of quasar properties has yet to be fully exploited. The main sequence drivers are discussed in terms of the properties of extreme objects. We briefly summarize developments that constrain the viewing angle of the accretion disk in a particular class of quasars (extreme Population B, radiating at low Eddington ratio), as well as inferences on the ch…
Reverberation mapping technique is an important milestone in AGN demographics, kinematics and the structure of the Broad Line Region (BLR) based on the time-delay response between the continuum and emission line. The time delay is directly related to the size of BLR which is related to the continuum luminosity of the source, producing the well-known Radius-Luminosity (RL) relation. The majority of sources have been monitored for their H$β$ emission line in low redshift sources ($z<0.1$), while there are some attempts using the MgII line for higher redshifts. We present a recent MgII monitoring…
The relation between star formation rates and stellar masses, i.e. the galaxy main sequence, is a useful diagnostic of galaxy evolution. We present the distributions relative to the main sequence of 55 optically-selected PG and 12 near-IR-selected 2MASS quasars at z <= 0.5. We estimate the quasar host stellar masses from Hubble Space Telescope or ground-based AO photometry, and the star formation rates through the mid-infrared aromatic features and far-IR photometry. We find that PG quasar hosts more or less follow the main sequence defined by normal star-forming galaxies while 2MASS quasar ho…
The diverse properties of broad-line quasars appear to follow a well-defined main sequence along which the optical FeII strength increases. It has been suggested that this sequence is mainly driven by the Eddington ratio (L/L_Edd) of the black hole (BH) accretion. Shen & Ho demonstrated with quasar clustering analysis that the average BH mass decreases with increasing FeII strength when quasar luminosity is fixed, consistent with this suggestion. Here we perform an independent test by measuring the stellar velocity dispersion sigma* (hence the BH mass via the M-sigma* relation) from decomposed…
The last 25 years saw a major step forward in the analysis of optical and UV spectroscopic data of large quasar samples. Multivariate statistical approaches have led to the definition of systematic trends in observational properties that are the basis of physical and dynamical modeling of quasar structure. We discuss the empirical correlates of the so-called "main sequence" associated with the quasar Eigenvector 1, its governing physical parameters and several implications on our view of the quasar structure, as well as some luminosity effects associated with the virialized component of the li…
We analyze the optical properties of Radio-Loud quasars along the Main Sequence (MS) of quasars. A sample of 355 quasars selected on the basis of radio detection was obtained by cross-matching the FIRST survey at 20cm and the SDSS DR12 spectroscopic survey. We consider the nature of powerful emission at the high-FeII end of the MS. At variance with the classical radio-loud sources which are located in the Population B domain of the MS optical plane, we found evidence indicating a thermal origin of the radio emission of the highly accreting quasars of Population A.
Using the six years of the spectroscopic monitoring of the luminous quasar HE 0435-4312 ($z=1.2231$) with the Southern African Large Telescope (SALT), in combination with the photometric data (CATALINA, OGLE, SALTICAM, and BMT), we determined the rest-frame time-delay of $296^{+13}_{-14}$ days between the MgII broad-line emission and the ionizing continuum using seven different time-delay inference methods. Artefact time-delay peaks and aliases were mitigated using the bootstrap method, prior weighting probability function as well as by analyzing unevenly sampled mock light curves. The MgII em…
A quasar main sequence is widely believed to reveal itself through objects represented in a plane spanned by two parameters: the full-width at half-maximum (FWHM) of H$β$, and the ratio of Fe II to H$β$ equivalent width. This sequence is related to the application to quasar properties of principal component analysis (PCA), which reveals that the main axis of variance (Eigenvector 1) is co-directional with a strong anti-correlation between these two measurements. We aim to determine whether the dominance of two Eigenvectors, originally discovered over two decades ago, is replicated in newer hig…
The discovery of quasar J1342+0928 (z=7.54) reinforces the time compression problem associated with the premature formation of structure in LCDM. Adopting the Planck parameters, we see this quasar barely 690 Myr after the big bang, no more than several hundred Myr after the transition from Pop III to Pop II star formation. Yet conventional astrophysics would tell us that a 10 solar-mass seed, created by a Pop II/III supernova, should have taken at least 820 Myr to grow via Eddington-limited accretion. This failure by LCDM constitutes one of its most serious challenges, requiring exotic `fixes'…
