STUDY OF MILLI-JANSKY SEYFERT GALAXIES WITH STRONG FORBIDDEN HIGH-IONIZATION LINES USING THE VERY LARGE ARRAY SURVEY IMAGES

Dharam V. Lal 한국천문학회 2015 Journal of The Korean Astronomical Society Vol.48 No.6

We study the radio properties at 1.4 GHz of Seyfert galaxies with strong forbidden highionization lines (FHILs), selected from the Sloan Digital Sky Survey – a large-sized sample containing nearly equal proportion of diverse range of Seyfert galaxies showing similar redshift distributions compiled by Gelbord et al. (2009) using the Very Large Array survey images. The radio detection rate is low, 49%, which is lower than the detection rate of several other known Seyfert galaxy samples. These galaxies show low star formation rates and the radio emission is dominated by the active nucleus with ≤10% contribution from thermal emission, and possibly, none show evidence for relativistic beaming. The radio detection rate, distributions of radio power, and correlations between radio power and line luminosities or X-ray luminosity for narrow-line Seyfert 1 (NLS1), Seyfert 1 and Seyfert 2 galaxies are consistent with the predictions of the unified scheme hypothesis. Using correlation between radio and [O III] 5007°A luminosities, we show that ∼8% sample sources are radio-intermediate and the remaining are radio-quiet. There is possibly an ionization stratification associated with clouds on scales of 0.1–1.0 kpc, which have large optical depths at 1.4GHz, and it seems these clouds are responsible for free–free absorption of radio emission from the core; hence, leading to low radio detection rate for these FHIL-emitting Seyfert galaxies.

Testing the Consistency of Unified Scheme of Seyfert Galaxies

Evaristus U. I,Innocent O. Eya,Christian I. Eze 한국우주과학회 2022 Journal of Astronomy and Space Sciences Vol.39 No.2

The unified scheme of Seyfert galaxies hypothesizes that the observed differences between the two categories of Seyfert galaxies, type 1 (Sy1) and type 2 (Sy2) are merely due to the difference in the orientation of the toroidal shape of the obscuring material in the active galactic nuclei. We used in this paper, a sample consisting of 120 Seyfert galaxies at 1.40 × 109 Hz in radio, 2.52 × 1017 Hz in X-ray and 2.52 × 1023 Hz in γ-ray luminosities observed by the Fermi Large Area Telescope (Fermi- LAT) in order to test the unified scheme of radio-quiet Seyfert galaxies. Our main results are as follows: (i) We found that the distributions of multiwave luminosities (Lradio, LX-ray, and Lγ-ray) of Sy1 and Sy2 are completely overlapped with up to a factor of 4. The principal component analysis result reveals that Sy1 and Sy2 also occupy the same parameter spaces, which agrees with the notion that Sy1 and Sy2 are the same class objects. A Kolmogorov-Smirnov test performed on the sub-samples indicates that the null hypothesis (both are from the same population) cannot be rejected with chance probability p ~ 0 and separation distance K = 0.013. This result supports the fact that there is no statistical difference between the properties of Sy1 and Sy2 (ii) We found that the coefficient of the best-fit linear regression equation between the common properties of Sy1 and Sy2 is significant (r > 0.50) which plausibly implies that Sy1 and Sy2 are the same type of objects observed at different viewing angle.

Relation between Black Hole Mass and Bulge Luminosity in Hard X-ray Selected Type 1 AGNs

손수연,김민진,Aaron J. Barth,Luis C. Ho 한국천문학회 2022 Journal of The Korean Astronomical Society Vol.55 No.2

Using I-band images of 35 nearby (z < 0.1) type 1 active galactic nuclei (AGNs) obtained with Hubble Space Telescope, selected from the 70-month Swift-BAT X-ray source catalog, we investigate the photometric properties of the host galaxies. With a careful treatment of the point-spread function (PSF) model and imaging decomposition, we robustly measure the I-band brightness and the effective radius of bulges in our sample. Along with black hole (BH) mass estimates from single-epoch spectroscopic data, we present the relation between BH mass and I-band bulge luminosity (M_{BH}--M_{I, bul} relation) of our sample AGNs. We find that our sample lies offset from the M_{BH}--M_{I, bul} relation of inactive galaxies by 0.4 dex, i.e., at a given bulge luminosity, the BH mass of our sample is systematically smaller than that of inactive galaxies. We also demonstrate that the zero point offset in the M_{BH}--M_{I, bul} relation with respect to inactive galaxies is correlated with the Eddington ratio. Based on the Kormendy relation, we find that the mean surface brightness of ellipticals and classical bulges in our sample is comparable to that of normal galaxies, revealing that bulge brightness is not enhanced in our sample. As a result, we conclude that the deviation in the M_{BH}--M_{I, bul} relation from inactive galaxies is possibly because the scaling factor in the virial BH mass estimator depends on the Eddington ratio. Using I-band images of 35 nearby (z < 0.1) type 1 active galactic nuclei (AGNs) obtained with Hubble Space Telescope, selected from the 70-month Swift-BAT X-ray source catalog, we investigate the photometric properties of the host galaxies. With a careful treatment of the point-spread function (PSF) model and imaging decomposition, we robustly measure the I-band brightness and the effective radius of bulges in our sample. Along with black hole (BH) mass estimates from single-epoch spectroscopic data, we present the relation between BH mass and I-band bulge luminosity (M_{BH}–M_{I,bul} relation) of our sample AGNs. We find that our sample lies offset from the M_{BH}–M_{I,bul} relation of inactive galaxies by 0.4 dex, i.e., at a given bulge luminosity, the BH mass of our sample is systematically smaller than that of inactive galaxies. We also demonstrate that the zero point offset in the M_{BH}–M_{I,bul} relation with respect to inactive galaxies is correlated with the Eddington ratio. Based on the Kormendy relation, we find that the mean surface brightness of ellipticals and classical bulges in our sample is comparable to that of normal galaxies, revealing that bulge brightness is not enhanced in our sample. As a result, we conclude that the deviation in the M_{BH}–M_{I,bul} relation from inactive galaxies is possibly because the scaling factor in the virial BH mass estimator depends on the Eddington ratio.

