Search

We present photometric selection of type 1 quasars in the ≈5.3 deg2 XMM-Large Scale Structure survey field with machine learning. We constructed our training and blind-test samples using spectroscopically identified Sloan Digital Sky Survey quasars, galaxies, and stars. We utilized the XGBoost machine learning method to select a total of 1591 quasars. We assessed the classification performance based on the blind-test sample, and the outcome was favorable, demonstrating high reliability (≈99.9%) and good completeness (≈87.5%). We used XGBoost to estimate photometric redshifts of our selected quasars. The estimated photometric redshifts span a range from 0.41 to 3.75. The outlier fraction of these photometric redshift estimates is ≈17%, and the normalized median absolute deviation (σ NMAD) is ≈0.07. To study the quasar disk–corona connection, we constructed a subsample of 1016 quasars with Hyper Suprime-Cam i < 22.5 after excluding radio-loud and potentially X-ray-absorbed quasars. The relation between the optical-to-X-ray power-law slope parameter (α OX) and the 2500 Å monochromatic luminosity (L 2500Å) for this subsample is α OX = (− 0.156 ± 0.007) log L 2500 Å + (3.175 ± 0.211) with a dispersion of 0.159. We found this correlation in good agreement with the correlations in previous studies. We explored several factors, which may bias the α OX– L 2500Å relation, and found that their effects are not significant. We discussed possible evolution of the α OX– L 2500Å relation with respect to L 2500Å or redshift. [ABSTRACT FROM AUTHOR]

We develop a simple method to search for changing-look (CL) active galactic nucleus (AGN) candidates, and conduct a test run. In this method, optical variations of AGNs are monitored and CL-AGNs may appear to have a pattern of being bluer when in brightening flare-like events. Applying this method, previously classified type 2 AGNs that show the bluer-when-brighter (BWB) pattern are selected. Among more than ten thousands type 2 AGNs classified in the Sloan Digital Sky Survey (SDSS), we find 73 candidates with possibly the strongest BWB pattern. We note that 13 of them have previously been reported as CL-AGNs. We have observed nine candidates, and found that five among them showed the CL transition from type 2 to type 1. In addition, we also test extending the selection to previously classified type 1 AGNs in the SDSS by finding sources with a possible redder-when-brighter pattern, but none of the three sources observed by us is found to show the transition from type 1 to type 2. We discuss the variation properties in both the success and failure cases, and plan to observe more candidates selected with the method. From the observational results, a detailed comparison between the CL-AGNs and none CL-AGNs will help quantitatively refine the selection criteria and in turn allow us to configure the general properties of CLAGNs. [ABSTRACT FROM AUTHOR]

S-shaped radio galaxy jets are prime sources for investigating the dynamic interplay between the central active galactic nucleus (AGN), the jets, and the ambient intergalactic medium. These sources are excellent candidates for studying jet precession, as their S-shaped inversion symmetry strongly indicates underlying precession. We present a multiwavelength analysis of the giant inversion-symmetric S-shaped radio galaxy PKS 2300 |$-$| 18, which spans 0.76 Mpc. The host is a quasar at a redshift of 0.128, displaying disturbed optical morphology due to an ongoing merger with a companion galaxy. We conducted a broad-band radio spectral study using multifrequency data ranging from 183 MHz to 6 GHz, incorporating dedicated observations with the upgraded Giant Metrewave Radio Telescope (uGMRT) and Karl G. Jansky Very Large Array (JVLA) alongside archival radio data. A particle injection model was fitted to the spectra of different regions of the source to perform ageing analysis, which was supplemented with a kinematic jet precession model. The ageing analysis revealed a maximum plasma age of |$\sim$| 40 Myr, while the jet precession model indicated a precession period of |$\sim$| 12 Myr. ROentgen SATellite (ROSAT) data revealed an X-ray halo of Mpc size, and from Chandra the AGN X-ray spectrum was modelled using thermal and power-law components. The optical spectrum displaying double-peaked broad emission lines was modelled, indicating complex broad-line region kinematics at the centre with the possibility of a binary SMBH. We present the results of our multiwavelength analysis of the source, spanning scales from a few light-days to a few Mpc, and discuss its potential evolutionary path. [ABSTRACT FROM AUTHOR]

We report our counterpart identification study for two high-energy neutrino events IC-130127A and IC-131204A listed in the IceCube Event Catalog of Alert Tracks. These two events belong to Gold alerts, which have a significant probability of being of astrophysical origin. Within the events' 90% positional uncertainty regions, we, respectively, find PKS 2332–017 and PMN J1916–1519. The first source is a flat-spectrum radio quasar at redshift z = 1.18, and the second is a blazar of an uncertain type with photometric z = 0.968. As they correspondingly had a γ -ray flare temporally coincident with the arrival times of IC-130127A and IC-131204A, we identify them as the respective neutrino emitters. Detailed analysis of the γ -ray data for the two blazars, obtained with the Large Area Telescope onboard the Fermi Gamma-ray Space Telescope, is conducted. The two flares, respectively, from PKS 2332–017 and PMN J1916–1519 lasted ~4 yr and ~4 months and showed possible emission hardening by containing high-energy ~2–10 GeV photons in the emissions. Accompanying the flare of PKS 2332–017, optical and mid-infrared brightening variations were also observed. We discuss the properties of the two sources and compare the properties with those of the previously reported (candidate) neutrino-emitting blazars. [ABSTRACT FROM AUTHOR]

To test the scenario that outflows accelerated by active galactic nuclei (AGN) have a major impact on galaxy-wide scales, we have analysed deep Very Large Telescope/Multi Unit Spectroscopic Explorer (VLT/MUSE) data for the type-2 quasar/ultraluminous infrared galaxy F13451+1232 – an object that represents the major mergers considered in some models of galaxy evolution. After carefully accounting for the effects of atmospheric seeing that had smeared the emission from known compact nuclear outflows across the MUSE field of view, we find that the large-scale kinematics in F13451+1232 are consistent with gravitational motions that are expected in a galaxy merger. Therefore, the fast (⁠|$\mathrm{W_{80}}\gt 500$|  km s |$^{-1}$|⁠) warm-ionized AGN-driven outflows in this object are limited to the central |$\sim$| 100 pc of the galaxy, although we cannot rule out larger scale, lower velocity outflows. Moreover, we directly demonstrate that failure to account for the beam-smearing effects of atmospheric seeing would have led to the mass outflow rates and kinetic powers of spatially extended emission being overestimated by orders of magnitude. We also show that beam-smeared compact-outflow emission can be significant beyond radial distances of 3.5 arcsec (more than 8 times the radius of the seeing disc), and support the argument that some previous claims of large-scale outflows in active galaxies were likely the result of this effect rather than genuine galaxy-wide (⁠|$r\gt 5$|  kpc) outflows. Our study therefore provides further evidence that warm-ionized AGN-driven outflows are limited to the central kiloparsecs of galaxies and highlights the critical importance of accounting for atmospheric seeing in ground-based observational studies of active galaxies. [ABSTRACT FROM AUTHOR]

In our previous study, we identified a shift in the synchrotron peak frequency of the blazar B2 1308+326 from 1012.9 to 1014.8 Hz during a flare, suggesting it could be a changing-look blazar (CLB). In this work, we investigate the changing-look behaviour of B2 1308+326 by analysing a newly acquired optical spectrum and comparing it with an archival spectrum. We find that between the two epochs, the continuum flux increased by a factor of ~4.4, while the Mg ii emission line flux decreased by a factor of 1.4 ± 0.2. Additionally, the equivalent width of the Mg ii line reduced from ~20 to ~3 Å, indicating an apparent shift from a flat-spectrum radio quasar (FSRQ) class to a BL Lacertae (BL Lac) class. Despite this apparent change, the ratio of accretion disk luminosity to Eddington luminosity remains >10−2 during both epochs, indicating efficient accretion persists in B2 1308+326. The measured black hole mass remains consistent with an average log M BH = 8.44 M ⊙. Our findings suggest that B2 1308+326 is not a genuine CLB but rather an intrinsic FSRQ that emerges as a BL Lac during high-flux states due to enhanced nonthermal emission. [ABSTRACT FROM AUTHOR]

