arXiv subjects

Huynh Anh N. Le

Publications and source records attributed to Huynh Anh N. Le.

At least 19 recordsLinked to original sources

arXiv2026

Discovery of four Narrow-line Type-1 Quasars at z = 2.54 -- 6.06 with Subaru 'Onohi'ula PFS-SSP

We report the discovery of four narrow-line type-1 quasars (NLQ1s) from the Subaru 'Onohi'ula Prime Focus Spectrograph Subaru Strategic Program (PFS-SSP). To extend a comprehensive understanding of this population to the distant universe, we searched for broad-line AGNs (quasars) whose rest-UV spectral shapes resemble those of local NLS1 galaxies, utilizing the Ly$α$ line profile. We identified four NLQ1s, including one candidate, at $z=2.54$ -- $6.06$. The obtained spectra show a prominent Ly$α$ emission line with a very low continuum level. The measured full width at half maximum (FWHM) of Ly$α$ ranges from $1410 \ \mathrm{km\,s^{-1}}$ to $1510 \ \mathrm{km\,s^{-1}}$ with a mean of $\sim 1430 \,\mathrm{km\,s^{-1}}$. Although we used only line width information for the NLQ1 selection, the resulting equivalent widths (EW) of Ly$α$ are higher (the mean $\sim 190$\,Å\ in the rest frame) than the typical values of quasars. Two quasars have exceptionally large Ly$α$ luminosity, accounting for $\sim 3$ -- $4$\% of the bolometric luminosity. We measured black hole masses and Eddington ratios for three objects whose C\,\textsc{iv} line is available. The resulting black hole masses are $\sim 10^{6.9}$ -- $10^{7.7}\, M_{\odot}$ with high Eddington ratios ($> 0.1$), consistent with those of NLS1 galaxies reported in the low-$z$ universe. N\,\textsc{v} and C\,\textsc{iv} broad absorption lines are detected in one object. This quasar can be classified as a mini-BAL quasar, which further supports the idea that this NLQ1 is indeed a luminous version of an NLS1 galaxy.

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arXiv2026

Active Galactic Nuclei and STaR fOrmation in Nearby Galaxies AGNSTRONG. III. A Study on Ionized and Warm Molecular Gas Outflows of 6 Type-2 AGNs

Active galactic nucleus (AGN)-driven gas outflows are one of the best tracers of AGN feedback in action, as these powerful outflows expel/heat or compress the surrounding interstellar medium (ISM), thus quenching or enhancing star-forming activity in their hosts. Studying the kinematics of outflows in different gas phases is crucial for comprehending how AGNs impact the ISM within their host galaxies. However, the differences in the physical natures of ionized and warm molecular gas outflows remain largely unexplored. To obtain a complete picture of AGN outflows and their feedback effects, we present a study of both ionized and warm molecular gas outflows in six type-2 AGNs ($z<0.1$) that exhibit strong ionized outflows in previous optical observations. Utilizing the Triple Spectrograph and Double Spectrograph instruments on the Palomar 200-inch Hale Telescope, we conduct spatially resolved measurements in the slit direction of strong emission lines from both ionized and warm molecular gas, such as $\rm [O\ III]$, $\rm Paα$, $\rm H_{2}$ 1-0 S(1), etc., allowing for a direct comparison of their outflow properties. One out of six AGNs shows significant ionized and warm molecular outflows in near-infrared bands, exhibiting the most powerful kinematics and highest luminosity. A positive correlation between the kinematics and AGN luminosity is shown, suggesting that more luminous AGNs, which reflect higher levels of AGN activity, tend to have a greater impact on the gases, probably driving the outflows.