We address the effect of orientation of the accretion disk plane and the geometry of the broad-line region (BLR) as part of an effort to understand the distribution of quasars in the optical plane of the quasar main sequence. We utilize the photoionization code CLOUDY to model the BLR incorporating the grossly underestimated form factor ($f$). Treating the aspect of viewing angle appropriately, we confirm the dependence of the $R_{\mathrm{FeII}}$ sequence on Eddington ratio and on the related observational trends - as a function of the SED shape, cloud density and composition, verified from pr…
Using 16,421 spectra from a sample of 340 quasars ($1.62<z<3.30$) from the SDSS Reverberation Mapping Project, we present an analysis of quasar spectral variability. We confirm the intrinsic Baldwin Effect and brighter-means-bluer trends in which emission line strength and color are associated with changes in luminosity. We then create a composite differential spectrum that captures the wavelength dependence of quasar variability as a function of change in luminosity. When using a bandpass around 1740 Å to describe the luminosity, the differential spectrum follows a power law at longer wavelen…
Because follow-up observations of quadruple gravitational lens systems are of extraordinary importance for astrophysics and cosmology, we present single-epoch optical spectra and $r$--band light curves of PS J0147+4630. This recently discovered system mainly consists of four images ABCD of a background quasar around a foreground galaxy G that acts as a gravitational lens. First, we use long--slit spectroscopic data in the Gemini Observatory Archive and a multi-component fitting to accurately resolve the spectra of A, D, and G. The spectral profile of G resembles that of an early-type galaxy at…
We address the effect of the viewing angle of the accretion disk plane and the geometry of the broad-line region (BLR) with the goal of interpreting the distribution of quasars along the main sequence (MS). We utilize photoionization code CLOUDY to model the BLR FeII emission, incorporating the grossly underestimated role of the form factor (f). We recover the dependence of the strength of the FeII emission in the optical (R$_{\rm{FeII}}$) on L$_{\rm{bol}}$/L$_{\rm{Edd}}$ ratio and related observational trends - as a function of the spectral energy distribution (SED) shape, cloud density, comp…
A tight non-linear relation between the X-ray and the optical-ultraviolet (UV) emission has been observed in Active Galactic Nuclei (AGN) over a wide range of redshift and several orders of magnitude in luminosity, suggesting the existence of an ubiquitous physical mechanism regulating the energy transfer between the accretion disc and the X-ray emitting corona. Recently, our group developed a method to use this relation in the observational cosmology, turning quasars into standardizable candles. This work has the main aim to investigate the potential evolution of this correction at high redsh…
The luminosity function for quasars (QSOs) is usually fitted by a Schechter function. The dependence of the number of quasars on the redshift, both in the low and high luminosity regions, requires the inclusion of a lower and upper boundary in the Schechter function. The normalization of the truncated Schechter function is forced to be the same as that for the Schechter function, and an analytical form for the average value is derived. Three astrophysical applications for QSOs are provided: deduction of the parameters at low redshifts, behavior of the average absolute magnitude at high redshif…
We explore the evolution of the time variability (in the optical $g$-band and on timescales of weeks to years) of SDSS Stripe 82 quasars along the quasar main sequence. A parent sample of $1004$ quasars within $0.5\leq z \leq 0.89$ are used for our statistical studies, we then make subsamples from our parent sample: a subsample of $246$ quasars with similar luminosities, and a subsample of $399$ quasars with similar Rfe (i.e., the ratio of the equivalent width of FeII within $4435$--$4685\ \mathrmÅ$ to that of \Hbeta). We find the variability amplitude decreases with luminosity ($L_{\mathrm{bo…
Mapping the Quasar Main Sequence in the UV range: A Connection with the UV Fe III Emission
Universidad Nacional Autónoma de México（墨西哥国立自治大学）；Universidad de Concepción（康塞普西翁大学）；Millennium Institute of Astrophysics (MAS)（天体物理学千年研究所）；University of Utah（犹他大学）；National Institute for Astrophysics (INAF), Astronomical Observatory of Padua（国家天体物理研究所帕多瓦天文台）；Instituto de Astrofísica de Andalucía (IAA–CSIC)（安达卢西亚天体物理研究所）；International Gemini Observatory/NSF NOIRLab（国际吉米尼观测站/美国国家光学红外天文研究实验室）