We perform the first measurement of the thermal and ionization state of the intergalactic medium (IGM) across |$0.9 \lt z \lt 1.5$| using 301 Ly  |$\,\alpha$| absorption lines fitted from 12 archival Hubble Space Telescope Space Telescope Imaging Spectrograph quasar spectra. We employ the machine-learning-based inference method that uses joint Doppler parameter–column density (⁠|$b{-}N_{{\rm {H\,{\small I}}}{}}$|⁠) distributions obtained from Ly |$\,\alpha$| forest decomposition. Our results show that the H  i photoionization rates, |$\Gamma _{{\rm {H\,{\small I}}}{}}$|⁠ , agree with recent ultraviolet background synthesis models, with |$\log (\Gamma _{{\rm{H\,{\small I}}}}/\text{s}^{-1})={-11.79}^{+0.18}_{-0.15}$|⁠ , |${-11.98}^{+0.09}_{-0.09}$|⁠ , and |${-12.32}^{+0.10}_{-0.12}$| at |$z=1.4$|⁠ , 1.2, and 1, respectively. We obtain the IGM temperature at the mean density, |$T_0$|⁠ , and the adiabatic index, |$\gamma$|⁠ , as |$[\log (T_0/\text{K}), \gamma ]=$| [ |${4.13}^{+0.12}_{-0.10}$|⁠ , |${1.34}^{+0.10}_{-0.15}$| ], |$[{3.79}^{+0.11}_{-0.11}$|⁠ , |${1.70}^{+0.09}_{-0.09}]$|⁠ , and |$[{4.12}^{+0.15}_{-0.25}$|⁠ , |${1.34}^{+0.21}_{-0.26}]$| at |$z=1.4$|⁠ , 1.2, and 1. Our measurements of |$T_0$| at |$z=1.4$| and 1.2 are consistent with the trend predicted from previous |$z\lt 3$| temperature measurements and theoretical expectations, where the IGM cools down after He  ii reionization in the absence of any non-standard heating. However, our |$T_0$| measurement at |$z=1$| shows unexpectedly high IGM temperature. Given the relatively large uncertainty in these measurements, where |$\sigma _{T_0} \sim 5000$|  K, mostly emanating from the limited size of our data set, we cannot conclude whether the IGM cools down as expected. Lastly, we generate mock data sets to test the constraining power of future measurement with larger data sets. The results demonstrate that, with redshift path-length |$\Delta z \sim 2$| for each redshift bin, three times the current data set, we can constrain the |$T_0$| of IGM within 1500 K, which would be sufficient to constrain the IGM thermal history at |$z \lt 1.5$| conclusively. [ABSTRACT FROM AUTHOR]

We present a concise report on the two-dimensional (2D) hybrid method, an innovative extension of 2D correlation spectroscopy, tailored for quasar light curve analysis. Addressing the challenge of discerning periodic variations against the background of intrinsic "red" noise fluctuations, this method employs cross-correlation of wavelet transform matrices to reveal distinct correlation patterns between underlying oscillations, offering new insights into quasar dynamics. [ABSTRACT FROM AUTHOR]

We study the variability of the thermal (accretion disc) and non-thermal (jet) emission of thirteen flat spectrum radio quasars in the optical and near infrared (OIR) regime using light curves spanning years with an average sampling of three observations per week. We fit a combination of a blackbody and a power-law function to the OIR data, in the blazar rest frame, to extract the corresponding thermal (disc) and non-thermal (jet) components from the total flux. We carry out this analysis for the entire duration of the light curves to obtain the variation of the disc and jet components over years. Reliability of our fits have been affirmed by successfully retrieving accurate parameters by employing our method to simulated data and by comparing our results with published disc luminosity obtained by other methods for a few well-observed blazars. In blazars, the thermal (disc) emission is difficult to extract because the relativistically beamed radiation of the jet dominates at all wavelengths. By employing this method, the disc emission in blazars may be estimated directly from photometric data at OIR bands instead of indirect methods, such as, inferring it from the emission line luminosities. We find that the variability of the disc and jet emission obtained by the above method are strongly correlated in most cases. [ABSTRACT FROM AUTHOR]

We examine lengthy radio light curves of the flat spectrum radio galaxy 3C 454.3 for possible quasiperiodic oscillations (QPOs). The data used in this work were collected at five radio frequencies, 4.8, 8.0, 14.5, 22.0, and 37.0 GHz between 1979 and 2013 as observed at the University of Michigan Radio Astronomical Observatory, Crimean Astrophysical Observatory, and Aalto University Metsähovi Radio Observatory. We employ generalized Lomb–Scargle periodogram and weighted wavelet transform analyses to search for periodicities in these light curves. We confirm a QPO period of ∼2000 days to be at least 4 σ significant using both methods at all five radio frequencies between 1979 and 2007, after which a strong flare changed the character of the light curve. We also find a ∼600 day period, which is at least 4 σ significant, but only in the 22.0 and 37.0 GHz light curves. We briefly discuss physical mechanisms capable of producing such variations. [ABSTRACT FROM AUTHOR]

Active galactic nuclei (AGN) are the signposts of black hole growth, and likely play an important role in galaxy evolution. An outstanding question is whether AGN of different spectral types indicate different evolutionary stages in the coevolution of black holes and galaxies. We present the angular correlation function between an AGN sample selected from Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) optical photometry and Wide-field Infrared Survey Explorer mid-IR photometry and a luminous red galaxy (LRG) sample from HSC-SSP. We investigate AGN clustering strength as a function of luminosity and spectral features across three independent HSC fields totaling ∼600 deg2, for z ∈ 0.6 −1.2 and AGN with L 6 μ m > 3 × 1044 erg s−1. There are ∼28,500 AGN and ∼1.5 million LRGs in our primary analysis. We determine the average halo mass for the full AGN sample (M h ≈ 1012.9 h −1 M ⊙), and note that it does not evolve significantly as a function of redshift (over this narrow range) or luminosity. We find that, on average, unobscured AGN (M h ≈ 1013.3 h −1 M ⊙) occupy ∼4.5× more massive halos than obscured AGN (M h ≈ 1012.6 h −1 M ⊙), at 5 σ statistical significance using 1D uncertainties, and at 3 σ using the full covariance matrix, suggesting a physical difference between unobscured and obscured AGN, beyond the line-of-sight viewing angle. Furthermore, we find evidence for a halo mass dependence on reddening level within the Type I AGN population, which could support the existence of a dust-obscured phase. However, we also find that quite small systematic shifts in the redshift distributions of the AGN sample could explain current and previously observed differences in M h . [ABSTRACT FROM AUTHOR]

The stochastic photometric variability of quasars is known to follow a random-walk phenomenology on emission time-scales of months to years. Some high-cadence rest-frame optical monitoring in the past has hinted at a suppression of variability amplitudes on shorter time-scales of a few days or weeks, opening the question of what drives the suppression and how it might scale with quasar properties. Here, we study a few thousand of the highest luminosity quasars in the sky, mostly in the luminosity range of |$L_{\rm bol}$| |$=[46.4, 47.3]$| and redshift range of |$z=[0.7, 2.4]$|⁠. We use a data set from the NASA/Asteroid Terrestrial-impact Last Alert System facility with nightly cadence, weather permitting, which has been used before to quantify strong regularity in longer term rest-frame-UV variability. As we focus on a careful treatment of short time-scales across the sample, we find that a linear function is sufficient to describe the UV variability structure function. Although the result can not rule out the existence of breaks in some groups completely, a simpler model is usually favoured under this circumstance. In conclusion, the data are consistent with a single-slope random walk across rest-frame time-scales of |$\Delta t=[10, 250]$| d. [ABSTRACT FROM AUTHOR]

We exploit the VST ATLAS quasar (QSO) catalogue to perform three measurements of the quasar halo mass profile. First, we make a new estimate of the angular autocorrelation function of ≈230 000 ATLAS quasars with |$z_{\rm photo}\lesssim 2.5$| and |$17 < g < 22$|⁠. By comparing with the |$\Lambda$| CDM mass clustering correlation function, we measure the quasar bias to be |$b_{\rm Q}\approx 2.1$|⁠ , implying a quasar halo mass of |$M_{\rm halo} \approx 8.5\times 10^{11}\,h^{-1}\,{\rm M}_\odot$|⁠. Second, we cross-correlate these |$z\approx 1.7$| ATLAS quasars with the Planck cosmic microwave background (CMB) lensing maps, detecting a somewhat stronger signal at |$4\,{\rm arcmin} < \theta < 60\,{\rm arcmin}$| than previous authors. Scaling these authors' model fit to our data, we estimate a quasar host halo mass of |$M_{\rm halo}\approx 8.3\times 10^{11}\,h^{-1}\,{\rm M}_\odot$|⁠. Third, we fit halo occupation sistribution (HOD) model parameters to our quasar autocorrelation function and from the derived halo mass function, we estimate a quasar halo mass of |$M_{\rm halo}\approx 2.5\times 10^{12}\,h^{-1}\,{\rm M}_\odot$|⁠. We then compare our HOD model prediction to our quasar-CMB lensing result, confirming their consistency. We find that most (≈2/3) QSOs have halo masses within a factor of ≈3 of this average mass. An analysis based on the probability of X-ray detections of AGN in galaxies and the galaxy stellar mass function gives a similarly small mass range. Finally, we compare the quasar halo mass and luminosity functions and suggest that gravitational growth may produce the constant space density with redshift seen in the quasar luminosity function. [ABSTRACT FROM AUTHOR]

