Donghoon Son

The lick AGN monitoring project 2011: Dynamical modeling of the broad-line region in Mrk 50

We present dynamical modeling of the broad-line region (BLR) in the Seyfert 1 galaxy Mrk 50 using reverberation mapping data taken as part of the Lick AGN Monitoring Project (LAMP) 2011. We model the reverberation mapping data directly, constraining the geometry and kinematics of the BLR, as well as deriving a black hole mass estimate that does not depend on a normalizing factor or virial coefficient. We find that the geometry of the BLR in Mrk 50 is a nearly face-on thick disk, with a mean radius of 9.6^(+1.2)_(–0.9) light days, a width of the BLR of 6.9^(+1.2)_(–1.1) light days, and a disk opening angle of 25 ± 10 deg above the plane. We also constrain the inclination angle to be 9^(+7)_(–5) deg, close to face-on. Finally, the black hole mass of Mrk 50 is inferred to be log_(10)(M_(BH)/M_☉) = 7.57^(+0.44)_(–0.27). By comparison to the virial black hole mass estimate from traditional reverberation mapping analysis, we find the normalizing constant (virial coefficient) to be log_(10) f = 0.78^(+0.44)_(–0.27), consistent with the commonly adopted mean value of 0.74 based on aligning the M_(BH)-σ* relation for active galactic nuclei and quiescent galaxies. While our dynamical model includes the possibility of a net inflow or outflow in the BLR, we cannot distinguish between these two scenarios.

The Lick AGN Monitoring Project 2011: Reverberation Mapping of Markarian 50

The Lick AGN Monitoring Project 2011 observing campaign was carried out over the course of 11 weeks in spring 2011. Here we present the first results from this program, a measurement of the broad-line reverberation lag in the Seyfert 1 galaxy Mrk 50. Combining our data with supplemental observations obtained prior to the start of the main observing campaign, our data set covers a total duration of 4.5 months. During this time, Mrk 50 was highly variable, exhibiting a maximum variability amplitude of a factor of ~4 in the U-band continuum and a factor of ~2 in the Hβ line. Using standard cross-correlation techniques, we find that Hβ and Hγ lag the V-band continuum by τ_(cen) = 10.64^(+0.82)_(–0.93) and 8.43^(+1.30)_(–1.28) days, respectively, while the lag of He II λ4686 is unresolved. The Hβ line exhibits a symmetric velocity-resolved reverberation signature with shorter lags in the high-velocity wings than in the line core, consistent with an origin in a broad-line region (BLR) dominated by orbital motion rather than infall or outflow. Assuming a virial normalization factor of f = 5.25, the virial estimate of the black hole mass is (3.2 ± 0.5) × 10^7 M_☉. These observations demonstrate that Mrk 50 is among the most promising nearby active galaxies for detailed investigations of BLR structure and dynamics.

The Prevalence of Gas Outflows in Type 2 AGNs

To constrain the nature and fraction of the ionized gas outflows in AGNs, we perform a detailed analysis on gas kinematics as manifested by the velocity dispersion and shift of the [O III] {\lambda}5007 emission line, using a large sample of ~39,000 type 2 AGNs at z<0.3. First, we confirm a broad correlation between [O III] and stellar velocity dispersions, indicating that the bulge gravitational potential plays a main role in determining the [O III] kinematics. However, [O III] velocity dispersion is on average larger than stellar velocity dispersion by a factor of 1.3-1.4 for AGNs with double Gaussian [O III], suggesting that the non-gravitational component, i.e., outflows, is almost comparable to the gravitational component. Second, the increase of the [O III] velocity dispersion (after normalized by stellar velocity dispersion) with both AGN luminosity and Eddington ratio suggests that non-gravitational kinematics are clearly linked to AGN accretion. The distribution in the [O III] velocity - velocity dispersion diagram dramatically expands toward large values with increasing AGN luminosity, implying that the launching velocity of gas outflows increases with AGN luminosity. Third, the majority of luminous AGNs presents the non-gravitational kinematics in the [O III] profile. These results suggest that ionized gas outflows are prevalent among type 2 AGNs. On the other hand, we find no strong trend of the [O III] kinematics with radio luminosity, once we remove the effect of the bulge gravitational potential, indicating that ionized gas outflows are not directly related to radio activity for the majority of type 2 AGNs.

Gait planning based on kinematics for a quadruped gecko model with redundancy

Recent research on mobile robots has focused on locomotion in various environments. In this paper, a gait-generation algorithm for a mobile robot that can travel from the ground to a wall and climb vertical surfaces is proposed. The algorithm was inspired by a gecko lizard. Our gait planning was based on inverse kinematics using the Jacobian of the whole body, where the redundancy was solved by defining an object function for the gecko posture to avoid collisions with the surface. The optimal scalar factor for these two objects was obtained by defining a superior object function to minimize the angular acceleration of joints. The algorithm was verified through simulation of the gecko model travelling on given task paths and avoiding abnormal joint movements and collisions.

