Velocity Dispersion σ_(aper)Aperture Corrections as a Function of Galaxy Properties from Integral-field Stellar Kinematics of 10,000 MaNGA Galaxies

The second moment of the stellar velocity within the effective radius,denoted by σ^(2)_(e),is a crucial quantity in galaxy studies,as it provides insight into galaxy properties and their mass distributions.However,large spectroscopic surveys typically do not measure σ_(e) directly,instead providing σ_(aper),the second moment of the stellar velocity within a fixed fiber aperture.In this paper,we derive an empirical aperture correction formula,given byσ_(aper)/σ_(e)=(R_(aper)/R_(e))^(α),using spatially resolved stellar kinematics extracted from approximately 10,000 Sloan Digital Sky Survey-Mapping Nearby Galaxies at Apache Point Observatory integral field unit observations.Our analysis reveals a strong dependence ofαon the r-band absolute magnitude M_(r),g-i color,and Sérsic index nSer,whereαvalues are lower for brighter,redder galaxies with higher Sérsic indices.Our results demonstrate that the aperture correction derived from previous literature on early-type galaxies cannot be applied to predict the aperture corrections for galaxies with intermediate Sérsic indices.We provide a lookup table ofαvalues for different galaxy types,with parameters in the ranges of-18>M_(r)>-24,0.4<g-i<1.6,and 0<n_(Ser)<8.A Python script is provided to obtain the correction factors from the lookup table.

Cross-method Analysis of Corotation Radii Data Set for Spiral Galaxies

A corotation radius is a key characteristic of disk galaxies that is essential to determine the angular speed of the spiral structureΩ_p,and therefore understand its nature.In the literature,there are plenty of methods to estimate this value,but do these measurements have any consistency?In this work,we collected a data set of corotation radius measurements for 547 galaxies,300 of which had at least two values.An initial analysis reveals that most objects have rather inconsistent corotation radius positions.Moreover,a significant fraction of galactic disks is distinguished by a large error coverage and almost uniform distribution of measurements.These findings do not have any relation to spiral type,Hubble classification,or presence of a bar.Among other reasons,obtained results could be explained by the transient nature of spirals in a considerable part of galaxies.We have made our collected data sample publicly available,and have demonstrated on one example how it could be useful for future research by investigating a winding time value for a sample of galaxies with possible multiple spiral arm patterns.

Kinematics and dynamics analysis of a 3-7R parallel decoupling mechanism

One kind of movable-pair analysis method is adopted to analyze the configuration of a 3-7R （revolute-pair） parallel decoupling mechanism, and the mechanism＇s characteristics are summarized. The mechanism has three orthogonal distributional branch-chains, and all movable pairs are rotational joints. The movable platform of the mechanism has x, y, z translational decoupling directions. Furthermore, in order to verify the mechanism＇s decoupling characteristics, the mechanism＇s kinematics analysis is solved, and the mechanism＇s direct/inverse kinematics model, input/output velocities and accelerations are deduced, which confirm its decoupling movement characteristics. Finally, one kind of mechanism link decomposed-integrated approach is adopted, and the mechanism＇s dynamics model is completed with the Lagrange method, which also proves its decoupling force characteristics. All of these works provide significant theory for the further study of the mechanism＇s control strategy, design, path planning etc.

Modeling the Newtonian dynamics for rotation curve analysis of thin-disk galaxies

We present an efficient, robust computational method for modeling the Newtonian dynamics for rotation curve analysis of thin-disk galaxies. With appropriate mathematical treatments, the apparent numerical difficulties associated with singularities in computing elliptic integrals are completely removed. Using a boundary element discretization procedure, the governing equations are transformed into a linear algebra matrix equation that can be solved by straightforward Gauss elimination in one step without further iterations. The numerical code implemented according to our algorithm can accurately determine the surface mass density distribution in a disk galaxy from a measured rotation curve （or vice versa）. For a disk galaxy with a typical flat rotation curve, our modeling results show that the surface mass density monotonically decreases from the galactic center toward the periphery, according to Newtonian dynamics. In a large portion of the galaxy, the surface mass density follows an approximately exponential law of decay with respect to the galactic radial coordinate. Yet the radial scale length for the surface mass density seems to be generally larger than that of the measured brightness distribution, suggesting an increasing mass-tolight ratio with the radial distance in a disk galaxy. In a nondimensionalized form, our mathematical system contains a dimensionless parameter which we call the ＂galactic rotation number＂ that represents the gross ratio of centrifugal force and gravitational force. The value of this galactic rotation number is determined as part of the numerial solution. Through a systematic computational analysis, we have illustrated that the galactic rotation number remains within 4-10% of 1.70 for a wide variety of rotation curves. This implies that the total mass in a disk galaxy is proportional to V02 Rg, with V0 denoting the characteristic rotation velocity （such as the ＂flat＂ value in a typical ro- tation curve） and Rg the radius of the galactic disk. The predicted total galactic mass of the Milky Way is in good agreement with the star-count data.