DETECTION OF X-RAY EMISSION FROM GALAXIES INSIDE AND TOWARDS THE NEARBY VOIDS

KIM CHULHEE,BOLLER TH.,GHOSH KAJAL K. The Korean Astronomical Society 2005 Journal of The Korean Astronomical Society Vol.38 No.1

We searched for X-ray emission from the 665 galaxies inside and towards the nearby voids by analyzing the ROSAT All-Sky Survey (RASS) data as well as the ROSAT pointed observations (PSPC). As a result we have detected six X-ray emitting galaxies. Two (UGC 10205 and NGC 7509) are in the high density region in the local void, three (UGC 749, MCG +11-10-073, and Mrk 464) are towards the nearby voids, and UGC 32 is located in the low density region. We carried out a timing analysis for both Mrk 464 and UGC 32, and a spectral analysis for Mrk 464. The light curve of Mrk 464 shows the possibility of periodic X-ray flux variation and UGC 32 shows weak, but rapid variation.

THE GALAXY-BLACK HOLE CONNECTION IN THE LOCAL UNIVERSE

Schawinski, Kevin,Fellow, Einstein The Korean Astronomical Society 2010 天文學論叢 Vol.25 No.3

Recent results from large surveys of the local universe show that the galaxy-black hole connection is linked to host morphology at a fundamental level and that there are two fundamentally different modes of black hole growth. The fraction of early-type galaxies with actively growing black holes, and therefore the AGN duty cycle, declines significantly with increasing black hole mass. Late-type galaxies exhibit the opposite trend: the fraction of actively growing black holes increases with black hole mass. Issues of AGN selection bias and prospects for near-future efforts with high redshift data are discussed.

Does the Jet Production Efficiency of Radio Galaxies Control Their Optical AGN Types?

Sascha Trippe 한국천문학회 2014 Journal of The Korean Astronomical Society Vol.47 No.4

The jet production efficiency of radio galaxies can be quantified by comparison of their kinetic jet powers Pjet and Bondi accretion powers PB. These two parameters are known to be related linearly, with the jet power resulting from the Bondi power by multiplication with an efficiency factor of order 1%. Using a recently published (Nemmen & Tchekhovskoy 2014 high-quality sample of 27 radio galaxies, I construct a PB-Pjet diagram that includes information on optical AGN types as far as available. This diagram indicates that the jet production efficiency is a function of AGN type: Seyfert 2 galaxies seem to be systematically (with a false alarm probability of 4.3×10-4 less efficient, by about one order of magnitude, in powering jets than Seyfert 1 galaxies, LINERs, or the remaining radio galaxies. This suggests an evolutionary sequence from Sy2s to Sy,1s and LINERs, controlled by an interplay of jets on the one hand and dust and gas in galactic nuclei on the other hand. When taking this effect into account, the PB-Pjet relation is probably much tighter intrinsically than currently assumed.

OPTICAL AND NEAR-INFRARED IMAGING OF THE IRAS 1-JY SAMPLE OF ULTRALUMINOUS INFRARED GALAXIES

KIM D.-C. The Korean Astronomical Society 2003 Journal of The Korean Astronomical Society Vol.36 No.3

Optical (R) and near-infrared (K') images of the IRAS 1-Jy sample of 118 ultraluminous infrared galaxies have been studied. All but one object in the 1-Jy sample show signs of strong tidal interaction/merger. Most of them harbor a single disturbed nucleus and are therefore in the later stages of a merger event. Single-nucleus ULIGs show a broad distribution in host magnitudes with significant overlap with those of quasars. The same statement applies to R - K' colors in ULIG and quasar hosts. An analysis of the surface brightness profiles of the host galaxies in single-nucleus sources reveals that about $35\%$ of the Rand K' surface brightness profiles are well fit by an elliptical-like $R^{1/4}$-law, while only $2\%$ are well fit by an exponential disk. Another $38\%$ of the single-nucleus systems are fit equally well with an exponential or de Vaucouleurs profile. Elliptical-like hosts are most common among merger remnants with Seyfert 1 nuclei ($83\%$) and Seyfert 2 optical characteristics ($69\%$). The mean effective radius of these ULIGs is 4.80 $\pm$ 1.37 kpc at Rand 3.48 $\pm$ 1.39 kpc at K'. These values are in excellent agreement with recent quasar measurements obtained at H with HST. The hosts of elliptical-like 1-Jy systems follow with some scatter the same ${\mu}e - r_e$ relation, giving credence to the idea that some of these objects may eventually become elliptical galaxies if they get rid of their excess gas or transform this gas into stars.