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arXiv2026

Active Galactic Nuclei and STaR fOrmation in Nearby Galaxies (AGNSTRONG). II: Results for Jetted Type-I AGNs with Strong Ionized Gas Outflows

We investigate the correlation between ionized gas outflows, jets, and star formation in a sample of 42 local type-I active galactic nuclei (AGNs) exhibiting significant [O III] outflows. This study uses both new submillimeter (sub-mm) observations and archival data from the James Clerk Maxwell Telescope. Our analysis, which includes a correction for jet emission in the sub-mm bands, fitting spectral energy distribution, and analyzing spectra, enables us to derive star-formation rates (SFRs) through various methods. By comparing radio power and SFRs, we select a sub-sample of jetted AGNs of which radio emission is mostly from the jets. We find that jetted AGNs predominantly lie above the main sequence of star-forming galaxies, suggesting a correlation between jet activity and star formation. By comparing dust extinction, we demonstrate that jetted AGNs do not have more dust which is the fuel of both star formation and AGN activity. Therefore, this correlation is more likely to arise from AGN feedback. We also find that the Eddington ratio does not impact the specific SFRs (sSFRs) of our sample. Additionally, for jetted AGNs, stronger radio emission corresponds to higher sSFRs, suggesting that jet emission may promote star formation, i.e., positive feedback. Our results not only shed light on the feedback mechanisms of AGNs but also underscore the complex interplay between black hole activity and star formation in galaxy evolution.

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arXiv2025

A Comparison of Star Formation Rates by Different Tracers in Nearby Galaxies

We utilize a large sample of $\sim$113,000 galaxies ($z < 0.3$) from the Sloan Digital Sky Survey with high-quality data to compare star formation rates (SFRs) across multiple diagnostic methods and examine their connection to Active Galactic Nuclei (AGNs) strength, indicated by Eddington ratio. Our sample encompassed star-forming (SF), composite, Seyfert, and LINER galaxies. Our analysis utilizes various SFRs indicators, including observed infrared flux ($\rm SFR_{FIR}$) from AKARI/Herschel ($\sim$4,100 sources), the MPA-JHU catalog ($\rm SFR_{Dn4000}$), the ANN catalog ($\rm SFR_{ANN}$), the GSWLC catalog ($\rm SFR_{SED}$ and $\rm SFR_{MIR}$), as well as \OII\ and \Ha\ emission lines ($\rm SFR_{[OII]}$ and $\rm SFR_{Hα}$). Within SF galaxies, SFRs measurements from different tracers exhibited differences, with offsets and scatter below 0.26 dex and 0.29 dex, respectively. Moreover, non-SF galaxies (composite, Seyfert, and LINER) displayed discrepancies among SFR tracers, particularly for LINER galaxies, with offsets below 0.86 dex and a scatter of 0.57 dex. Additionally, our findings revealed robust correlations between SFRs and specific SFRs (sSFRs) with Eddington ratios. Eddington ratio exhibited gradual transitions in the (s)SFRs-stellar mass diagrams. Galaxies with high Eddington ratios displayed high star formation activity, similar to blue SF galaxies. Furthermore, we observed decreasing sSFR trends from SF galaxies to composite, Seyfert, and LINER galaxies. Our results may provide insight into our understanding of (s)SFRs traced by different approaches and their connection to AGN activities.

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arXiv2025

10 Years of Archival High-Resolution NIR Spectra: The Raw and Reduced IGRINS Spectral Archive (RRISA)

The Immersion GRating INfrared Spectrometer (IGRINS) is a compact, high-resolution (R~45,000) near-infrared spectrograph spanning 1.45 to 2.45 um in a single exposure. We introduce the Raw and Reduced IGRINS Spectral Archive (RRISA), which provides public data access for all non-proprietary IGRINS data taken at McDonald Observatory's Harlan J. Smith Telescope, the Lowell Discovery Telescope (formerly Discovery Channel Telescope), and Gemini South. RRISA provides access to raw files, reduced data products, and cross-matched IGRINS targets with the SIMBAD, 2MASS, Gaia DR3, APOGEE2 DR17, and PASTEL catalogs. We also introduce version 3 of the IGRINS data reduction pipeline, IGRINS PLP v3, which implements an improved cosmic ray correction, pattern noise removal, and a new flexure correction that reduces telluric residuals. RRISA and supporting information can be found at http://igrinscontact.github.io.