Similarity of jet radiation between flat spectrum radio quasars and GeV narrow-line Seyfert 1 galaxies: a universal δ-Lc correlation

By modeling the broadband spectral energy distributions （SEDs） of a typical flat spectrum radio quasar （FSRQ, 3C 279） and two GeV narrow-line Seyfert 1 galaxies （NLSls, PMN J0948＋0022 and 1H 0323＋342） in different flux stages with one-zone leptonic models, we find a universal correlation between their Doppler factors （δ） and peak luminosities （Lc） of external Compton scattering bumps. Compiling a combined sample of FSRQs and GeV NLSls, it is found that both FSRQs and GeV NLSls in different stages and in different sources follow the same δ-Lc correlation well. This indicates that the variations of observed luminosities may be essentially due to the Doppler boosting effect. The universal δ-Lo relation between FSRQs and GeV NLS 1 s in different stages may be further evidence that the particle acceleration and radiation mechanisms for the two kinds of sources are similar. In addition, by replacing Lc with the observed luminosity in the Fermi/LAT band （LLAT）, this correlation holds and it may serve as an empirical indicator of δ. We estimate the δ values with LLAT for 484 FSRQs in the Fermi/LAT Catalog and they range from 3 to 41, with a median of 16, which are statistically consistent with the values derived by other methods.

A Fermi-LAT Study of Globular Cluster Dynamical Evolution in the Milky Way:Millisecond Pulsars as the Probe

Using archival Fermi-LAT data with a time span of~12 yr,we study the population of Millisecond Pulsars(MSPs)in Globular Clusters(GlCs)and investigate their dependence on cluster dynamical evolution in the Milky Way.We show that theγ-ray luminosity(L_(γ))and emissivity(i.e.,ε_(γ)=L_(γ)/M,with M the cluster mass)are good indicators of the population and abundance of MSPs in GlCs,and they are highly dependent on the dynamical evolution history of the host clusters.Specifically speaking,the dynamically older GlCs with more compact structures are more likely to have larger L_(γ)andε_(γ),and these trends can be summarized as strong correlations with cluster stellar encounter rateΓand the specific encounter rate(Λ=Γ/M),with L_(γ)∝Γ^(0.7±0.11)andε_(γ)∝Λ^(0.73±0.13)for dynamically normal GlCs.However,as GlCs evolve into deep core collapse,these trends are found to be reversed,implying that strong encounters may have lead to the disruption of Low-Mass X-ray Binaries and ejection of MSPs from core-collapsed systems.Besides,the GlCs are found to exhibit largerε_(γ)with increasing stellar mass function slope(ε_(γ)∝10^((0.52±0.1)α)),decreasing tidal radius(ε_(γ)∝R_(t)^(-10±0.22))and distances from the Galactic Center(GC,ε_(γ)∝R_(gc)^(-1.13±0.21)).These correlations indicate that,as GlCs losing kinetic energy and spiral in toward the GC,tidal stripping and mass segregation have a preference in leading to the loss of normal stars from GlCs,while MSPs are more likely to concentrate to cluster center and be deposited into the GC.Moreover,we gaugeε_(γ)of GlCs is~10-1000 times larger than the Galactic bulge,the latter is thought to reside thousands of unresolved MSPs and may be responsible for the GC 7-ray excess,which supports that GlCs are generous contributors to the population of MSPs in the GC.

Revisiting the dichotomy of early-type galaxies

We study the relationship between isophotal shapes, central light profiles and kinematic properties of early-type galaxies （ETGs） based on a compiled sample of 184 ETGs. These sample galaxies are included in Data Release 8 of the Sloan Digital Sky Survey and have central light profiles and kinematic properties available from the literature, which were compiled from observations by the Hubble Space Telescope and the ATLAS3D integral-field spectrograph, respectively. We find that there is only a weak correlation between the isophotal shape （a4/a） and the central light profile （within 1 kpc） of ETGs. About two-fifths of ＂core＂ galaxies have disky isophotes, and one-third of ＂power-law＂ galaxies are boxy. Our statistical results also show that there are weak correlations between galaxy luminosity and dynamical mass with a4/a, but such correlations are tighter with a central light profile. Moreover, no clear link has been found between the isophotal shape and the Sersic index. Comparisons show that there are similar correlations between a4/a and ellipticity, and between a4/a and specific angular momentum ARo/2 for ＂power-law＂ ETGs, but there are no such correlations for ＂core＂ ETGs. Therefore, we speculate that the bimodal classifications of ETGs are not as simple as previously thought, though we also find that the disky ETGs with highest a4/a are more elongated and fast rotators.