The kinematics of the Seyfert 2 galaxy NGC 5728 circumnuclear region

Son, D.-H.,Hyung, S.,Ferruit, P.,Pé,contal, E.,Lee, W.-B. Blackwell Publishing Ltd 2009 MONTHLY NOTICES- ROYAL ASTRONOMICAL SOCIETY Vol.395 No.2

<P>ABSTRACT</P><P>We secured spectral images of the circumnuclear, 12 × 10 arcsec<SUP>2</SUP> region of the Seyfert 2 galaxy NGC 5728 with the Optically Adaptive System for Imaging Spectroscopy at the Canada–France–Hawaii Telescope 3.6-m telescope. The radial velocity distribution of the two bright zones, main central (C) core and north-west (NW) core, and strategically important points along the position angles, PA 33°, 90°, 123° and 143°, are analysed. The large-scale reconstructed monochromatic images of the Hα, Hβ, [O <SMALL>III</SMALL>] and [N <SMALL>II</SMALL>] lines show a bipolar morphology along PA ∼ 123°. The prominent elliptical ring is seen in the Hα and Hβ monochromatic images. Our analysis implies that this ring is rotating in the same clockwise direction as that of the galactic disc; this elliptical ring is in fact a projected result of a circular ring of radius ∼5.4 arcsec, with <I>i</I>∼ 50° (nearly aligned with the host galactic plane).</P><P>We used the [O <SMALL>III</SMALL>]5007 line profiles for a detailed analysis of kinematics in the circumnuclear region of the NGC 5728. The [O <SMALL>III</SMALL>]5007 line profiles reveal distinct kinematical structures. (1) The strongest component of Doppler peaks: two core components, consisting of the receding main C-core and the approaching NW-core with the radial velocities, <I>V</I><SUB>r</SUB>≃+250 and −240 (or −250) km s<SUP>−1</SUP>, respectively. These two cores consist of a roughly spherically symmetric distribution of the gas with radii of <I>r</I>∼ 1.0 arcsec (at <I>V</I><SUB>r</SUB>≃+240 km s<SUP>−1</SUP>) and 0.9 arcsec (at <I>V</I><SUB>r</SUB>≃−240 km s<SUP>−1</SUP>), respectively. Hints of the presence of inflows around these cores are observed. (2) The next strong line profile component: this component corresponds to the bipolar cone aligned PA ∼ 123°. (3) The reverse S-shaped kinematical boundary which runs through the double-peaked zone of 6–7 arcsec long in the galactic major axis direction is likely to be caused by a combination of the disc rotation of the host galaxy and the revolution of the two central cores.</P>

X-RAY ARCHIVAL DATA ANALYSIS OF TIME VARIABILITIES IN SEYFERT GALAXY MCG-2-58-22

CHOI CHUL-SUNG,DOTANI TADAYASU,YI INSU,FLETCHER ANDRE,KIM CHULHEE The Korean Astronomical Society 2001 Journal of The Korean Astronomical Society Vol.34 No.3

We report results from an analysis of the X-ray archival data on MCG-2-58-22 obtained with Ginga, ROSAT and ASCA. By analyzing both short- and long-term light curves, we find clear time variations, ranging widely from, $\~10^3$ s to more than several years, in the X-ray energy range 0.1 - 10 keV. In addition, a flare is detected in 1991, overlaid on a gradual, secular flux decrease from 1979 to 1993; this flare has a time scale of about 1 year, and the X-ray flux increased by at least a factor of 3. The implications of these observational results are discussed in terms of accretion flow dynamics near a supermassive black hole.

AKARI IRC INFRARED 2.5-5 ㎛ SPECTROSCOPY OF NEARBY LUMINOUS INFRARED GALAXIES

Imanishi, Masatoshi,Nakagawa, Takao,Shirahata, Mai,Ohyama, Yoichi,Onaka, Takashi The Korean Astronomical Society 2012 天文學論叢 Vol.27 No.4

We present the result of systematic AKARI IRC infrared $2.5-5{\mu}m$ spectroscopy of >100 nearby luminous infrared galaxies, to investigate the energetic roles of starbursts and optically-elusive buried AGNs. Based on (1) the equivalent widths of the $3.3{\mu}m$ PAH emission features, (2) the optical depths of absorption features, and (3) continuum slopes, we can disentangle emission from starbursts and AGNs. We find that the energetic importance of buried AGNs increases with increasing galaxy infrared luminosities, suggesting that the AGN-starburst connections (and thereby possible AGN feedback to host galaxies) are luminosity dependent.