We cross-correlate a low-contamination subset of the VST ATLAS |$g\lt 22.5$| quasar catalogue with |$g\lt 21.5$| galaxy clusters, |$r\lt 21$| galaxies and |$r\lt 19.5$| luminous red galaxies (LRGs) to probe their halo mass profiles via quasar magnification bias caused by weak lensing. In the case of galaxy clusters, we find that at small scales their mass profiles are well fitted by Navarro, Frenk, and White models with masses within the expected range. For the galaxies, we find consistency with previous Sloan Digital Sky Survey-based results for the galaxy–quasar cross-correlation and the galaxy auto-correlation functions. Disagreement as to whether the cross-correlation results are in tension with |$\Lambda$| cold dark matter appears due to different assumptions as to whether galaxies trace mass. We conclude that halo occupation distribution (HOD) models fit the galaxy–quasar lensing results better than models where galaxies trace the mass. We further test the cluster and galaxy HOD models in the 2-halo range using the Planck cosmic microwave background (CMB) lensing map, finding that the cross-correlation with both the poorest clusters and the galaxies may be marginally overpredicted by the above HOD models. Finally, we measure the magnification bias of LRGs using both quasar and CMB lensing and find that the observed quasar lensing amplitude may be |${\approx} 2\times$| too high and, on larger scales, the CMB lensing amplitude may be too low to be explained by a standard LRG HOD model. [ABSTRACT FROM AUTHOR]

A detailed broadband spectral and temporal study of a radio-loud active galactic nucleus, 3C 380, is carried out using 14.5 yr of Fermi-LAT data, available Swift observations, and data from other observatories, including AstroSat (2020 August). The source exhibited a GeV outburst on 2020 September 5. Given the sparsity of Swift observations, no useful correlations could be established between γ -ray, X-ray, and UV/optical bands. The source is also a part of the Monitoring of Jets in Active Galactic Nuclei with VLBA Experiments survey and has been monitored at 15 GHz for over a decade. The correlation studies show that radio emission lags γ -rays by ∼150 days. We constrain the location of γ -ray emission by the core shift measurements from the literature and the observed time delays. Using this localization, we constructed and modeled the broadband spectral energy distribution (SED) of the source during its high γ -ray activity states and for the long-term averaged state. The SEDs during the high γ -ray activity states are modeled with two zones: one corresponding to the "steady" or the emission from the source averaged over more than a decade and another corresponding to the "flare" emission. We conclude that the high-energy emission originates within the parsec-scale jet, and moving shocks in the region drive the observed γ -flux variations. [ABSTRACT FROM AUTHOR]

We report the discovery of a hyperluminous type 1 quasar (eFEDS J082826.9-013911; eFEDS J0828-0139) at |$z_{\rm spec} = 1.622$| with a super-Eddington ratio (⁠|$\lambda _{\rm Edd}$|⁠). We perform the optical spectroscopic observations with KOOLS-IFU (the Kyoto Okayama Optical Low-dispersion Spectrograph with optical fiber) on the Seimei Telescope. The black hole mass (⁠|$M_{\rm BH}$|⁠) based on the single-epoch method with Mg  ii |$\lambda$| 2798 is estimated to be |$M_{\rm BH} = {(6.2 \pm 1.2) }\times 10^8\, M_{\odot }$|⁠. To measure the precise infrared luminosity (⁠|$L_{\rm IR}$|⁠), we obtain submillimeter data taken by SCUBA-2 on the James Clerk Maxwell Telescope and conduct the spectral energy distribution analysis with X-ray to submillimeter data. We find that |$L_{\rm IR}$| of eFEDS J0828-0139 is |$L_{\rm IR} = {(6.8 \pm 1.8)} \times 10^{13}\, L_{\odot }$|⁠ , confirming the existence of a hypeluminous infrared galaxy. |$\lambda _{\rm Edd}$| is estimated to be |$\lambda _{\rm Edd} = {3.6 \pm 0.7}$|⁠ , making it a quasar with one of the highest BH mass accretion rates at cosmic noon. [ABSTRACT FROM AUTHOR]

Active galactic nuclei (AGNs) exhibit significant luminosity variations across the entire electromagnetic spectrum, with timescales ranging from hours to years. Studying the optical variability of AGNs provides crucial insights into their physical properties. In this study, we explore the intra-night optical variability (INOV) of AGNs using data from the TESS satellite's all-sky survey. We derive differential light curves for a sample of 56 AGNs from 30-min cadence TESS full-frame images. Our analysis confirms that BL Lac objects typically exhibit stronger INOV compared to quasars, which generally show weaker variability. The duty cycle for INOV with an amplitude greater than 3% is approximately 4 ± 0.7 % for quasars and 22 ± 5 % for BL Lac objects. For INOV with an amplitude exceeding 10%, the corresponding duty cycle decreases to about 0.5 ± 0.3 % and 5 ± 2 % , respectively. Furthermore, we identify a potential linear-log relationship between the duty cycle and the INOV amplitude, based on results from this study and previous findings, particularly from the ARIES program. [ABSTRACT FROM AUTHOR]

The conventional picture of supermassive black-hole growth in the standard model had already been seriously challenged by the emergence of ∼ 10 9 M ⊙ quasars at z ∼ 7.5 , conflicting with the predicted formation of structure in the early Λ CDM Universe. But the most recent JWST discovery of a ∼ 10 8 M ⊙ source at z ∼ 10.1 argues even more strongly against the possibility that these black holes were created in Pop II or III supernovae, followed by Eddington-limited accretion. Attempts at resolving this anomaly have largely focused on the formation of seeds via an exotic, direct collapse of primordial gas to an initial mass ∼ 10 5 M ⊙ – a process that has never been seen anywhere in the cosmos. Our goal in this Letter is to demonstrate that the emergence of these black holes is instead fully consistent with standard astrophysics in the context of the alternative Friedmann–Lemaître–Robertson–Walker cosmology known as the R h = c t universe. We show that, while the predicted evolution in the standard model is overly compressed, the creation, growth and appearance of such high-z quasars fall comfortably within the evolutionary history in this cosmology, thereby adding considerable observational support to the existing body of evidence favoring it over the standard scenario. [ABSTRACT FROM AUTHOR]

Variations in scaling behaviour in the flux and emissions of gravitational lensed quasars can provide valuable information about the dynamics within the sources and their cosmological evolution with time. Here, we study the multifractal behaviour of the light curves (LCs) of 14 lensed quasars with multiple images in the r band, with redshift ranging from 0.657 to 2.730, in the search for potential differences in non-linearity between the signals of the quasar multiple images. Among these lensed systems, nine present two images, two present three images, and three present four images. To this end, we apply the wavelet transform-based multifractal analysis formalism called wavelet transform modulus maxima. We identify strong multifractal signatures in the LCs of the images of all analysed lensed quasar systems, independently of the number of images, with a significant difference between the degree of multifractality of all the images and combinations. We have also searched for a possible connection between the degree of multifractality and the characteristic parameters related to the quasar source and the lensing galaxy. These parameters include the Einstein ring radius and the accretion disc size and the characteristic time-scales related to microlensing variability. The analysis reveals some apparent trends, pointing to a decrease in the degree of multifractality with the increase of the quasar's source size and time-scale. Using a larger sample and following a similar approach, this study confirms a previous finding for the quasar Q0957 + 561. [ABSTRACT FROM AUTHOR]

This is the second in a series of papers in which we use JWST Mid Infrared Instrument multiband imaging to measure the warm dust emission in a sample of 31 multiply imaged quasars, to be used as a probe of the particle nature of dark matter. We present measurements of the relative magnifications of the strongly lensed warm dust emission in a sample of nine systems. The warm dust region is compact and sensitive to perturbations by populations of haloes down to masses |$\sim 10^6$| M |$_{\odot }$|⁠. Using these warm dust flux-ratio measurements in combination with five previous narrow-line flux-ratio measurements, we constrain the halo mass function. In our model, we allow for complex deflector macromodels with flexible third- and fourth-order multipole deviations from ellipticity, and we introduce an improved model of the tidal evolution of subhaloes. We constrain a WDM model and find an upper limit on the half-mode mass of |$10^{7.6}\, {\rm M}_\odot$| at posterior odds of 10:1. This corresponds to a lower limit on a thermally produced dark matter particle mass of 6.1 keV. This is the strongest gravitational lensing constraint to date, and comparable to those from independent probes such as the Ly  |$\alpha$| forest and Milky Way satellite galaxies. [ABSTRACT FROM AUTHOR]