Observation of Complex Organic Molecules Containing Peptide-like Bonds Toward Hot Core G358.93-0.03 MM1

In star formation regions,the complex organic molecules(COMs)that contain peptide bonds(-NH-C(=O)-)play a major role in the metabolic process because-NH-C(=O)-is connected to amino acids(R-CHNH_2-COOH).Over the past few decades,many COMs containing peptide-like bonds have been detected in hot molecular cores(HMCs),hot corinos,and cold molecular clouds,however,their prebiotic chemistry is poorly understood.We present the first detection of the rotational emission lines of formamide(NH_2CHO)and isocyanic acid(HNCO),which contain peptide-like bonds toward the chemically rich HMC G358.93-0.03 MM1,using high-resolution and high-sensitivity Atacama Large Millimeter/submillimeter Array bands 6 and 7.We estimate that the column densities of NH_2CHO and HNCO toward G358.93-0.03 MM1 are(2.80±0.29)×10~(15)cm~(-2)and(1.80±0.42)×10~(16)cm~(-2)with excitation temperatures of 165±21 K and 170±32 K,respectively.The fractional abundances of NH_2CHO and HNCO toward G358.93-0.03 MM1 are(9.03±1.44)×10~(-10)and(5.80±2.09)×10^(-9).We compare the estimated abundances of NH_2CHO and HNCO with the existing threephase warm-up chemical model abundance values and notice that the observed and modeled abundances are very close.We conclude that NH_2CHO is produced by the reaction of NH_2and H_2CO in the gas phase toward G358.93-0.03 MM1.Likewise,HNCO is produced on the surface of grains by the reaction of NH and CO toward G358.93-0.03 MM1.We also find that NH_2CHO and HNCO are chemically linked toward G358.93-0.03 MM1.

Gaseous versus Stellar Velocity Dispersion in Emission-Line Galaxies

We compare the ionized gas velocity dispersion σgas with the stellar velocity dispersion σ＊ in star-forming galaxies, composite galaxies, Low Ionization Nuclear Emissionline Regions （LINERs） and Seyfert 2s, compiled from a cross-identification of Sloan Digital Sky Survey Fourth Data Release （SDSS DR4） and Point Source Catalogue Redshift Survey （PSCz）. We measure σgas from the FWHMs of emission lines （Hα, [NⅡ]λλ6548, 6583 and [SⅡ]λλ6716, 6731）. A significant correlation between the gas and stellar velocity dispersion exists, despite substantial scatter. The mean value of the gas to stellar velocity dispersion ratio is close to unity. This suggests that gas velocity dispersion can substitute for the stellar velocity dispersion as a tracer of the gravitational potential well for all the four types of galaxies, but the involved uncertainties are different from type to type. We also studied -↑σgas, as a function of the redshift and the axial ratio to test the effects of aperture and galaxy inclination, and found that both effects are weak. Finally we checked the trend of -↑σgas/σ＊ with the infrared luminosity and found no significant correlation.

Stellar dynamical modeling-accuracy of 3D density estimation for edge-on axisymmetric galaxies

From Rybicki’s analysis using the Fourier slice theorem,mathematically it is possible to reproduce uniquely an edge-on axisymmetric galaxy’s 3D light distribution from its 2D surface brightness.Utilizing galaxies from a cosmological simulation,we examine the ability of Syer and Tremaine’s madeto-measure method and Schwarzschild’s method for stellar dynamical modeling to do so for edge-on oblate axisymmetric galaxies.Overall,we find that the methods do not accurately recover the 3D distributions,with the made-to-measure method producing more accurate estimates than Schwarzschild’s method.Our results have implications broader than just luminosity density,and affect other luminosity-weighted distributions within galaxies,for example,age and metallicity.

