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In this paper, we analyze the light variation of KIC 8840638 using high-precision time-series data from the Kepler mission. The analysis reveals that this target is a new detached eclipsing binary system with a δ Scuti component, rather than a single δ Scuti star as previously known. The frequency analysis of short-cadence data reveals 95 significant frequencies, most of which lie in a frequency range of 23−32 day−1. Among them, seven independent frequencies are detected in the typical frequency range of δ Scuti stars, and they are identified as pressure modes. In addition, a possible large separation value of Δ ν = 36.5 ± 0.1 μ Hz is also detected with the Fourier transform (FT) and autocorrelation function (AC) analysis. The orbital frequency f orb (= 0.320008 day−1) and its harmonics are also detected directly in the frequency spectrum. The binary modelings derived from PHOEBE indicate that this binary system is in detached configurations with a mass ratio of q = 0.33 − 0.04 + 0.06 , an inclination angle of 40.19 − 2.84 + 3.96 ​​​​​°. The derived parameters and binary evolutionary model suggest that the primary star is an object on the verge of leaving the main sequence with a temperature of ∼7600 K, while the secondary appears to be a cool component entering the giant branch with a temperature ∼3100 K lower than the primary. Moreover, this system may have undergone a mass ratio reversal, where the more massive star is the gainer component and the less massive one is the donor star. [ABSTRACT FROM AUTHOR]

Narrow-line Seyfert 1 (NLS1) galaxies are an important type of active galactic nucleus (AGN), generally expected to be accreting at a high Eddington rate. The properties of their outflows and importance of AGN feedback remain intriguing. We report on the discovery of fast outflowing warm absorbers (WAs) in the NLS1 PG 1001+054 with velocities in the range of ∼7000–9000 km s−1. They are identified with blueshifted Ly α, N v, and Si iv lines in the high-resolution ultraviolet (UV) spectra taken with the Cosmic Origins Spectrograph on board the Hubble Space Telescope. We perform photoionization modeling using XSTAR with three WAs. The derived physical properties are typical of WAs in terms of ionization and column density, whereas the outflow velocities are significantly higher. The estimated location of these WAs ranges from 1 to 73 parsecs away from the AGN. Together with previous detection of high ionization absorbers in the X-ray for PG 1001+054, we suggest that fast outflowing UV absorbers are probably part of a multiphase outflow. Such a structure is likely produced by the outflow launched from the AGN at an accretion disk scale, which shocks the ambient interstellar medium (ISM), producing stratified absorbers. Assuming contribution from the three WAs at tens of parsecs, the estimated ratio between the kinetic power of the outflow and AGN Eddington luminosity could reach 1.7%, raising the possibility of sufficient influence on the host galaxy when compared to some theoretical models for efficient AGN feedback. [ABSTRACT FROM AUTHOR]

Changing-look active galactic nucleus NGC 4151, which has attracted a lot of attention, is undergoing the second dramatic outburst stage in its evolutionary history. To investigate the geometry and kinematics of the broad-line region (BLR), and measure the mass of supermassive black hole in NGC 4151, we perform a 7 month photometric and spectroscopic monitoring program in 2020â€"2021, using the 2.4 m telescope at Lijiang Observatory. We successfully measure the time lags of the responses from broad H α, H β, H Îł, He i, and He ii emission lines to continuum variation, which are 7.63 âˆ' 2.62 + 1.85 , 6.21 âˆ' 1.13 + 1.41 , 5.67 âˆ' 1.94 + 1.65 , 1.59 âˆ' 1.11 + 0.86 , and 0.46 âˆ' 1.06 + 1.22 days, respectively, following radial stratification. The ratios of time lags among these lines are 1.23: 1.00: 0.91: 0.26: 0.07. We find that the continuum lag between the ultraviolet and optical bands can significantly affect the lag measurements of He i and He ii. Virial and infalling gas motions coexist in this campaign, which is different from previous results, implying the evolutionary kinematics of BLR. Based on our measurements and previous ones in the literature, we confirm that the BLR of NGC 4151 is basically virialized. Finally, we compute the black hole mass through multiple lines, and the measurement from H β to be 3.94 âˆ' 0.72 + 0.90 Ă— 10 7 M ⊙ , which is consistent with previous results. The corresponding accretion rate is 0.02 âˆ' 0.01 + 0.01 L Edd c âˆ' 2 , implying a sub-Eddington accretor. [ABSTRACT FROM AUTHOR]