本研究利用紫外 1900 混合发射及 Fe III/Fe II 发射构建类星体主序的紫外对应平面，验证其可区分不同族群并识别高吸积 xA 源，为高红移研究提供新途径。
Narrow-line Seyfert 1 galaxies are defined on the basis of their line widths, and they are generally considered to be high Eddington ratio sources. But in the context of the Quasar Main Sequence, high Eddington rate sources are those which have weak [O III] lines and strong Fe II lines. There is an overlap between the two populations, but they are not identical. Thus these two selection criteria give a different view on which objects are actually high Eddington ratio sources. We discuss this issue in the context of the broad band spectral energy density, emission line shape modeling, Fe II pse…
Following the established view of the AGNs inner workings, an AGN is radio-loud (RL) if associated with relativistic ejections emitting a radio synchrotron spectrum (i.e., a jetted AGN). If large samples of optically-selected quasars are considered, AGNs are identified as RL if their Kellermann's radio loudness ratio RK > 10. Our aims are to characterize the optical properties of different classes based on radio-loudness within the quasar main sequence (MS) and to test whether the condition RK > 10 is sufficient for the identification of RL AGNs. A sample of 355 quasars was selected by cross-c…
Optical and UV properties of radio-quiet (RQ) and radio-loud (RL, relativistically "jetted") active galactic nuclei (AGN) are known to differ markedly; however, it is still unclear what is due to a sample selection and what is associated with intrinsic differences in the inner workings of their emitting regions. Chemical composition is an important parameter related to the trends of the quasar main sequence. Recent works suggest that in addition to physical properties such as density, column density, and ionization level, strong FeII emitters require very high metal content. Little is known, h…
In this paper we study the universality of the results of SQUEzE, a software package to classify quasar spectra and estimate their redshifts. The code is presented in \cite{Perez-Rafols+2019}. We test the results against changes on signal-to-noise, spectral resolution, wavelength coverage, and quasar brightness. We find that SQUEzE levels of performance (quantified with purity and completeness) are stable to spectra that have a noise dispersion 4 times that of our standard test sample, BOSS. We also find that the performance remains unchanged if pixels of width 25Åare considered, and decreases…
We aim to evaluate the behaviour of our 22 high-redshift (2.2 < z < 3.7) and high-luminosity (47.39 < Lbol < 48.36) quasars in the context of the 4-Dimensional Eigenvector 1. Our approach involves studying quasar physics through spectroscopic exploration of UV and optical emission line diagnostics. We are using new observations from ISAAC/VLT and mainly from the SDSS to cover the optical and the UV rest-frames, respectively. Emission lines are characterised both through a quantitative parametrisation of the line profiles, and by decomposing the emission line profiles using multicomponent fitti…
The most highly accreting quasars (xA) are of special interest in studies of the physics of AGNs and host galaxy evolution. Quasars accreting at high rates (L/LEdd $\sim$ 1) hold promise for use as 'standard candles': distance indicators detectable at very high redshift. However, their observational properties are largely unknown. A large sample of xA can clarify the main properties of quasars radiating near L/LEdd $\sim$ 1 in the Hb spectral range for redshift $\lt$ 0.8. We use selection criteria derived from 4DE1 studies to identify and analyze spectra for a sample of 334 candidate sources i…
Much effort has been done in order to better understand the active galactic nuclei mechanisms behind the relativistic jets observed in radio-loud sources. These phenomena are commonly seen in luminous objects with intermediate/high redshift such as quasars, so that the analysis of the spectroscopic properties of these sources may be a way to clarify this issue. Measurements are presented and contextualized taking advantage of the set of correlations associated with the quasar Main Sequence (MS), a parameter space that allows to connect observed properties to the relative relevance of radiative…
We present SQUEzE, a software package to classify quasar spectra and estimate their redshifts. SQUEzE is a random forest classifier operating on the parameters of candidate emission peaks identified in the spectra. We test the performance of the algorithm using visually inspected data from BOSS as a truth table. Only 4\% of the sample ($\sim$6,800 quasars and $\sim$11,520 contaminants) is needed for converged training in recommended choices of the confidence threshold ($0.2<p_{\rm min}<0.7$). For an operational mode which balances purity and completeness ($p_{\rm min}=0.28$) we recover a purit…