We use the Hubble Space Telescope to analyse the extended [O  iii ] 5007 Å emission in seven bright radio-quiet type 1 quasars (QSO1s), focusing on the morphology and physical conditions of their extended Narrow-Line Regions (NLRs). We find NLRs extending 3–9 kpc, with four quasars showing roughly symmetrical structures (⁠|$b/a$| =1.2–1.5) and three displaying asymmetric NLRs (⁠|$b/a$| =2.4–5.6). When included with type 1 and type 2 AGNs from previous studies, the sizes of the extended [O  iii ] regions scale with luminosity as |$R_{\rm [O\,{\rm {\small III}}]}\sim L_{\rm [O\,{\rm {\small III}}]}^{0.5}$|⁠ , consistent with photoionization. However, when analysed separately, type 1s exhibit a steeper slope (⁠|$\gamma _{1}$| = 0.57 |$\pm$| 0.05) compared to type 2 AGNs (⁠|$\gamma _{2}$| = 0.48 |$\pm$| 0.02). We use photoionization modelling to estimate the maximum NLRs sizes, assuming a minimum ionization parameter of log |$(U)=-3$|⁠ , an ionizing luminosity based on the |$L_{\rm [O\,{\rm {\small III}}]}$| -derived bolometric luminosity, and a minimum gas number density |$n_{\rm H}\sim 100$|  cm |$^{-3}$|⁠ , assuming that molecular clouds provide a reservoir for the ionized gas. The derived sizes agree well with direct measurements for a sample of type 2 quasars, but are underestimated for the current sample of QSO1s. A better agreement is obtained for the QSO1s using bolometric luminosities derived from the 5100 Å continuum luminosity. Radial mass profiles for the QSO1s show significant extended mass in all cases, but with less [O  iii ]-emitting gas near the central AGN compared to QSO2s. This may suggest that the QSO1s are in a later evolutionary stage than QSO2s, further past the blow-out stage. [ABSTRACT FROM AUTHOR]

We study the properties of long gamma-ray burst (GRB) host galaxies using a statistical modelling framework derived to model damped Lyman- |$\alpha$| absorbers (DLAs) in quasar spectra at high redshift. The distribution of |$N_{\rm H\, {\small I}}$| for GRB-DLAs is |$\sim$| 10 times higher than what is found for quasar-DLAs at similar impact parameters. We interpret this as a temporal selection effect due to the short-lived GRB progenitor probing its host at the onset of a starburst where the interstellar medium may exhibit multiple overdense regions. Owing to the larger |$N_{\rm H\, {\small I}}$|⁠ , the dust extinction is larger with 29 per cent of GRB-DLAs exhibiting |$A(V)\gt 1$|  mag in agreement with the fraction of 'dark bursts'. Despite the differences in |$N_{\rm H\, {\small I}}$| distributions, we find that high-redshift |$2 \lt z \lt 3$| quasar- and GRB-DLAs trace the luminosity function of star-forming host galaxies in the same way. We propose that their differences may arise from the fact that the galaxies are sampled at different times in their star formation histories, and that the absorption sightlines probe the galaxy haloes differently. Quasar-DLAs sample the full H  i cross-section, whereas GRB-DLAs sample only regions hosting cold neutral medium. Previous studies have found that GRBs avoid high-metallicity galaxies (⁠|$\sim$| 0.5  |$Z_{\odot }$|⁠). Since at these redshifts galaxies on average have lower metallicities, our sample is only weakly sensitive to such a threshold. Lastly, we find that the modest detection rate of cold gas (H |$_2$| or C  i) in GRB spectra can be explained mainly by a low volume filling factor of cold gas clouds and to a lesser degree by destruction from the GRB explosion itself. [ABSTRACT FROM AUTHOR]

Strong low-ionization transitions like the Mg  ii |$\lambda 2796,2804$|  Å doublet are believed to produce a detectable 'metal-line forest', if metals pollute the neutral intergalatic medium (IGM). We measure the autocorrelation of the Mg  ii forest transmission using 10 ground-based |$z \ge 6.80$| quasar spectra probing the redshift range |$5.96 \lt z_{\rm Mg\, {\small II}} \lt 7.42$| (⁠|$z_{\rm Mg\, {\small II}, median} = 6.47$|⁠). The correlation function exhibits strong small-scale clustering and a pronounced peak at the doublet velocity (⁠|$\Delta v = 768~{\rm km\, s^{-1}}$|⁠) arising from discrete absorbers in the circumgalactic medium of galaxies. After these strong absorbers are identified and masked the signal is consistent with noise. Our measurements are compared to a suite of models generated by combining a large hydrodynamical simulation with a seminumerical reionization topology, assuming a simple uniform enrichment model. We obtain a 95 per cent credibility upper limit of |$[{\rm Mg/H}] \lt -3.73$| at |$z_{\rm Mg\, {\small II},median} = 6.47$|⁠ , assuming uninformative priors on [Mg/H] and the IGM neutral fraction |$x_{\rm {H\, {\small I}}}$|⁠. Splitting the data into low- z (⁠|$5.96 \lt z_{\rm Mg\, {\small II}} \lt 6.47$|⁠ ; |$z_{\rm Mg\, {\small II},median} = 6.235$|⁠) and high- z (⁠|$6.47 \lt z_{\rm Mg\, {\small II}} \lt 7.42$|⁠ ; |$z_{\rm Mg\, {\small II},median} = 6.72$|⁠) subsamples again yields null detections and 95 per cent upper limits of |$[{\rm Mg/H}] \lt -3.75$| and |$\lt -3.45$|⁠ , respectively. These first measurements set the stage for making the Mg ii forest an emerging tool to precisely constrain the Universe reionization and enrichment history. [ABSTRACT FROM AUTHOR]

The James Webb Space Telescope opens a new window to directly probe luminous quasars powered by billion solar mass black holes in the Epoch of Reionization and their coevolution with massive galaxies with unprecedented details. In this paper, we report the first results from a deep NIRSpec integral field unit spectroscopic study of a quasar at z = 7.5. We obtain a bolometric luminosity of ∼1.8 × 1047 erg s−1 and a black hole mass of ∼0.7–2.5 × 109 M ⊙ based on the H β emission line in the quasar spectrum. We discover ∼2 kpc scale, highly blueshifted (∼−870 km s−1) and broad (∼1400 km s−1) [O iii ] line emission after the quasar point-spread function has been subtracted. Such line emission most likely originates from a fast, quasar-driven outflow, the earliest one at galactic scales known so far. The dynamical properties of this outflow fall within the typical ranges of quasar-driven outflows at lower redshift, and the outflow may be fast enough to reach the circumgalactic medium. Combining both the extended and nuclear outflow together, the mass outflow rate, ∼300 M ⊙ yr−1, is ∼60%–380% of the star formation rate of the quasar host galaxy, suggesting that the outflow may expel a significant amount of gas from the inner region of the galaxy. The kinetic energy outflow rate, ∼3.6 × 1044 erg s−1, is ∼0.2% of the quasar bolometric luminosity, which is comparable to the minimum value required for negative feedback based on simulation predictions. The dynamical timescale of the extended outflow is ∼1.7 Myr, consistent with the typical quasar lifetime in this era. [ABSTRACT FROM AUTHOR]

Recent observations from the EIGER JWST program have measured for the first time the quasar–galaxy cross-correlation function at |$z\approx 6$|⁠. The autocorrelation function of faint |$z\approx 6$| quasars was also recently estimated. These measurements provide key insights into the properties of quasars and galaxies at high redshift and their relation with the host dark matter haloes. In this work, we interpret these data building upon an empirical quasar population model that has been applied successfully to quasar clustering and demographic measurements at |$z\approx 2\!-\!4$|⁠. We use a new, large-volume N -body simulation with more than a trillion particles, FLAMINGO-10k, to model quasars and galaxies simultaneously. We successfully reproduce observations of |$z\approx 6$| quasars and galaxies (i.e. their clustering properties and luminosity functions), and infer key quantities such as their luminosity–halo mass relation, the mass function of their host haloes, and their duty cycle/occupation fraction. Our key findings are (i) quasars reside on average in |$\approx 10^{12.5}\, {\rm M}_{\odot }$| haloes (corresponding to |$\approx 5\sigma$| fluctuations in the initial conditions of the linear density field), but the distribution of host halo masses is quite broad; (ii) the duty cycle of (UV-bright) quasar activity is relatively low (⁠|$\approx 1~{{\ \rm per\ cent}}$|⁠); (iii) galaxies (that are bright in [O  iii ]) live in much smaller haloes (⁠|$\approx 10^{10.9}\, {\rm M}_{\odot }$|⁠) and have a larger duty cycle (occupation fraction) of |$\approx 13~{{\ \rm per\ cent}}$|⁠. Finally, we focus on the inferred properties of quasars and present a homogeneous analysis of their evolution with redshift. The picture that emerges reveals a strong evolution of the host halo mass and duty cycle of quasars at |$z\approx 2\!-\!6$|⁠ , and calls for new investigations of the role of quasar activity across cosmic time. [ABSTRACT FROM AUTHOR]