Delayed or No Feedback? Gas Outflows in Type 2 AGNs. III

We present gas kinematics based on the [OIII]

ACCRETION PROPERTIES OF HIGH- AND LOW-EXCITATION YOUNG RADIO GALAXIES

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Design and Application of a Wire-Driven Bidirectional Telescopic Mechanism for Workspace Expansion with a Focus on Shipbuilding Tasks

5007 line and their connection to galaxy gravitational potential, active galactic nucleus (AGN) energetics, and star formation, using a large sample of ~110,000 AGNs and star-forming (SF) galaxies at z<0.3. Gas and stellar velocity dispersions are comparable to each other in SF galaxies, indicating that the ionized gas kinematics can be accounted by the gravitational potential of host galaxies. In contrast, AGNs clearly show non-gravitational kinematics, which is comparable to or stronger than the virial motion caused by the gravitational potential. The [OIII] velocity-velocity dispersion (VVD) diagram dramatically expands toward high values as a function of AGN luminosity, implying that the outflows are AGN-driven, while SF galaxies do not show such a trend. We find that the fraction of AGNs with a signature of outflow kinematics, steeply increases with AGN luminosity and Eddington ratio. In particular, the majority of luminous AGNs presents strong non-gravitational kinematics in the [OIII] profile. AGNs with strong outflow signatures show on average similar specific star formation rate (SSFR) to that of starforming galaxies. In contrast, AGNs with weak or no outflows have an order of magnitude lower SSFR, suggesting that AGNs with current strong outflows do now show any negative AGN feedback and that it may take the order of a dynamical time to impact on star formation over galactic scales.

Ionized-gas Kinematics Along the Large-scale Radio Jets in Type-2 AGNs

Young radio galaxies (YRGs) provide an ideal laboratory to explore the connection between the accretion disk and radio jet thanks to their recent jet formation. We investigate the relationship between the emission-line properties, the black hole accretion rate, and the radio properties using a sample of 34 low-redshift ( z< 0.4) YRGs. We classify YRGs as high-excitation galaxies (HEGs) and low-excitation galaxies (LEGs) based on the flux ratio of high-ionization to low-ionization emission lines. Using the Hα luminosities as a proxy of accretion rate, we find that HEGs in YRGs have ∼1 dex higher Eddington ratios than LEGs in YRGs, suggesting that HEGs have a higher mass accretion rate or higher radiative efficiency than LEGs. In agreement with previous studies, we find that the luminosities of emission lines, in particular Hα, are correlated with radio core luminosity, suggesting that accretion and young radio activities are fundamentally connected.

Development of a characteristic point detecting seam tracking algorithm for portable welding robots

Various products and patents have been established with regard to telescopic mechanisms over a long period of time. However, to the best of our knowledge, with reference to motional characteristics, few studies have been reported on a telescopic mechanism that is capable of bidirectional extension. Moreover, as we wish to point out here, such a kind of mechanism has received little attention due to the absence of practical applications. However, in the case of blast-cleaning and painting in double-hulled structures in shipbuilding, the bidirectional-extension mechanism seems to be a worthwhile subject for investigation since it will be of great help in the execution of suggested tasks for the entire transverse web floor with a range of 2–3 m. Since the self-traveling robotic platform is located on longitudinal stiffeners whose heights range from 400 to 800 mm, the manipulator to be installed on the robotic platform should have a bidirectional stroke to continuously approach the upper and lower sections of the transverse web floor. Further, with the rapid progress of the shipbuilding industry in South Korea, the importance of the bidirectional-extension mechanism in the automation of double-hulled structures has been increasingly recognized. Thus, for the design of a new mechanism, this paper describes a new type of telescopic mechanism that is capable of bidirectional strokes; the paper focuses on the mechanical design, analysis, manufacture and experimentation. Further, a customized pulley with a cylindrical-helix groove is designed to prevent the problem of overlapping steel wires since it leads to inaccurate position control with respect to the motors rotation. In particular, experiments have been conducted in terms of the positional repeatability of the manufactured telescopic manipulator and the quality of blast-cleaning of an upper section of a transverse web floor in a double-hulled structure. Throughout the experiments, the manufactured mechanism has demonstrated an amazing bidirectional translating stroke that has ranged from –500 to +2000 mm in field testing. Further, the repeatability of the manufactured bidirectional manipulator with the suggested motor–pulley system has been clearly identified as ±0.84 mm in the descending direction and ±0.63 mm in the ascending direction.

Stability of the Broad-line Region Geometry and Dynamics in Arp 151 over Seven Years

To investigate the connection between radioactivity and active galactic nucleus (AGN) outflows, we present a study of ionized-gas kinematics based on an [O iii] λ5007 emission line along the large-scale radio jet for six radio AGNs. These AGNs are selected based on the radioactivity (i.e., ) as well as optical emission-line properties as type-2 AGNs. Using the Red Channel Cross Dispersed Echellette Spectrograph at the Multiple Mirror Telescope, we investigate in detail the [[O iii]] and stellar kinematics. We spatially resolve and probe the central AGN-photoionization sizes, which is important in understanding the structures and evolutions of galaxies. We find that the typical central AGN-photoionization radius of our targets are in range of 0.9–1.6 kpc, consistent with the size–luminosity relation of [O iii] in previous studies. We investigate the [O iii] kinematics along the large-scale radio jets to test whether there is a link between gas outflows in the narrow-line region and extended radio-jet emissions. Contrary to our expectation, we find no evidence that the gas outflows are directly connected to the large-scale radio jets.