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arXiv2024

Nuclear and Star Formation Activities in Nearby Galaxies: Roles of Gas Supply and AGN Feedback

We analyzed a sample of $\sim$113,000 galaxies ($\rm z < 0.3$) from the Sloan Digital Sky Survey, divided into star-forming, composite, Seyfert, and LINER types, to explore the relationships between UV-to-optical colors ($\rm u-r$), star formation rates (SFRs), specific star formation rates (sSFRs), stellar velocity dispersions ($\rm σ_{*}$), mass accretion rates onto the black hole ($\rm L_{[OIII]}/σ_{*}^{4}$), and Eddington ratios. Star-forming galaxies predominantly feature young, blue stars along the main-sequence (MS) line, while composite, Seyfert, and LINER galaxies deviate from this line, displaying progressively older stellar populations and lower SFRs. $\rm L_{[OIII]}/σ_{*}^{4}$ and Eddington ratios are highest in Seyfert galaxies, moderate in composite galaxies, and lowest in LINERs, with higher ratios associated with bluer colors, indicating a younger stellar population and stronger active galactic nucleus (AGN) activity. These trends suggest a strong correlation between sSFRs and Eddington ratios, highlighting a close connection between AGN and star formation activities. These results may imply an evolutionary sequence where galaxies transition from blue star-forming galaxies to red LINERs, passing through composite and Seyfert phases, driven primarily by gas supply, with AGN feedback playing a secondary role. While both radio luminosities ($\rm L_{1.4GHz}$) and Eddington ratios correlate with SFRs, their trends differ on the SFR$-$stellar mass ($\rm M_{*}$) plane, with radio luminosities increasing with stellar mass along the MS line, and no direct connection between radio luminosities and Eddington ratios. These findings may provide new insights into the interplay between star formation, AGN activity, and radio emission in galaxies, shedding light on their evolutionary pathways.

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arXiv2024

Active Galactic Nuclei and STaR fOrmation in Nearby Galaxies (AGNSTRONG). I. Sample and Strategy

We introduce our project, AGNSTRONG (Active Galactic Nuclei and STaR fOrmation in Nearby Galaxies). Our research goals encompass investigating the kinematic properties of ionized and molecular gas outflows, understanding the impact of AGN feedback, and exploring the coevolution dynamics between AGN strength activity and star formation activity. We aim to conduct a thorough analysis to determine whether there is an increase or suppression in SFRs among targets with and without powerful relativistic jets. Our sample consists of 35 nearby AGNs with and without powerful relativistic jet detections. Utilizing sub-millimeter (sub-mm) continuum observations at 450 μm and 850 μm from SCUBA-2 at the James Clerk Maxwell Telescope, we determine star-formation rates (SFRs) for our sources using spectral energy distribution (SED) fitting models. Additionally, we employ high-quality, spatially resolved spectra from UV-optical to near-infrared bands obtained with the Double Spectrograph and Triple Spectrograph mounted on the 200-inch Hale telescope at Palomar Observatory to study their multiphase gas outflow properties. This paper presents an overview of our sample selection methodology, research strategy, and initial results of our project. We find that the SFRs determined without including the sub-mm data in the SED fitting are overestimated by approximately 0.08 dex compared to those estimated with the inclusion of sub-mm data. Additionally, we compare the estimated SFRs in our work with those traced by the 4000Å break, as provided by the MPA-JHU catalog. We find that our determined SFRs are systematically higher than those traced by the 4000Å break. Finally, we outline our future research plans.