This program is part of QUEST (Quasar/ULIRG Evolutionary Study) and seeks to examine the gaseous environments of z < 0.3 quasars and ULIRGs as a function of host galaxy properties and age across the merger sequence from ULIRGs to quasars. This first paper in the series focuses on 33 quasars from the QUEST sample and on the kinematics of the highly ionized gas phase traced by the N V 1238, 1243 A and O VI 1032, 1038 A absorption lines in high-quality Hubble Space Telescope (HST) Cosmic Origins Spectrograph (COS) data. N V and O VI outflows are present in about 60% of the QUEST quasars and span …
We offer a broad review of Balmer line phenomenology in type 1 active galactic nuclei, briefly sum- marising luminosity and radio loudness effects, and discussing interpretation in terms of nebular physics along the 4D eigenvector 1 sequence of quasars. We stress that relatively rare, peculiar Balmer line profiles (i.e., with large shifts with respect to the rest frame or double and multiple peaked) that start attracted attentions since the 1970s are still passable of multiple dynamical interpretation. More mainstream objects are still not fully understood as well, since competing dynamical mo…
Broad emission lines in quasars enable us to "resolve" structure and kinematics of the broad line emitting region (BLR) thought to in- volve an accretion disk feeding a supermassive black hole. Interpretation of broad line measures within the 4DE1 formalism simplifies the apparent confusion among such data by contrasting and unifying properties of so-called high and low accreting Population A and B sources. Hβ serves as an estimator of black hole mass, Eddington ratio and source rest frame, the latter a valuable input for Civλ1549 studies which allow us to isolate the blueshifted wind componen…
Eigenvector 1 (EV1) was found to be the dominant component behind the significant correlations for the measured parameters in quasar spectra (Boroson & Green, 1992). The parameter R$_{\mathrm{FeII}}$, which strongly correlates to the EV1, is the ${\mathrm{FeII}}$ strength, defined to be the ratio of the equivalent width of ${\mathrm{FeII}}$ to the equivalent width of ${\mathrm{Hβ}}$. This allows to construct a quasar main sequence analogous to the stellar properties driven HR diagram (Sulentic et al. 2001). We try to find the main driver behind the EV1 among the basic (theoretically motivated)…
Hot, Photoionized X-ray Gas in Two Luminous Type 2 Quasars: Chandra-HST Evidence for a Wind-Driven Sequence
NASA Goddard Space Flight Center（NASA戈达德太空飞行中心）；The Catholic University of America（天主教大学）；Harvard-Smithsonian Center for Astrophysics（哈佛-史密森天体物理中心）；INAF Osservatorio Astronomico di Roma（意大利国家天体物理研究所罗马天文台）；Eureka Scientific, Inc.（尤里卡科学公司）；INAF - Osservatorio Astronomico di Brera（意大利国家天体物理研究所布雷拉天文台）；Dipartimento di Fisica, Università di Trento（特伦托大学物理系）；Naval Research Laboratory（海军研究实验室）；AURA for ESA（欧洲空间局美国天文研究联盟）
Quasars are among the most luminous sources characterized by their broad band spectra ranging from radio through optical to X-ray band, with numerous emission and absorption features. Using the Principal Component Analysis (PCA), Boroson & Green (1992) were able to show significant correlations between the measured parameters. Among the significant correlations projected, the leading component, related to Eigenvector 1 (EV1) was dominated by the anti-correlation between the Fe${\mathrm{II}}$ optical emission and [OIII] line where the EV1 alone contained 30% of the total variance. This introduc…
Quasars are complex sources, characterized by broad band spectra from radio through optical to X-ray band, with numerous emission and absorption features. However, Boroson & Green (1992) used Principal Component Analysis (PCA), and with this analysis they were able to show significant correlations between the measured parameters. The leading component, related to Eigenvector 1 (EV1) was dominated by the anticorrelation between the Fe${\mathrm{II}}$ optical emission and [OIII] line and EV1 alone contained 30% of the total variance. It opened a way in defining a quasar main sequence, in close an…
We present an analysis of UV spectra of 13 quasars believed to belong to extreme Population A (xA) quasars, aimed at the estimation of the chemical abundances of the broad line emitting gas. Metallicity estimates for the broad line emitting gas of quasars are subject to a number of caveats, although present data suggest the possibility of an increase along the quasar main sequence along with prominence of optical Fe II emission. Extreme Population A sources with the strongest Fe II emission offer several advantages with respect to the quasar general population, as their optical and UV emission…