We report a single-lined white dwarfâ€"main-sequence binary system, LAMOST J172900.17+652952.8, which is discovered by the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST)’s medium-resolution time-domain surveys. The radial-velocity semi-amplitude and orbital period of the optical visible star are measured by using follow-up observations with the Palomar 200 inch telescope and light curves from the Transiting Exoplanet Survey Satellite (TESS). Thus the mass function of the invisible candidate white dwarf is derived, f (M 2) = 0.120 ± 0.003 M ⊙. The mass of the visible star is measured based on a spectral energy distribution fitting, M 1 = 0.81 âˆ' 0.06 + 0.07 M ⊙ . Hence, the mass of its invisible companion is M 2 ≳ 0.63 M ⊙. The companion ought to be a compact object rather than a main-sequence star owing to the mass ratio q = M 2/ M 1 ≳ 0.78 and the single-lined spectra. The compact object is likely to be a white dwarf if the inclination angle is not small, i ≳ 40°. By using the Galaxy Evolution Explorer (GALEX) near-UV flux, the effective temperature of the white dwarf candidate is constrained as T eff WD ≲ 12,000â€"13,500 K. It is difficult to detect white dwarfs which are outshone by their bright companions via single-epoch optical spectroscopic surveys. Therefore, optical time-domain surveys can play an important role in unveiling invisible white dwarfs and other compact objects in binaries. [ABSTRACT FROM AUTHOR]

We present LAMOST J041920.07+072545.4 (hereafter J0419), a close binary consisting of a bloated, extremely low mass pre-white dwarf (pre-ELM WD) and a compact object with an orbital period of 0.607189 days. The large-amplitude ellipsoidal variations and the evident Balmer and He i emission lines suggest a filled Roche lobe and ongoing mass transfer. No outburst events were detected in the 15 years of monitoring of J0419, indicating a very low mass transfer rate. The temperature of the pre-ELM, T eff = 5793 âˆ' 133 + 124 K , makes it cooler than the known ELMs, but hotter than most cataclysmic variable donors. Combining the mean density within the Roche lobe and the radius constrained from our spectral energy distribution fitting, we obtain the mass of the pre-ELM, M 1 = 0.176 ± 0.014 M ⊙. The joint fitting of light and radial velocity curves yields an inclination angle of i = 66.5 âˆ' 1.7 + 1.4 degrees, corresponding to a mass of the compact object of M 2 = 1.09 ± 0.05 M ⊙. The very bloated pre-ELM has a smaller surface gravity ( log g = 3.9 ± 0.01 , R 1 = 0.78 ± 0.02 R ⊙) than the known ELMs or pre-ELMs. The temperature and the luminosity ( L bol = 0.62 âˆ' 0.10 + 0.11 L ⊙ ) of J0419 are close to those of the main sequence, which makes the selection of such systems through the H-R diagram inefficient. Based on the evolutionary model, the relatively long period and small log g indicate that J0419 could be close to the “bifurcation period” in the orbital evolution, which makes J0419 a unique source to connect ELM/pre-ELM WD systems, wide binaries, and cataclysmic variables. [ABSTRACT FROM AUTHOR]

We compile a sample of 92 active galactic nuclei (AGNs) at z < 0.75 with gri photometric light curves from the archival data of the Zwicky Transient Facility and measure the accretion disk sizes via continuum reverberation mapping. We employ Monte Carlo simulation tests to assess the influences of data sampling and broad emission lines and select out the sample with adequately high sampling cadences (3 days apart in average) and minimum contaminations of broad emission lines. The interband time delays of individual AGNs are calculated using the interpolated cross-correlation function, and then these delays are fitted with a generalized accretion disk model, in which interband time delays are a power function of wavelength, black hole mass, and luminosity. A Markov Chain Monte Carlo method is adopted to determine the best parameter values. Overall the interband time delays can be fitted with the τ ∝ λ 4/3 relation as predicted from a steady-state, optically thick, geometrically thin accretion disk; however, the yielded disk size is systematically larger than expected, although the ratio of the measured to theoretical disk sizes depends on using the emissivity- or responsivity-weighted disk radius. These results are broadly consistent with previous studies, all together raising a puzzle about the “standard” accretion disk model. [ABSTRACT FROM AUTHOR]

The quasar 3C 273 has been observed with infrared spectroastrometry (SA) of the broad Pa α line and optical reverberation mapping (RM) of the broad H β line. SA delivers information about the angular size and structure of the Pa α broad-line region (BLR), while RM delivers information about the physical size and structure of the H β BLR. Based on the fact that the two BLRs share the mass of the supermassive black hole (SMBH) and viewing inclination, a combination of SA and velocity-resolved RM (SARM) thereby allows us to simultaneously determine the SMBH mass and geometric distance through dynamically modeling the two BLRs. We construct a suite of dynamical models with different geometric configurations and apply a Bayesian approach to obtain the parameter inferences. Overall the obtained masses and distances are insensitive to specific BLR configurations but more or less depend on parameterizations of the vertical distributions. The most probable model, chosen in light of the Bayes factor, yields an angular-size distance log (D A / Mpc) = 2.83 âˆ' 0.28 + 0.32 and an SMBH mass log (M • / M ⊙) = 9.06 âˆ' 0.27 + 0.21 , which agree with the relationships between SMBH masses and bulge properties. The BLRs have an inclination of 5 âˆ' 1 + 1 degrees, consistent with that of the large-scale jet in 3C 273. Our approach reinforces the capability of SARM analysis to measure SMBH masses and distances of active galactic nuclei and quasars even though SA and RM observations are undertaken with different emission lines and/or in different periods. [ABSTRACT FROM AUTHOR]