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arXiv2023

The Seoul National University AGN Monitoring Project III: H$β$ lag measurements of 32 luminous AGNs and the high-luminosity end of the size--luminosity relation

We present the main results from a long-term reverberation mapping campaign carried out for the Seoul National University Active Galactic Nuclei (AGN) Monitoring Project. High-quality data were obtained during 2015-2021 for 32 luminous AGNs (i.e., continuum luminosity in the range of $10^{44-46}$ erg s$^{-1}$) at a regular cadence, of 20-30 days for spectroscopy and 3-5 days for photometry. We obtain time lag measurements between the variability in the H$β$ emission and the continuum for 32 AGNs; twenty-five of those have the best lag measurements based on our quality assessment, examining correlation strength, and the posterior lag distribution. Our study significantly increases the current sample of reverberation-mapped AGNs, particularly at the moderate to high luminosity end. Combining our results with literature measurements, we derive a H$β$ broad line region size--luminosity relation with a shallower slope than reported in the literature. For a given luminosity, most of our measured lags are shorter than the expectation, implying that single-epoch black hole mass estimators based on previous calibrations could suffer large systematic uncertainties.

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arXiv2023

Unraveling the Complex Structure of AGN-driven Outflows. VI. Strong Ionized Outflows in Type 1 AGNs and the Outflow Size-Luminosity Relation

We present spatially resolved gas kinematics, ionization, and energetics of 11 type 1 and 5 type 2 active galactic nuclei (AGNs) with strong ionized gas outflows at z $<0.3$ using Gemini Multi-Object Spectrograph Integral Field Unit (GMOS-IFU) data. We find a strongly blueshifted region in [OIII] velocity maps, representing an approaching cone in biconical outflows, and blueshifted and redshifted regions in H$α$ velocity maps, which show gravitationally rotating kinematics. AGN photoionization is dominant in the central region of most targets, and some of them also show ring-like structures of LINER or composite that surround the AGN-dominated center. Following our previous studies, we kinematically determine outflow sizes by the ratio between [OIII] and stellar velocity dispersion. Outflow sizes of type 1 AGNs follow the same kinematic outflow size-[OIII] luminosity relation obtained from the type 2 IFU sample in Kang & Woo and Luo (updated slope $0.29\pm0.04$), while they are limited to the central kpc scales, indicating the lack of global impact of outflows on the interstellar medium. Small mass outflow rates and large star formation rates of the combined sample support that there is no evidence of rapid star formation quenching by outflows, which is consistent with the delayed AGN feedback.

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arXiv2023

A preliminary study of photometric redshifts based on the Wide Field Survey Telescope

The Wide Field Survey Telescope (WFST) is a dedicated time-domain multi-band ($u$, $g$, $r$, $i$, and $z$) photometric survey facility under construction. In this paper, we present a preliminary study that assesses the quality of photometric redshifts based on WFST by utilizing mock observations derived with the galaxy catalog in the COSMOS/UltraVISTA field. We apply the template fitting technique to estimate photometric redshifts by using the ZEBRA photometric-redshift code and adopting a modified set of adaptive templates. We evaluate the bias (median relative offset between the output photometric redshifts and input redshifts), normalized median absolute deviation ($σ_{\rm NMAD}$) and outlier fraction ($f_{\rm outlier}$) of photometric redshifts in two typical WFST observational cases, the single 30-second exposure observations (hereafter shallow mode) and co-added 50-minute exposure observations (hereafter deep mode). We find bias$\la0.006$, $σ_{\rm NMAD}\la0.03$, and $f_{\rm outlier}\la5\%$ in the shallow mode and bias$\approx 0.005$, $σ_{\rm NMAD}\approx 0.06$, and $f_{\rm outlier}\approx 17\%$--$27\%$ in the deep mode, respectively, under various lunar phases. Combining the WFST mock observational data with that from the upcoming CSST and Euclid surveys, we demonstrate that the $z_{\rm phot}$ results can be significantly improved, with $f_{\rm outlier}\approx 1\%$ and $σ_{\rm NMAD}\approx 0.02$.