A Possible γ-Ray Pulsation from PSR J1740-5340B in the Globular Cluster NGC 6397

Recently, a new radio millisecond pulsar(MSP) J1740-5340B, hosted in the globular cluster(GC) NGC 6397,was reported with a 5.78 ms spin period in an eclipsing binary system with a 1.97 days orbital period. Based on a modified radio ephemeris updated by tool tempo2, we analyze the ~15 yr γ-ray data obtained from the Large Area Telescope on board the Fermi Gamma-ray Space Telescope and detect PSR J1740-5340B's γ-ray pulsation at a confidence level of ~4σ with a weighted H-test value of ~26. By performing a phase-resolved analysis, the γ-ray luminosity in on-pulse interval of PSR J1740-5340B is L_(γ)~ 3.8 × 10^(33) erg s^(-1) using NGC 6397's distance of 2.48 kpc. And γ-rays from the on-pulse part of PSR J1740-5340B contribute ~90% of the total observed γ-ray emissions from NGC 6397. No significant γ-ray pulsation of another MSP J1740-5340A in the GC is detected.Considering that the previous four cases of MSPs in GCs, more data in γ-ray, X-ray, and radio are encouraged to finally confirm the γ-ray emissions from MSP J1740-5340B, especially starving for a precise ephemeris.

The pc-scale radio structure of MIR-observed radio galaxies

We investigated the relationship between the accretion process and jet properties by utilizing very long baseline array （VLBA） and mid-infrared （MIR） data for a sample of 45 3CRR radio galaxies selected with a flux density at 178MHz 〉 16.4Jy, 5 GHz very large array （VLA） core flux density ≥7 mJy and MIR observations. The pc-scale radio structure at 5 GHz is presented by using our VLBA observations for 21 sources acquired in February, 2016, the analysis of archival data for 16 objects and directly obtaining measurements for eight radio galaxies available from literatures. The accretion mode is constrained from the Eddington ratio with a dividing value of 0.01, which is estimated from the MIR-based bolometric luminosity and the black hole masses. While most Fanaroff-Riley type II radio galaxies （FRIIs） have higher Eddington ratio than Fanaroff-Riley type I radio galaxies （FRIs）, we found that there is indeed no single correspondence between the FR morphology and accretion mode with eight FRIIs at low accretion rate and two FRIs at high accretion rate. There is a significant correlation between the VLBA core luminosity at 5 GHz and the Eddington ratio. Various morphologies are identi- fied in our sample, including core only, single-sided core-jet and two-sided core-jet structures. We found that the higher accretion rate may be more likely related with the core-jet structure, thus generating a more extended jet. These results imply that the higher accretion rates are likely able to produce more powerful jets. There is a strong correlation between the MIR luminosity at 15 ktm and VLBA 5 GHz core luminosity, in favor of the tight relation between the accretion disk and jets. In our sample, the core brightness temperature ranges from 109 to 101338 K with a median value of 10^11.09K, indicating that systematically the beaming effect may not be significant. The exceptional cases, FRIs at high accretion rates and FRIIs at low accretion rates, are exclusively at the high and low ends, respectively, of the distribution of the flux ratio for VLBA core to 178 MHz flux density. It is not impossible that the locations of these sources are due to the recent shining or weakening of their central engines （i.e., both accretion and jet）.

Study of Complex Nitrogen and Oxygen-bearing Molecules toward the High-mass Protostar IRAS 18089–1732

The observation of oxygen(O)-and nitrogen(N)-bearing molecules gives an idea about the complex prebiotic chemistry in the interstellar medium.Recent millimeter and submillimeter wavelength observations have shown the presence of complex O-and N-bearing molecules in the star formation regions.So,the investigation of those molecules is crucial to understanding the chemical complexity in the star-forming regions.In this article,we present the identification of the rotational emission lines of N-bearing molecules ethyl cyanide(C_(2)H_(5)CN)and cyanoacetylene(HC_(3)N),and O-bearing molecule methyl formate(CH_(3)OCHO)toward high-mass protostar IRAS18089–1732 using the Atacama Compact Array.We also detected the emission lines of both the N-and O-bearing molecule formamide(NH_(2)CHO)in the envelope of IRAS 18089–1732.We have detected the v=0 and 1 state rotational emission lines of CH_(3)OCHO.We also detected the two vibrationally excited states of HC_(3)N(v7=1 and v7=2).The estimated fractional abundances of C_(2)H_(5)CN,HC_(3)N(v7=1),HC_(3)N(v7=2),and NH_(2)CHO toward IRAS 18089–1732 are(1.40±0.5)×10^(-10),(7.5±0.7)×10^(-11),(3.1±0.4)×10^(-11),and(6.25±0.82)×10^(-11)respectively.Similarly,the estimated fractional abundances of CH_(3)OCHO(v=0)and CH_(3)OCHO(v=1)are(1.90±0.9)×10^(-9)and(8.90±0.8)×10^(-10),respectively.We also created the integrated emission maps of the detected molecules,and the observed molecules may have originated from the extended envelope of the protostar.We show that C_(2)H_(5)CNand HC_(3)N are most probably formed via the subsequential hydrogenation of the CH_(2)CHCNand the reaction between C_(2)H_(2)and CN on the grain surface of IRAS 18089–1732.We found that NH_(2)CHO is probably produced due to the reaction between NH_(2)and H_(2)CO in the gas phase.Similarly,CH_(3)OCHO is possibly created via the reaction between radical CH_(3)O and radical HCO on the grain surface of IRAS 18089–1732.