The optical light curves of quiescent black hole low-mass X-ray binaries often exhibit significant nonellipsoidal variabilities, showing the photospheric radiation of the companion star is veiled by other sources of optical emission. Assessing this “veiling” effect is critical to the black hole mass measurement. Here in this work, we carry out a strictly simultaneous spectroscopic and photometric campaign on the prototype of black hole low-mass X-ray binary A0620-00. We find that for each observation epoch, the extra optical flux beyond a pure ellipsoidal modulation is positively correlated with the fraction of veiling emission, indicating the accretion disk contributes most of the nonellipsoidal variations. Meanwhile, we also obtain a K2V spectral classification of the companion, as well as the measurements of the companion’s rotational velocity v sin i = 83.8 ± 1.9 km sâˆ'1 and the mass ratio between the companion and the black hole q = 0.063 ± 0.004. [ABSTRACT FROM AUTHOR]

We present the results from a spectroscopic monitoring campaign to obtain reverberation mapping measurements and investigate the broad-line region (BLR) kinematics for active galactic nuclei (AGNs) of Mrk 817 and NGC 7469. This campaign was undertaken with the Lijiang 2.4 m telescope. The median spectroscopic sampling is 2.0 days for Mrk 817 and 1.0 day for NGC 7469. We detect time lags of the broad emission lines, including Hβ, Hγ, He ii, and He i for both AGNs, including Fe ii for Mrk 817 with respect to the varying AGN continuum at 5100 Å. Investigating the relationship between line widths and time lags of the broad emission lines, we find that the BLR dynamics of Mrk 817 and NGC 7469 are consistent with the virial prediction. We estimate the masses of central supermassive black holes (SMBHs) and the accretion rates of both AGNs. Using the data of this campaign, we construct the velocity-resolved lag profiles of the broad Hγ, Hβ, and He i lines for Mrk 817, which show almost the same kinematic signatures in that the time lags in the red wing are slightly larger than the time lags in the blue wing. For NGC 7469, we only clearly construct the velocity-resolved lag profiles of the broad Hγ and Hβ, which show very similar kinematic signatures to the BLR of Mrk 817. These signatures indicate that the BLR of Keplerian motion in both AGNs seemingly has outflowing components during the monitoring period. We discuss the kinematics of the BLR and the measurements, including SMBH mass and accretion rates. [ABSTRACT FROM AUTHOR]

3C 273 is an intensively monitored flat-spectrum radio quasar with both a beamed jet and blue bump together with broad emission lines. The coexistence of the comparably prominent jet and accretion disk leads to complicated variability properties. Recent reverberation mapping monitoring for 3C 273 revealed that the optical continuum shows a distinct long-term trend that does not have a corresponding echo in the Hβ fluxes. We compile multiwavelength monitoring data from the Swift archive and other ground-based programs and clearly find two components of emissions at optical wavelength. One component stems from the accretion disk itself, and the other component can be ascribed to the jet contribution, which also naturally accounts for the nonechoed trend in reverberation mapping data. We develop an approach to decouple the optical emissions from the jet and accretion disk in 3C 273 with the aid of multiwavelength monitoring data. By assuming that the disk emission has a negligible polarization in consideration of the low inclination of the jet, the results show that the jet contributes a fraction of ∼10% at the minimum and up to ∼40% at the maximum to the total optical emissions. This is the first time to provide a physical interpretation of the "detrending" manipulation conventionally adopted in reverberation mapping analysis. Our work also illustrates the importance of appropriately analyzing variability properties in cases of coexisting jets and accretion disks. [ABSTRACT FROM AUTHOR]

We compiled a sample of 73 active galactic nuclei (AGNs) with reverberation mapping (RM) observations from RM campaigns, including our ongoing campaign of monitoring super-Eddington accreting massive black holes (BHs). This sample covers a large range of BH mass , dimensionless accretion rates , and 5100 Å luminosity , allowing us to systematically study the AGN variability and their relations with BH mass, accretion rates, and optical luminosity. We employed the damped random walk (DRW) model to delineate the optical variability of continuum at 5100 Å and obtained damped variability timescale () and amplitude () using a Markov Chain Monte Carlo method. We also estimated the traditional variability amplitudes (), which provide a model-independent measure and therefore are used to test the DRW results. We found that AGN variability characteristics are generally correlated with. These correlations are smooth from sub-Eddington to super-Eddington accretion AGNs, probably implying that the AGN variability may be caused by the same physical mechanism. [ABSTRACT FROM AUTHOR]