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arXiv2023

The Seoul National University AGN Monitoring Project IV: H$α$ reverberation mapping of 6 AGNs and the H$α$ Size-Luminosity Relation

The broad line region (BLR) size-luminosity relation has paramount importance for estimating the mass of black holes in active galactic nuclei (AGNs). Traditionally, the size of the H$β$ BLR is often estimated from the optical continuum luminosity at 5100\angstrom{} , while the size of the H$α$ BLR and its correlation with the luminosity is much less constrained. As a part of the Seoul National University AGN Monitoring Project (SAMP) which provides six-year photometric and spectroscopic monitoring data, we present our measurements of the H$α$ lags of 6 high-luminosity AGNs. Combined with the measurements for 42 AGNs from the literature, we derive the size-luminosity relations of H$α$ BLR against broad H$α$ and 5100\angstrom{} continuum luminosities. We find the slope of the relations to be $0.61\pm0.04$ and $0.59\pm0.04$, respectively, which are consistent with the \hb{} size-luminosity relation. Moreover, we find a linear relation between the 5100\angstrom{} continuum luminosity and the broad H$α$ luminosity across 7 orders of magnitude. Using these results, we propose a new virial mass estimator based on the H$α$ broad emission line, finding that the previous mass estimates based on the scaling relations in the literature are overestimated by up to 0.7 dex at masses lower than $10^7$~M$_{\odot}$.

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arXiv2023

[OIII] 5007A Emission Line Width as a Surrogate for stellar dispersion in Type 1 AGNs?

We present a study of the relation between the [OIII] 5007A emission line width (sigma_{[OIII]}) and stellar velocity dispersion (sigma_{*}), utilizing a sample of 740 type 1 active galactic nuclei (AGNs) with high-quality spectra at redshift z < 1.0. We find the broad correlation between the core component of [OIII] emission line width (sigma_{[OIII,core]}) and sigma_{*} with a scatter of 0.11~dex for the low redshift (z < 0.1) sample; for redshift (0.3 < z < 1.0) AGNs, the scatter is larger, being 0.16~dex. We also find that the Eddington ratio (L_{bol}/L_{Edd}) may play an important role in the discrepancies between sigma_{[OIII,core]} and sigma_{*}. As the L_{bol}/L_{Edd} increases, sigma_{[OIII,core]} tends to be larger than sigma_{*}. By classifying our local sample with different minor-to-major axis ratios, we find that sigma_{*} is larger than sigma_{[OIII,core]} for those edge-on spiral galaxies. In addition, we also find that the effects of outflow strength properties such as maximum outflow velocity (V_{max}) and the broader component of [OIII] emission line width and line shift (sigma_{[OIII,out]} and V_{[OIII,out]}) may play a major role in the discrepancies between sigma_{[OIII,core]} and sigma_{*}. The discrepancies between sigma_{[OIII,core]} and sigma_{*} are larger when V_{max}, V_{[OIII,out]}, and sigma_{[OIII,out]} increase. Our results show that the outflow strengths may have significant effects on the differences between narrow-line region gas and stellar kinematics in AGNs. We suggest that caution should be taken when using sigma_{[OIII,core]} as a surrogate for sigma_{*}. In addition, the substitute of sigma_{[OIII,core]} for sigma_{*} could be used only for low luminosity AGNs.

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arXiv2021

AGN lifetimes in UV-selected galaxies: a clue to supermassive black hole-host galaxy coevolution

The coevolution between supermassive black holes (SMBHs) and their host galaxies has been proposed for more than a decade, albeit with little direct evidence about black hole accretion activities regulating galaxy star formation at $z>1$. In this paper, we study the lifetimes of X-ray active galactic nuclei (AGNs) in $UV$-selected red sequence (RS), blue cloud (BC) and green valley (GV) galaxies, finding that AGN accretion activities are most prominent in GV galaxies at $z\sim1.5-2$, compared with RS and BC galaxies. We also compare AGN accretion timescales with typical color transition timescales of $UV$-selected galaxies. We find that the lifetime of GV galaxies at $z\sim1.5-2$ is very close to the typical timescale when the AGNs residing in them stay in the high-accretion-rate mode at these redshifts; for BC galaxies, the consistency between the color transition timescale and the black hole strong accretion lifetime is more likely to happen at lower redshifts ($z<1$). Our results support the scenario where AGN accretion activities govern $UV$ color transitions of host galaxies, making galaxies and their central SMBHs coevolve with each other.