To the Theory of Galaxies Rotation and the Hubble Expansion in the Frame of Non-Local Physics

The unified generalized non-local theory is applied for mathematical modeling of cosmic objects. For the case of galaxies the theory leads to the flat rotation curves known from observations. The transformation of Kepler’s regime into the flat rotation curves for different solitons is shown. The Hubble expansion with acceleration is explained as result of mathematical modeling based on the principles of non-local physics. Peculiar features of the rotational speeds of galaxies and effects of the Hubble expansion need not in the introduction of new essence like dark matter and dark energy. The origin of difficulties consists in the total Oversimplification following from the principles of local physics.

Model-fitting of the kinematics of superluminal components in blazar 3C 279

A precessing jet-nozzle model with a precession period of about 25 yr has been proposed by Qian to interpret the change with time of the ejection position an- gle of the superluminal components observed using very long baseline interferometry （VLBI） in the blazar 3C 279. We discuss the kinematic properties of six superluminal knots （C3, C4, C7a, C8, C9 and C10） and show that their trajectory, core-distance and apparent speed, derived from VLBI observations, can be consistently well fitted by the model. Their intrinsic Lorentz factors of bulk superluminal motion are thus derived, and the evidence shows no relation between Lorentz factor and the precession phase. Interestingly, for the C7a and C8 knots, the fitted core-distance ranges from ,,～0.1 mas to ～0.4 mas and for knots C9 and C10 from ～0.2mas to ～1.0-1.5 mas. For knot C4, its trajectory and apparent velocity are well fitted in the core-distance range from H1 mas to ～5 mas, taking into account a curvature of the trajectory at core-distance larger than ,,～3 mas. The consistent fitting of the kinematics of these components clearly demonstrates that the amplitude function and collimation param- eter adopted in the precession model are appropriate and applicable for both the in- ner and outer parts of the jet in 3C 279, but in some cases the jet curvature in the outer parts （or deviation from the model trajectory） needs to be seriously taken into consideration. With the exception of C4, the ejection position angles derived from the precession model are consistent with the values measured by VLBI observations （within about 3° - 6°）. Undoubtedly, the consistent interpretation of the kinematics in terms of the precession model for these superluminal components, with their ejection time spanning -～24 yr, significantly expands its applicability and implies that regular patterns of trajectories （or rotating channels） could exist in some periods.

Star-Forming Galaxies at z～2 in the Hubble Ultra Deep Field

Using a simple color selection based on B-, z- and K-band photometry, BzK =（z - K）AB - （B - Z）AB 〉 -0.2, we picked out 52 star-forming galaxies at 1.4 ≤z ≤ 2.5 （sBzKs） from a K-band selected sample （Kvega 〈 22.0） in an area of - 5.5 arcmin^2 of the Hubble Ultra Deep Field （UDF）. We develop a new photometric redshift method, and the error in our photometric redshifts is less than 0.02（1 ＋ z）. From the photometric redshift distribution, we find the BzK color criterion can be used to select star-forming galaxies at 1.4≤ z ≤ 2.5 with Kvega 〈 22.0. Down to Kvega 〈 22.0, the number counts of sBzKs increase linearly with the K magnitude; the sBzKs are strongly clustered, and most of them have irregular morphologies on the ACS images. They have a median reddening of E（B - V） - 0.28, an average star formation rate of - 36 M⊙ yr^-1 and a typical stellar mass of - 10^10 M⊙. The UV criterion for the galaxies at z - 2 can select most of the faint sBzKs in the UDF, but it does not work well for bright, massive, highly-reddened, actively star-forming galaxies.

Do Radio-loud Active Galactic Nuclei really follow the same M_(BH)-σ_* Relation as Normal Galaxies?