The characteristic timescale at which the variability of active galactic nuclei (AGNs) turns from red noise to white noise can probe the accretion physics around supermassive black holes (SMBHs). A number of works have studied the characteristic timescale of quasars and obtained quite different scaling relations between the timescale and quasar physical properties. One possible reason for the discrepancies is that the characteristic timescale can be easily underestimated if the light curves are not long enough. In this work, we construct well-defined AGN samples to observationally test the relationships between the characteristic timescale and AGN properties obtained by previous works. Our samples eliminate the effects of insufficient light-curve lengths. We confirm that the timescale predictions of the Corona Heated Accretion disk Reprocessing model are consistent with our timescale measurements. The timescale predictions by empirical relations are systematically smaller than our measured ones. Our results provide further evidence that AGN variability is driven by thermal fluctuations in SMBH accretion disks. Future flagship time-domain surveys can critically test our conclusions and reveal the physical nature of AGN variability. [ABSTRACT FROM AUTHOR]

The signal of dipole anisotropy in quasar number counts is studied using the CatWISE2020 catalogue in various colour bins. It is found that the dipole signal differs significantly in two colour bins, namely |$W1-W2\lt 1.1$| and |$W1-W2\gt 1.1$|⁠. While the dipole in the bin |$W1-W2\lt 1.1$| points close to the direction of the cosmic microwave background dipole, the dipole in the bin |$W1-W2\gt 1.1$| points in the direction |$(l,b) = (194^\circ \pm 7^\circ ,19^\circ \pm 4^\circ)$|⁠ , quite close to the Galactic plane. Despite the proximity to the Galactic plane, we are unable to attribute this signal to a Galactic bias. If we interpret the dipole in the bin |$W1-W2\lt 1.1$| as due to our local motion, the extracted velocity turns out to be |$900\pm 113$| km s |$^{-1}$|⁠ , which deviates from the cosmic microwave background dipole velocity with approximately 4.7σ significance. We speculate that the dipole signal in both bins is of cosmological origin and that the difference may be attributed to a redshift dependence of the dipole, representing a departure from the standard |$\Lambda$| CDM model. [ABSTRACT FROM AUTHOR]

Context. Precise millisecond pulsar (MSP) positions determined with very long baseline interferometry (VLBI) hold the key to building the connection between the kinematic and dynamic reference frames respectively used for VLBI and pulsar timing. A frame connection would provide an important pathway to examining the planetary ephemerides used in pulsar timing, and would potentially enhance the sensitivities of the pulsar timing arrays used to detect stochastic gravitational-wave background in the nano-Hz regime. Aims. We aim to significantly improve the precision of the VLBI-based MSP position (from >1 mas at present) by reducing the two dominant components in the positional uncertainty – the propagation-related uncertainty and the uncertainty resulting from the frequency-dependent core shifts of the reference sources. Methods. We introduce a new differential astrometry strategy called PINPT (Phase-screen Interpolation plus frequeNcy-dePendent core shifT correction; pronounced "pinpoint"), which entails the use of multiple calibrators observed at several widely separated frequencies. The strategy allows determination of the core shift and mitigates the impact of residual delay in the atmosphere. We implemented the strategy on PSR J2222-0137, an MSP that is well constrained astrometrically with VLBI and pulsar timing. Results. Using the PINPT strategy, we determined core shifts for four AGNs around PSR J2222-0137, and derived a VLBI-based pulsar position with uncertainties of 0.17 mas and 0.32 mas in Right Ascension and Declination, respectively, approaching the uncertainty level of the best-determined timing-based MSP positions. Additionally, incorporating the new observations into historical ones, we refined the pulsar proper motion and the parallax-based distance to the <10 µas yr-1 level and the subparsec level, respectively. Conclusions. The realization of the PINPT strategy promises a factor-of-five positional precision enhancement (over conventional VLBI astrometry) for all kinds of compact radio sources observed at <2 GHz, including most fast radio bursts. [ABSTRACT FROM AUTHOR]

We studied how eccentricity affects the gravitational wave (GW) spectrum from supermassive black hole (SMBH) binaries. We developed a fast and accurate semi-analytic method for computing the GW spectra, the distribution for the spectral fluctuations and the correlations between different frequencies. As GW emission circularizes binaries, the suppression of the signal strength due to eccentricity is relevant for signals from wider binaries emitting at lower frequencies. Such a feature is present in the signal observed at pulsar timing arrays. We found that when orbital decay of the SMBH binaries is driven by GWs only, the shape of the observed signal preferred highly eccentric binaries ⟨e⟩2nHz =0.830.04−0.05. However, when environmental effects were included, the initial eccentricity could be significantly lowered, yet the scenario with purely circular binaries was still mildly disfavored. [ABSTRACT FROM AUTHOR]

Context. The detection of supermassive black holes (SMBHs) in high-redshift luminous quasars may require a phase of rapid accretion, and as a precondition, substantial gas influx toward seed black holes (BHs) from kiloparsec or parsec scales. Our previous research demonstrated the plausibility of such gas supply for BH seeds within star-forming giant molecular clouds (GMCs) with high surface density (∼104 M⊙ pc−2), facilitating "hyper-Eddington" accretion via efficient feeding by dense clumps, which are driven by turbulence and stellar feedback. Aims. This article presents an investigation of the impacts of feedback from accreting BHs on this process, including radiation, mechanical jets, and highly relativistic cosmic rays. Methods. We ran a suite of numerical simulations to explore diverse parameter spaces of BH feedback, including the subgrid accretion model, feedback energy efficiency, mass loading factor, and initial metallicity. Results. Using radiative feedback models inferred from the slim disk, we find that hyper-Eddington accretion is still achievable, yielding BH bolometric luminosities of as high as 1041 − 1044 erg/s, depending on the GMC properties and specific feedback model assumed. We find that the maximum possible mass growth of seed BHs (ΔMmaxBH) is regulated by the momentum-deposition rate from BH feedback, ṗfeedback/(ṀBHc), which leads to an analytic scaling that agrees well with simulations. This scenario predicts the rapid formation of ∼104 M⊙ intermediate-massive BHs (IMBHs) from stellar-mass BHs within ∼1 Myr. Furthermore, we examine the impacts of subgrid accretion models and how BH feedback may influence star formation within these cloud complexes. [ABSTRACT FROM AUTHOR]

Extended Lyα emission is routinely found around single quasars across cosmic time. However, few studies have investigated how such emission changes in fields with physically associated quasar pairs, which should reside in dense environments and are predicted to be linked through intergalactic filaments. We present VLT/MUSE snapshot observations (45 minutes/source) to unveil extended Lyα emission on scales of the circumgalactic medium (CGM) around the largest sample of physically associated quasar pairs to date, encompassing eight pairs (14 observed quasars) at z ∼ 3 with an i-band magnitude between 18 and 22.75, corresponding to absolute magnitudes Mi(z = 2) between −29.6 and −24.9. The pairs are either at close (∼50–100 kpc, five pairs) or wide (∼450–500 kpc, three pairs) angular separation and have velocity differences of Δv ≤ 2000 km s−1. We detected extended emission around 12 of the 14 targeted quasars and investigated the luminosity, size, kinematics, and morphology of these Lyα nebulae. On average, they span about 90 kpc and are 2.8 × 1043 erg s−1 bright. Irrespective of the quasars' projected distance, the nebulae often (∼45%) extend toward the other quasar in the pair, leading to asymmetric emission whose flux-weighted centroid is at an offset position from any quasar location. We show that large nebulae are preferentially aligned with the large-scale structure, as traced by the direction between the two quasars, and conclude that the cool gas (104 K) in the CGM traces well the direction of cosmic web filaments. Additionally, the radial profile of the Lyα surface brightness around quasar pairs can be described by a power law with a shallower slope (∼−1.6) with respect to single quasars (∼−2), indicative of increased CGM densities out to large radii and/or an enhanced contribution from the intergalactic medium (IGM) due to the dense environments expected around quasar pairs. The sample presented in this study contains excellent targets for ultra-deep observations to directly study filamentary IGM structures in emission. This work demonstrates that a large snapshot survey of quasar pairs will pave the way to direct statistical study of the IGM. [ABSTRACT FROM AUTHOR]