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arXiv2020

Calibrating Mg II-based black-hole mass estimators using Low-to-High-Luminosity Active Galactic Nuclei

We present single-epoch black-hole mass (\mbh) estimators based on the rest-frame ultraviolet (UV) \MgII\ 2798Å and optical \Hb\ 4861Å emission lines. To enlarge the luminosity range of active galactic nuclei (AGNs), we combine the 31 reverberation-mapped AGNs with relatively low luminosities from Bahk et al. 2019, 47 moderate-luminosity AGNs from Woo et al. 2018, and 425 high-luminosity AGNs from the Sloan Digital Sky Survey (SDSS). The combined sample has the monochromatic luminosity at 5100Å ranging $\mathrm{\log λL_{5100} \sim 41.3-46.5}$ \ergs, over the range of 5.5 $<$ $\log$\mbh\ $<$ 9.5. Based on the fiducial mass from the line dispersion or full width half maximum (FWHM) of \Hb\ paired with continuum luminosity at 5100Å, we calibrate the best-fit parameters in the black hole mass estimators using the \MgII\ line. We find that the differences in the line profiles between \MgII\ and \Hb\ have significant effects on calibrating the UV \mbh\ estimators. By exploring the systematic discrepancy between the UV and optical \mbh\ estimators as a function of AGN properties, we suggest to add correction term $Δ$M = -1.14 $\rm \log(FWHM_{MgII}/σ_{MgII}$) + 0.33 in the UV mass estimator equation. We also find a $\sim$0.1 dex bias in the \mbh\ estimation due to the difference of the spectral slope in the 2800-5200 Å range. Depending on the selection of \mbh\ estimator based on either line dispersion or FWHM and either continuum or line luminosity, the derived UV mass estimators show >~0.1 dex intrinsic scatter with respect to the fiducial \Hb\ based \mbh.

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arXiv2020

Variability and the size-luminosity relation of the intermediate mass AGN in NGC 4395

We present the variability study of the lowest-luminosity Seyfert 1 galaxy NGC 4395 based on the photometric monitoring campaigns in 2017 and 2018. Using 22 ground-based and space telescopes, we monitored NGC 4395 with a $\sim$5 minute cadence during a period of 10 days and obtained light curves in the UV, V, J, H, and K/Ks bands as well as the H$α$ narrow-band. The RMS variability is $\sim$0.13 mag on \emph{Swift}-UVM2 and V filter light curves, decreasing down to $\sim$0.01 mag on K filter. After correcting for continuum contribution to the H$α$ narrow-band, we measured the time lag of the H$α$ emission line with respect to the V-band continuum as ${55}^{+27}_{-31}$ to ${122}^{+33}_{-67}$ min. in 2017 and ${49}^{+15}_{-14}$ to ${83}^{+13}_{-14}$ min. in 2018, depending on the assumption on the continuum variability amplitude in the H$α$ narrow-band. We obtained no reliable measurements for the continuum-to-continuum lag between UV and V bands and among near-IR bands, due to the large flux uncertainty of UV observations and the limited time baseline. We determined the AGN monochromatic luminosity at 5100Å $λL_λ= \left(5.75\pm0.40\right)\times 10^{39}\,\mathrm{erg\,s^{-1}}$, after subtracting the contribution of the nuclear star cluster. While the optical luminosity of NGC 4395 is two orders of magnitude lower than that of other reverberation-mapped AGNs, NGC 4395 follows the size-luminosity relation, albeit with an offset of 0.48 dex ($\geq$2.5$σ$) from the previous best-fit relation of Bentz et al. (2013).