In an examination of the relationship between the black hole mass MBH and stellar velocity dispersion σ＊ in radio-loud active galactic nuclei （AGNs）, we studied two effects which may cause uncertainties in the black hole mass estimates of radio-loud AGNs： the relativistic beaming effect on the observed optical continuum radiation and the orientation effect on the broad emission line width. After correcting these two effects, we re-examined the MBH- σ[OIII] relation for a sample of radio-loud and radio-quiet AGNs, and found the relation for radio-loud AGNs still deviated from that for nearby normal galaxies and radio-quiet AGNs. We also found there is no significant correlation between radio jet power and narrow [OIII] line width, indicating absence of strong interaction between radio jet and narrow line region. It may be that the deviation of the MBH-σ＊ relation of radio-loud AGNs is intrinsic, or that the [OIII] line width is not a good indicator of σ＊ for radio-loud AGNs.

Peculiar early-type galaxies with central star formation

Early-type galaxies （ETGs） are very important for understanding the formation and evolution of galaxies. Recent observations suggest that ETGs are not simply old stellar spheroids as we previously thought. Widespread recent star formation, cool gas and dust have been detected in a substantial fraction of ETGs. We make use of the radial profiles of 9 - r color and the concentration index from the Sloan Digital Sky Survey database to pick out 31 peculiar ETGs with central blue cores. By analyzing the photometric and spectroscopic data, we suggest that the blue cores are caused by star formation activities rather than the central weak active galactic nucleus. From the results of stellar population synthesis, we find that the stellar population of the blue cores is relatively young, spreading from several Myr to less than one Gyr. In 14 galaxies with H I observations, we find that the average gas fraction of these galaxies is about 0.55. The bluer galaxies show a higher gas fraction, and the total star forma- tion rate （SFR） correlates very well with the H I gas mass. The star formation history of these ETGs is affected by the environment, e.g. in the denser environment the H I gas is less and the total SFR is lower. We also discuss the origin of the central star formation of these early-type galaxies.

Structural Properties of Early-Type Galaxies from the SDSS DR2

Two-dimensional bulge/disk light decomposition with GIM2D in both the r- and g-bands has been applied to a sample of 129 early-type galaxies brighter than 13.5 magnitude in the r-band, selected from the Sloan Digital Sky Survey Data Release 2. Intensity-weighted Fourier coefficient （α4/α） was also derived for each sample galaxy. Our analysis shows that there are correlations between bulge-to-total light ratio （B/T） with bulge Sersic index nB and between bulge and disk scale sizes. Isophotal shape parameter （α4/α） is not correlated with BIT and riB. Both bulge and disk components satisfy a color-magnitude relation. The space Fundamental Plane analysis shows that galaxies with larger B/T tend to lie tighter and closer to the line of k1 ＋ k2 = 8 （the so-called ＂zone of avoidance＂） than the galaxies with smaller B/T. It indicates that existence of the disk component may lead to scatter of the distribution on the Fundamental Plane. Our analysis also shows that k1 ＋ k2 correlates with （g-r） color and B/T, but does not correlate with （α4/α） for early-type galaxies. The fitted parameters and other retrieved parameters used in this paper for all sample galaxies are available online.

Inner jet kinematics and the viewing angle towards the γ-ray narrow-line Seyfert 1 galaxy 1H 0323＋342

Near-Eddington accretion rates onto low-mass black holes are thought to be a prime driver of the multi-wavelength properties of the narrow-line Seyfert 1 （NLS1） population of active galactic nuclei （AGNs）. Orientation effects have repeatedly been considered as another important factor involved, but detailed studies have been hampered by the lack of measured viewing angles towards this type of AGN. Here we present multi-epoch, 15 GHz VLBA images （MOJAVE program） of the radio-loud and Fermi/LAT- detected NLS 1 galaxy 1H 0323＋342. These are combined with single-dish, multi-frequency radio monitoring of the source＇s variability, obtained with the Effelsberg 100-m and IRAM 30-m telescopes, in the course of the F-GAMMA program. The VLBA images reveal six components with apparent speeds of 1 - 7 c, and one quasi-stationary feature. Combining the obtained apparent jet speed （βapp） and variability Doppler factor （Dvar） estimates together with other methods, we constrain the viewing angle 0 towards 1H 0323＋342 to 0 ≤ 4°-13°. Using literature values of βapp and Dvar, we also deduce a viewing angle of 〈8°-9° towards another radio- and γ-ray-loud NLS1, namely SBS 0846＋513.