Context. Despite the increasing prevalence of radio-loud (RL) sources at cosmic noon, our understanding of the underlying physics that governs the accretion disc outflows in these particular sources and its dissimilarity with radio-quiet (RQ) quasars remains somewhat limited. Aims. Disentangling the real impact of the radio-loudness and accretion on the outflow parameters remains a challenge to this day. We present ten new spectra of high-redshift and high-luminosity quasars and combine these with previous data at both high and low redshift with the aim being to evaluate the role of the feedback from RL and RQ AGN. The final high-redshift (1.5 ≲ z ≲ 3.9), high-luminosity (47.1 ≤ log(L) ≤ 48.5) sample consists of a combination of 60 quasars from our ISAAC and the Hamburg-ESO surveys. The low-redshift (z ≤ 0.8) sample has 84 quasars that have been analyzed in the optical and with the Faint Object Spectrograph (FOS) data in the UV. Methods. We perform a multicomponent analysis of optical and UV emission line profiles along the quasar main sequence, and provide a relation that can be used to estimate the main outflow parameters (mass rate, thrust, and kinetic power) in both the BLR and NLR through the analysis of the [O III]λ5007 and C IVλ1549 emission lines. Results. Spectrophotometric properties and line profile measurements are presented for Hβ+[O III]λλ4959,5007, Si IVλ1397+O IV]λ1402, C IVλ1549+He IIλ1640, and the 1900 Å blend. High-ionization lines, such as C IVλ1549 and [O III]λ5007, usually present a significant asymmetry toward the blue, especially in radio-quiet sources. This is strong evidence of outflow motions. In the ISAAC sample, 72% of the quasars where [O III] is clearly detected present significant outflows, with centroid velocity at half intensity blueshifted to values of greater than ∼250 km s−1. Radio-loud quasars tend to present slightly more modest blueshifted components in both the UV and optical ranges. The behavior of [O III]λ5007 mirrors that of C IVλ1549, with blueshift amplitudes between the two lines showing a high degree of correlation, which appears unaffected by the presence of radio emission. Conclusions. In contrast to the situation at low redshift, both RL and RQ AGN outflow parameters at high luminosity appear in the range needed to provide feedback effects on their host galaxies. Both high- and low-z RL quasars exhibit smaller outflows compared to RQ quasars, suggesting a potential role of radio-loudness in mitigating outflow effects. Nevertheless, the radio-loudness effect on AGN feedback is much less significant than the effect of accretion, with this latter emerging as the main driver of nuclear outflows. [ABSTRACT FROM AUTHOR]

We present a comprehensive study of the physical origin of radio emission in optical quasars at redshifts z < 2.5. We focus particularly on the associations between compact radio emission, dust reddening, and outflows identified in our earlier work. Leveraging the deepest low-frequency radio data available to date (LoTSS Deep DR1), we achieve radio detection fractions of up to 94%, demonstrating the virtual ubiquity of radio emission in quasars, and a continuous distribution in radio loudness. Through our analysis of radio properties, combined with spectral energy distribution modelling of deep multiwavelength photometry, we establish that the primary source of radio emission in quasars is the active galactic nucleus (AGN), rather than star formation. Modelling the dust reddening of the accretion disc emission shows a continuous increase in radio detection in quasars as a function of the reddening parameter E(B − V), suggesting a causal link between radio emission and dust reddening. Confirming previous findings, we observe that the radio excess in red quasars is most pronounced for sources with compact radio morphologies and intermediate radio loudness. We find a significant increase in [O III] and C IV outflow velocities for red quasars not seen in our control sample, with particularly powerful [O III] winds in those around the threshold from radio-quiet to radio-loud. Based on the combined characterisation of radio, reddening, and outflow properties in our sample, we favour a model in which the compact radio emission observed in quasars originates in compact radio jets and their interaction with a dusty, circumnuclear environment. In particular, our results align with the theory that jet-induced winds and shocks resulting from this interaction are the origin of the enhanced radio emission in red quasars. Further investigation of this model is crucial for advancing our understanding of quasar feedback mechanisms and their role in galaxy evolution. [ABSTRACT FROM AUTHOR]

We analyzed Multi Unit Spectroscopic Explorer observations of 42 local z ≲ 0.1 type 1 active galactic nucleus (AGN) host galaxies taken from the Palomar-Green quasar sample and the close AGN reference survey. Our goal was to study the relation between the black hole mass (M•) and bulge stellar velocity dispersion (σe) for type 1 active galaxies. The sample spans black hole masses of 106.0 − 109.2 M⊙, bolometric luminosities of 1042.9 − 1046.0 erg s−1, and Eddington ratios of 0.006 − 1.2. We avoided AGN emission by extracting the spectra over annular apertures. We modeled the calcium triplet stellar features and measured stellar velocity dispersions of σ* = 60 − 230 km s−1 for the host galaxies. We find stellar velocity dispersion values in agreement with previous measurements for local (z ≲ 0.1) AGN host galaxies, but slightly lower compared with those reported for nearby X-ray-selected type 2 quasars. Using a novel annular aperture correction recipe to estimate σe from σ* that considers the bulge morphology and observation beam-smearing, we estimate flux-weighted σe = 60 − 250 km s−1. If we consider the bulge type when estimating M•, we find no statistical difference between the distributions of AGN hosts and the inactive galaxies on the M•–σe plane for M• ≲ 108 M⊙. Conversely, if we do not consider the bulge type when computing M•, we find that both distributions disagree. We find no correlation between the degree of offset from the M•–σe relation and Eddington ratio for M• ≲ 108 M⊙. The current statistics preclude firm conclusions from being drawn for the high-mass range. We argue these observations support notions that a significant fraction of the local type 1 AGNs and quasars have undermassive black holes compared with their host galaxy bulge properties. [ABSTRACT FROM AUTHOR]

Context. The gravitational lens system SDSS J1004+4112 was the first known example of a quasar lensed by a galaxy cluster. The interest in this system has been renewed following the publication of r-band light curves spanning 14.5 years and the determination of the time delays between the four brightest quasar images. Aims. We constrained the quasar accretion disk size and the fraction of the lens mass in stars using the signature of microlensing in the quasar image light curves. Methods. We built the six possible histograms of microlensing magnitude differences between the four quasar images and compared them with simulated model histograms, using a χ2 test to infer the model parameters. Results. We infer a quasar disk half-light radius of R1/2 = (0.70 ± 0.04)RE = (6.4 ± 0.4) √M/0.3M⊙ light-days at 2407 Å in the rest frame and stellar mass fractions at the quasar image positions of αA > 0.059, αB = 0.056+0.021-0.027, αC = 0.030+0.031-0.021, and αD = 0.072+0.034-0.016. Conclusions. The inferred disk size is broadly compatible with most previous estimates, and the stellar mass fractions are within the expected ranges for galaxy clusters. In the region where image C lies, the stellar mass fraction is compatible with a stellar contribution from the brightest cluster galaxy, galaxy cluster members, and intracluster light, but the values at images B, D, and especially A are slightly larger, possibly suggesting the presence of extra stellar components. [ABSTRACT FROM AUTHOR]

Blazars, the peculiar class of active galactic nuclei, are known to show flux variations across the accessible electromagnetic spectrum. Though they have been studied extensively for their flux variability characteristics across wavelengths, information on their ultraviolet (UV) flux variations on timescales of hours is very limited. Here, we present the first UV flux variability study on intraday timescales of a sample of ten blazars comprising two flat-spectrum radio quasars (FSRQs) and eight BL Lacertae objects (BL Lacs). These objects, spanning a redshift (z) range of 0.034 ≤ z ≤ 1.003, were observed in the far-UV (1300−1800 Å) and near-UV (2000−3000 Å) wavebands using the ultraviolet imaging telescope on board AstroSat. UV flux variations on timescales of hours were detected in nine sources out of the observed ten blazars. The spectral variability analysis showed a bluer-when-brighter trend with no difference in the UV spectral variability behavior between the studied sample of FSRQs and BL Lacs. The observed UV flux and spectral variability in our sample of both FSRQs and BL Lacs revealed that the observed UV emission in them is dominated by jet synchrotron process. [ABSTRACT FROM AUTHOR]

Leveraging the photometric data of the Sloan Digital Sky Survey and the Galaxy Evolution Explorer (GALEX), we construct mean/median spectral energy distributions (SEDs) for unique bright quasars in redshift bins of 0.2 and up to z ≃ 3 , after taking the GALEX non-detection into account. Further correcting for the absorption of the intergalactic medium, these mean/median quasar SEDs constitute a surprisingly redshift-independent mean/median composite SED from the rest-frame optical down to ≃ 500   A ˚ for quasars with bolometric luminosity brighter than 10 45.5 erg s − 1 . Moreover, the mean/median composite quasar SED is plausibly also independent of black hole mass and Eddington ratio, and suggests similar properties of dust and gas in the quasar host galaxies since cosmic noon. Both the mean and median composite SEDs are nicely consistent with previous mean composite quasar spectra at wavelengths beyond ≃ 1000   A ˚ , but at shorter wavelengths, are redder, indicating, on average, less ionizing radiation than previously expected. Through comparing the model-predicted to the observed composite quasar SEDs, we favor a simply truncated disk model, rather than a standard thin disk model, for the quasar central engine, though we request more sophisticated disk models. Future deep ultraviolet facilities, such as the China Space Station Telescope and the Ultraviolet Explorer, would prompt revolutions in many aspects, including the quasar central engine, production of the broad emission lines in quasars, and cosmic reionization. [ABSTRACT FROM AUTHOR]