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arXiv2020

IGRINS Slit-Viewing Camera Software

We have developed observation control software for the Immersion GRating INfrared Spectrometer (IGRINS) slit-viewing camera module, which maintains the position of an astronomical target on the spectroscopic slit. It is composed of several packages that monitor and control the system, acquire the images, and compensate for the tracking error by sending tracking feedback information to the telescope control system. For efficient development and maintenance of each software package, we have applied software engineering methods, i.e., a spiral software development with model-based design. It is not trivial to define the shape and center of astronomical object point spread functions (PSFs), which do not have symmetric Gaussian profiles in short exposure (<4 s) guiding images. Efforts to determine the PSF centroid are additionally complicated by the core saturation of bright guide stars. We have applied both a two-dimensional Gaussian fitting algorithm (2DGA) and center balancing algorithm (CBA) to identify an appropriate method for IGRINS in the near-infrared K-band. The CBA derives the expected center position along the slit-width by referencing the spillover flux ratio of the PSF wings on both sides of the slit. In this research, we have compared the accuracy and reliability of the CBA to the 2DGA by using data from IGRINS commissioning observations at McDonald Observatory. We find that the performance of each algorithm depends on the brightness of the targets and the seeing conditions, with the CBA performing better in typical observing scenarios. The algorithms and test results we present can be utilized with future spectroscopic slit observations in various observing conditions and for a variety of spectrograph designs.

astro-ph.IM↗

arXiv2019

Comparison of The UV and Optical Fe II Emission in Type 1 AGNs

We present the kinematical properties of the UV and optical \FeII\ emission gas based on the velocity shift and line width measurements of a sample of 223 Type 1 active galactic nuclei (AGNs) at 0.4 $<$ z $<$ 0.8. We find a strong correlation between the line widths of the UV and optical \FeII\ emission lines, indicating that both \FeII\ emission features arise from similar distances in the broad line region (BLR). However, in detail we find differing trends, depending on the width of \FeII. While the velocity shifts and dispersions of the UV Fe II (\FeUV) and optical Fe II (\FeOPT) emission lines are comparable to each other for AGNs with relatively narrow \FeOPT\ line widths (i.e., FWHM < 3200 \kms; Group A), \FeOPT\ is broader than \FeUV\ for AGNs with relatively broad \FeOPT\ (i.e., FWHM > 3200 \kms; Group B). \FeII\ emission lines are on average narrower than \Hb\ and \MgII\ for Group A, indicating the \FeII\ emission region is further out in the BLR, while for Group B AGNs \FeOPT\ is comparable to \Hb\ and broader than \MgII. While \FeII\ emission lines are on average redshifted ($40\pm141$ \kms\ and $182\pm95$, respectively for \FeUV\ and \FeOPT), indicating inflow, the sample as a whole shows a large range of velocity shifts, suggesting complex nature of gas kinematics.

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arXiv2019

The Seoul National University AGN monitoring project. II. BLR size and black hole mass of two AGNs

Active galactic nuclei (AGNs) show a correlation between the size of the broad line region (BLR) and the monochromatic continuum luminosity at 5100 Å, allowing black hole mass estimation based on single-epoch spectra. However, the validity of the correlation is yet to be clearly tested for high-luminosity AGNs. We present the first reverberation-mapping results of the Seoul National University AGN monitoring program (SAMP), which is designed to focus on luminous AGNs for probing the high end of the size-luminosity relation. We report time lag measurements of two AGNs, namely, 2MASS J10261389+5237510 and SDSS J161911.24+501109.2, using the light curves obtained over a $\sim$1000 day period with an average cadence of $\sim$10 and $\sim$20 days, respectively for photometry and spectroscopy monitoring. Based on a cross-correlation analysis and H$β$ line width measurements, we determine the H$β$ lag as $41.8^{+4.9}_{-6.0}$ and $52.6^{+17.6}_{-14.7}$ days in the observed-frame, and black hole mass as $3.65^{+0.49}_{-0.57} \times 10^7 M_{\odot}$ and $23.02^{+7.81}_{-6.56} \times 10^7 M_{\odot}$, respectively for 2MASS J1026 and SDSS J1619.

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