In this paper we explore the properties of the |$z=6.853$| obscured hyperluminous quasar COS-87259, discovered in the Cosmological Evolution Survey (COSMOS) field, with our recently developed Bayesian spectral energy distribution (SED) fitting code SMART (Spectral energy distributions Markov chain Analysis with Radiative Transfer models). SMART fits SEDs exclusively with multicomponent radiative transfer models that constitute four different types of pre-computed libraries for the active galactic nucleus (AGN) torus, the starburst, and the spheroidal or disc host. We explore two smooth radiative transfer models for the AGN torus and two two-phase models, in order to put constraints on the AGN fraction of the galaxy, the black hole mass, and its star formation rate (SFR). We find that either of the smooth tapered disc or the two-phase flared disc models provide a good fit to the SED of COS-87259. The best-fitting models predict an AGN fraction in the range |$86-92$| per cent, a bolometric AGN luminosity of |$5.8-10.3 \times 10^{13} L_\odot$|⁠ , a black hole mass of |$1.8-3.2 \times 10^{9} M_\odot$| (assuming the quasar is accreting at the Eddington limit), and an SFR in the range |$1985-2001~M_\odot \rm yr^{-1}$|⁠. The predicted space density of such objects in the redshift range |$4-7$| is |$\sim 20$| times more than that of co-eval unobscured quasars. [ABSTRACT FROM AUTHOR]

We explore the influence of radio-mode feedback on the properties of the cool circumgalactic medium (CGM). To this end, we assemble a statistical sample of approximately 30,000 radio galaxies with background quasars by combining optical spectroscopic measurements of luminous red galaxies and quasars from the year 1 data set of the Dark Energy Spectroscopic Instrument and radio sources from the LOw-Frequency ARray Two-metre Sky Survey (LoTSS) DR2 catalog and the Very Large Array Sky Survey (VLASS) quick-look catalog. Galaxies with similar optical properties but with no radio counterparts in LoTSS and VLASS are selected as the control group. We measure the cool CGM properties of radio galaxies and their control samples traced by Mg ii absorption lines, including covering fraction, rest equivalent width, and gas kinematics. Our results show no significant difference in the properties of gas around radio galaxies and their control sample, indicating that the operating radio-mode feedback of massive galaxies does not produce detectable effects on the properties of the cool CGM. Finally, we show that the CGM of radio galaxies contains a nonnegligible amount of cool gas with approximately 1010 M ⊙. This abundance can place a stringent constraint on the radio-mode feedback models. [ABSTRACT FROM AUTHOR]

We introduce an improved method for decomposing the emission of active galactic nuclei (AGN) and their host galaxies using templates from principal component analysis (PCA). This approach integrates prior information from PCA with a penalized pixel fitting mechanism that improves the precision and effectiveness of the decomposition process. Specifically, we have reduced the degeneracy and overfitting in AGN host decomposition, particularly for those with low signal-to-noise ratios (SNRs), where traditional methods tend to fail. By applying our method to 76,565 Sloan Digital Sky Survey Data Release 16 quasars with z < 0.8, we achieve a success rate of ≈94%, thus establishing the largest host-decomposed spectral catalog of quasars to date. Our fitting results consider the impact of the host galaxy on the overestimation of the AGN luminosity and black hole mass (M BH). Furthermore, we obtained stellar velocity dispersion (σ ⋆) measurements for 4137 quasars. The slope of the M BH− σ ⋆ relation in this subsample is generally consistent with previous quasar studies beyond the local Universe. Our method provides a robust and efficient approach to disentangle the AGN and host galaxy components across a wide range of SNRs and redshifts. [ABSTRACT FROM AUTHOR]

JWST has brought us new insights into Cosmic Dawn with tentative detection of the unique signatures of metal-free Population III (Pop III) stars, such as strong He II emission, extremely blue ultraviolet spectrum, and enhanced nitrogen abundance. Self-consistent theoretical predictions of the formation rates, sites, and masses of Pop III stars are crucial for interpreting the observations, but are challenging due to complex physical processes operating over the large range of length-scales involved. One solution is to combine analytical models for the small-scale star formation process with cosmological simulations that capture the large-scale physics such as structure formation, radiation backgrounds, and baryon-dark matter streaming motion that regulate the conditions of Pop III star formation. We build an analytical model to predict the final masses of Pop III stars/clusters from the properties of star-forming clouds, based on the key results of small-scale star formation simulations and stellar evolution models. Our model for the first time considers the interplay between feedback and fragmentation and covers different modes of Pop III star formation ranging from ordinary small (⁠|$\sim\!{10{-}2000}\ \rm M_\odot$|⁠) clusters in molecular-cooling clouds to massive (⁠|$\gtrsim\!{10^{4}}\ \rm M_\odot$|⁠) clusters containing supermassive (⁠|$\sim\!{10^{4}{-}3}\times 10^{5}\ \rm M_\odot$|⁠) stars under violent collapse of atomic-cooling clouds with large gas accretion rates of |$\gtrsim\!{0.1}\ \rm M_\odot \ yr^{-1}$|⁠. As an example, the model is applied to the Pop III star-forming clouds in the progenitors of typical haloes hosting high- z luminous quasars (⁠|$M_{\rm h}\sim 10^{12}\ \rm M_\odot$| at |$z\sim 6$|⁠), which shows that formation of Pop III massive clusters is common (⁠|$\sim\!{20{-}70}{{\ \rm per\ cent}}$|⁠) in such biased (⁠|$\sim\!{4}\sigma$|⁠) regions, and the resulting heavy black hole seeds from supermassive stars can account for a significant fraction of observed luminous (⁠|$\gtrsim\!{10^{46}}\ \rm erg\ s^{-1}$|⁠) quasars at |$z\sim 6$|⁠. [ABSTRACT FROM AUTHOR]

We present a focused X-ray and multiwavelength study of the ultraluminous weak-line quasar (WLQ) SDSS J1521+5202, one of the few X-ray weak WLQs that is amenable to basic X-ray spectral and variability investigations. J1521+5202 shows striking X-ray variability during 2006–2023, by up to a factor of ≈32 in 0.5–2 keV flux, and our new 2023 Chandra observation caught it in its brightest X-ray flux state to date. Concurrent infrared/optical observations show only mild variability. The 2023 Chandra spectrum can be acceptably described by a power law with intrinsic X-ray absorption, and it reveals a nominal intrinsic level of X-ray emission relative to its optical/ultraviolet emission. In contrast, an earlier Chandra spectrum from 2013 shows apparent spectral complexity that is not well fit by a variety of models, including ionized absorption or standard Compton-reflection models. Overall, the observations are consistent with the thick-disk plus outflow model previously advanced for WLQs, where a nominal level of underlying X-ray emission plus variable absorption leads to the remarkable observed X-ray variability. In the case of J1521+5202, it appears likely that the outflow, and not the thick disk itself, lies along our line of sight and causes the X-ray absorption. [ABSTRACT FROM AUTHOR]

The Eigenvector 1 schema, or the main sequence of quasars, was introduced as an analogous scheme to the HR diagram that would allow us to understand the more complex, extended sources -active galactic nuclei (AGNs) that harbor accreting supermassive black holes. The study has spanned more than three decades and has advanced our knowledge of the diversity of Type-1 AGNs from both observational and theoretical aspects. The quasar main sequence, in its simplest form, is the plane between the FWHM of the broad Hβ emission line and the strength of the optical Fe II emission to the Hβ. While the former allows the estimation of the black hole mass, the latter enables direct measurement of the metal content and traces the accretion rate of the AGN. Together, they allow us to track the evolution of AGN in terms of the activity of the central nuclei, its effect on the line-emitting regions surrounding the AGN, and their diversity making them suitable distance indicators to study the expansion of our Universe. This mini-reviewaims to provide (i) a brief history leading up to the present day in the study of the quasar main sequence, (ii) introduce us to the many possibilities to study AGNs with the main sequence as a guiding tool, and (iii) highlight some recent, exciting lines of researches at the frontier of this ever-growing field. [ABSTRACT FROM AUTHOR]

In this manuscript, strong clues are reported to support the normal broad line AGN SDSS J1617+0638 as the host galaxy harbouring a central tidal disruption event (TDE). Through the optical flare in the CSS 8.5yr-long light curve and the none-variability in the up-to-date ASAS-SN light curves, the theoretical TDE model described by the mosfit code can be applied in SDSS J1617+0638. Meanwhile, considering the assumed central TDE expected continuum emissions not strong enough to describe the continuum emissions in the SDSS spectrum of SDSS J1617+0638, an additional power-law component from pre-existing AGN activity should be necessary in SDSS J1617+0638. Furthermore, considering the short time duration to the observed date for the SDSS spectrum from the starting time of the assumed central TDE in SDSS J1617+0638, TDE model expected accreting mass only about 0.03 |$\mathrm{ M}_\odot$| can lead to few effects of TDEs debris on the observed broad emission lines in the SDSS spectrum of SDSS J1617+0638, indicating the TDE model determined BH mass simply consistent with the virial BH mass by broad emission lines, as determined results in SDSS J1617+0638. Therefore, through both the photometric variability and the spectroscopic results, a central TDE can be preferred in the normal broad line AGN SDSS J1617+0638 with pre-existing central AGN activity and pre-existing broad emission line regions. [ABSTRACT FROM AUTHOR]

We estimated values of spin, mass, and inclination angle for sample of 42 red quasars. Our estimations show that two objects: F2MS J1113+1244 and F2MS J1434+0935 with the highest Eddington ratios may have geometrically thick disk. Six objects: SDSS J0036‐0113, S82X 0040+0058, S82X 0118+0018, S82X 0303‐0115, FBQS J1227+3214, S82X 2328‐0028 may have "retrograde" rotation. Analysis of estimated spin values shows that red quasar population may contain Seyfert galaxies and NLS1. [ABSTRACT FROM AUTHOR]

The unified model of jetted active galactic nuclei (AGNs) based on intrinsic properties presumes that the blazar subtypes of BL Lacertae objects (BLs) and flat-spectrum radio quasars (FSRQs) are aligned equivalents of Fanaroff–Riley type I (FR I) and Fanaroff–Riley type II (FR II) radio galaxies (RGs) from where their parent sources are obtained. Using compiled radio, X-ray and γ -ray data of 397 Fermi Large Area Telescope (Fermi-LAT) blazars and 153 non-Fermi detected RGs, we computed the γ -ray core-dominance parameter (Rγ) and γ -ray emission components (beamed and unbeamed) to study the consequences of relativistic beaming and orientation effects on γ -ray properties of radio RGs, BLs and FSRQs. Data analysis shows that the distributions of RX and Rγ, on average, are consistent with the prediction of the unified scheme in which FSRQs and BLs are strongly beamed and inclined at smaller angles than RGs. Through statistical tests with chance probability, p < 0.05 , we find that the distributions of RX and Rγ for radio galaxies and the blazar subtypes are not significantly different. There is a regular positive trend (r > + 0.60 ) in the variation of radio core-dominance parameter – X-ray luminosity (R − L x ) data from radio galaxies to FSRQs through BLs, which suggests that radio galaxies could be relativistically less beamed population of jetted AGNs. The results are consistent with the unified model for radio galaxies and the conventional blazar subtypes. [ABSTRACT FROM AUTHOR]

Broad absorption line (BAL) outflows are commonly detected in active galactic nuclei (AGNs), but their driving mechanism remains poorly constrained. Here, we investigate whether radiation pressure on dust can adequately explain the BAL phenomenon observed in quasars. In the framework of our AGN radiative dusty feedback scenario, we show that dust-driven outflows can reach BAL wind-like velocities (⁠|$v \sim 10^4$| km s |$^{-1}$|⁠) on galactic scales (⁠|$r \lesssim 1$| kpc). This is consistent with recent observations indicating that BAL acceleration typically occurs on scales of |$\sim 10$| pc, and that the majority of BAL outflows are located at galactocentric radii greater than |$\sim 100$| pc. We derive the outflow radial velocity profile and compute the associated outflow momentum rate and kinetic power, which are found to be in agreement with the outflow energetics measured in BAL quasars. Therefore, radiation pressure on dust may account for the observed BAL outflow dynamics and energetics. Furthermore, we consider BAL clouds/clumps (leading to a clumpy BAL flow characterized by a wide range of outflowing velocities), and we analyse how the resulting covering factors affect the shape of the absorption line profiles. We conclude that dust-driven BAL outflows may provide a significant contribution to AGN feedback on galactic scales. [ABSTRACT FROM AUTHOR]

We measure the three-dimensional power spectrum (P3D) of the transmitted flux in the Lyman- |$\alpha$| (Ly  |$\alpha$|⁠) forest using the complete extended Baryon Oscillation Spectroscopic Survey data release 16 (eBOSS DR16). This sample consists of |$\sim$| 205 000 quasar spectra in the redshift range |$2\le z \le 4$| at an effective redshift |$z=2.334$|⁠. We propose a pair-count spectral estimator in configuration space, weighting each pair by |$\exp (i\mathbf {k}\cdot \mathbf {r})$|⁠ , for wave vector |$\mathbf {k}$| and pixel pair separation |$\mathbf {r}$|⁠ , effectively measuring the anisotropic power spectrum without the need for fast Fourier transforms. This accounts for the window matrix in a tractable way, avoiding artefacts found in Fourier-transform based power spectrum estimators due to the sparse sampling transverse to the line of sight of Ly  |$\alpha$| skewers. We extensively test our pipeline on two sets of mocks: (i) idealized Gaussian random fields with a sparse sampling of Ly  |$\alpha$| skewers, and (ii) log-normal LyaCoLoRe mocks including realistic noise levels, the eBOSS survey geometry and contaminants. On eBOSS DR16 data, the Kaiser formula with a non-linear correction term obtained from hydrodynamic simulations yields a good fit to the power spectrum data in the range |$(0.02 \le k \le 0.35)\, h\, {\rm Mpc}^{-1}\,$| at the 1–2σ level with a covariance matrix derived from LyaCoLoRe mocks. We demonstrate a promising new approach for full-shape cosmological analyses of Ly  |$\alpha$| forest data from cosmological surveys such as eBOSS, the currently observing Dark Energy Spectroscopic Instrument and future surveys such as the Prime Focus Spectrograph, WEAVE-QSO, and 4MOST. [ABSTRACT FROM AUTHOR]

LSST will catalogue the light curves of up to 100 million quasars. Among these there can be |$\sim$| 100 ultra-compact massive black hole (MBH) binaries, whose gravitational waves (GWs) can be detected 5–15 yr later by LISA. Here, we assume such a LISA detection occurred, and assess whether or not its electromagnetic (EM) counterpart can be identified as a periodic quasar in archival LSST data. We use the binary's properties derived from the LISA waveform, including the evolution of its orbital frequency, its total mass, distance, and sky localization, to predict the redshift, magnitude, and historical periodicity of the quasar expected in the LSST data. We then use Monte Carlo simulations to compute the false alarm probability (FAP), i.e. the number of quasars in the LSST catalogue matching these properties by chance, based on the (extrapolated) quasar luminosity function, the cadence of LSST, and intrinsic 'damped random walk' quasar variability. We analyse four fiducial LISA binaries, with masses and redshifts of |$(M_{\rm bin}/{\rm M_{\odot }},z) = (3\times 10^5,0.3)$|⁠ , |$(3\times 10^6,0.3)$|⁠ , |$(10^7,0.3)$|⁠ , and |$(10^7,1)$|⁠. While noise and aliasing due to LSST's cadence produces false periodicities by chance, we find that the frequency chirp of the LISA source during the LSST observations washes out these noise peaks and allows the genuine source to stand out in appropriately scaled Lomb–Scargle periodograms. We find that all four fiducial binaries can be uniquely identified, with |${\rm FAP}\lt 10^{-5}$|⁠ , a week or more before merger. This should enable follow-up EM observations targeting individual EM counterparts during their inspiral stage. [ABSTRACT FROM AUTHOR]

Reconstructing the intrinsic Ly  |$\alpha$| line flux from high- z QSOs can place constraints on the neutral hydrogen content of the intergalactic medium during reionization. There are now |$\gtrsim 10$| different Ly  |$\alpha$| reconstruction pipelines using different methodologies to predict the Ly  |$\alpha$| line flux from correlations with the spectral information redwards of Ly  |$\alpha$|⁠. However, there have been few attempts to directly compare the performance of these pipelines. Therefore, we devised a blind QSO challenge to compare these reconstruction pipelines on a uniform set of objects. Each author was provided de-identified, observed rest-frame QSO spectra with spectral information only redwards of 1260 Å rest-frame to ensure unbiased reconstruction. We constructed two samples of 30 QSOs, from X-Shooter and Sloan Digital Sky Survey (SDSS) both spanning |$3.5\lt z\lt 4.5$|⁠. Importantly, the purpose of this comparison study was not to champion a single, best-performing reconstruction pipeline but rather to explore the relative performance of these pipelines over a range of QSOs with broad observational characteristics to infer general trends. In summary, we find machine-learning approaches in general provide the strongest 'best guesses' but underestimate the accompanying statistical uncertainty, although these can be recalibrated, while pipelines that decompose the spectral information, for example principal component or factor analysis, generally perform better at predicting the Ly  |$\alpha$| profile. Further, we found that reconstruction pipelines trained on SDSS QSOs performed similarly on average for both the X-Shooter and SDSS samples indicating no discernible biases owing to differences in the observational characteristics of the training set or QSO being reconstructed, although the recovered distributions of reconstructions for X-Shooter were broader likely due to an increased fraction of outliers. [ABSTRACT FROM AUTHOR]