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 dispersionσ* 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 ofσ* for radio-loud AGNs.

Comparison of some properties of star forming galaxies and active galactic nuclei between two BOSS galaxy samples from SDSS DR9

Using the LOWZ and CMASS samples of the ninth data release(DR9)from the SDSS-III Baryon Oscillation Spectroscopic Survey(BOSS), I investigate properties of star forming galaxies and active galactic nuclei(AGNs). The CMASS sample seriously suffers from the radial selection effect, even within the redshift0.44 ≤ z ≤ 0.6, which will likely lead to statistical conclusions in the CMASS sample being less robust. In the LOWZ sample, the fraction of star-forming galaxies is nearly constant from the least dense regime to the densest regime; the AGN fraction is also insensitive to the local environment. In addition, I note that in the LOWZ sample, the distributions of stellar mass and stellar velocity dispersion for star forming galaxies and AGNs are nearly the same.

A study of active galactic nuclei in low surface brightness galaxies with Sloan Digital Sky Survey spectroscopy

Active galactic nuclei (AGNs) in low surface brightness galaxies (LSBGs) have received little attention in previous studies. We present a detailed spectral analysis of 194 LSBGs from the Impey et al. (1996) APM LSBG sample which has been observed spec- troscopically by the Sloan Digital Sky Survey Data Release 5 (SDSS DR5). Our elaborate spectral analysis enables us to carry out, for the first time, reliable spectral classification of nuclear processes in LSBGs based on the standard emission line diagnostic diagrams in a rigorous way. Star-forming galaxies are common, as found in about 52% of LSBGs. We find that, contrary to some previous claims, the fraction of galaxies that contain AGNs is significantly lower than that found in nearby normal galaxies of high surface brightness. This is qualitatively in line with the finding of Impey et al. This result holds true even within each morphological type from Sa to Sc. LSBGs that have larger central stellar ve- locity dispersions or larger physical sizes tend to have a higher chance of harboring an AGN. For three AGNs with broad emission lines, the black hole masses estimated from the emission lines are broadly consistent with the well known M-σ? relation established for normal galaxies and AGNs.

Feedback of Active Galactic Nuclei in Seyfert 2 Galaxies

It is well accepted that feedback from active galactic nuclei(AGNs) plays an important role in the coevolution of the supermassive black hole(SMBH) and its host galaxy,but the concrete mechanism of feedback remains unclear.A considerable body of evidence suggests that AGN feedback suppresses star formation in the host galaxy.We assemble a sample of Seyfert 2 galaxies with recent observational data of compact nuclear starbursts and estimate the gas surface density as a function of column density to illuminate the relation between feedback and AGN properties.Although there are some uncertainties,our data still imply the deviation from the star formation law(Kennicutt-Schmidt law).Further,they indicate that:(1) Feedback correlates with the Eddington ratio,rather than with the mass of SMBH,as a result of decreasing star formation efficiency.(2) The SMBH and the torus are probably undergoing coevolution.Conclusions presented here can be refined through future high resolution CO or HCN observations.

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(NLS1s, PMN J0948+0022 and 1H0323+342) in different flux stages with one-zone leptonic models, we find a universal correlation between their Doppler factors(δ) and peak luminosities(L_c) of external Compton scattering bumps. Compiling a combined sample of FSRQs and GeV NLS1s, it is found that both FSRQs and GeV NLS1s in different stages and in different sources follow the same δ-L_c correlation well. This indicates that the variations of observed luminosities may be essentially due to the Doppler boosting effect. The universal δ-L_c relation between FSRQs and GeV NLS1s 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 L_c with the observed luminosity in the Fermi/LAT band(L_(LAT)), this correlation holds and it may serve as an empirical indicator of δ. We estimate the δ values with L_(LAT) 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.

The AGN Feedback in Compact Galaxies:On the Impact of a More Massive Central Black Hole

We conduct high-resolution hydrodynamical simulations using the MACER framework to investigate the interplay between the interstellar medium,active galactic nuclei(AGN)feedback and black hole(BH)feeding in a massive compact galaxy,with an emphasis on the impact of different central BH masses.We find that with a more massive central BH,high-speed outflows are more prominent,and the gas fraction in the compact galaxy is reduced.Due to the lower gas density and higher gas temperature,the compact galaxy with a more massive BH(MAS galaxy)remains predominantly single-phase with the cooling time t_(cool)■100t_(ff).In contrast,the compact galaxy with the reference BH mass(REF galaxy)maintains a higher gas fraction with a shorter cooling time,slightly more multiphase gas and less prominent outflows.We further demonstrate that the difference in gas thermal states and kinematics is caused by the stronger AGN feedback in the compact galaxy with a more massive BH,where the AGN wind power is twice as much as that with the reference BH.Since the AGN feedback efficiently suppresses the inflow rate and the BH feeding rate,the BH mass growth is significant in neither the compact galaxy with the reference BH nor that with the more massive BH,only by 24%and 11%of the initial BH mass,respectively,over the entire evolution time of 10 Gyr.We thus posit that without ex situ mass supply from mergers,the massive BHs in compact galaxies cannot grow significantly via gas accretion during the late phase,but might have already formed by the end of the rapid early phase of galaxy formation.

A Pair of New Spirocyclic Alkaloid Enantiomers with TrxR Inhibitory Activities Were Isolated from Marine-Derived Aspergillus ruber TX-M4-1

One new spirocyclic alkaloid,5-isopentenyl-cryptoechinuline D(1),along with 11 known compounds(2–12),were iso-lated from a marine fungus Aspergillus ruber TX-M4-1.The structures of compounds 1–12 were elucidated by spectroscopic evi-dences.Compound 1 was initially isolated as an enantiomer,and further separation of 1 by chiral HPLC afforded a pair of enantio-mers,including(-)-5-isopentenyl-cryptoechinuline D(1a)and(+)-5-isopentenyl-cryptoechinuline D(1b).Their absolute configura-tions were elucidated by ECD spectroscopic data.Compounds 1a,5 and 10 could inhibit thioredoxin reductase(TrxR)activity with IC50 values of 6.2,36.3 and 18.6μmol L^(-1),respectively.Surface plasmon resonance(SPR)study also demonsrated the interactions between compounds 6,8 and Niemann-Pick C1 Like 1(NPC1L1)respectively,which indicate that compounds 6 and 8 are potential NPC1L1 inhibitors.

18β-glycyrrhetinic acid promotes gastric cancer cell autophagy and inhibits proliferation by regulating miR-328-3p/signal transducer and activator of transcription 3

BACKGROUND Gastric cancer(GC)is one of the most common cancer types worldwide,and its prevention and treatment methods have garnered much attention.As the active ingredient of licorice,18β-glycyrrhetinic acid(18β-GRA)has a variety of pharmacological effects.The aim of this study was to explore the effective target of 18β-GRA in the treatment of GC,in order to provide effective ideas for the clinical prevention and treatment of GC.AIM To investigate the mechanism of 18β-GRA in inhibiting cell proliferation and promoting autophagy flux in GC cells.METHODS Whole transcriptomic analyses were used to analyze and screen differentially expressed microRNAs(miRNAs)in GC cells after 18β-GRA intervention.Lentivirus-transfected GC cells and the Cell Counting Kit-8 were used to detect cell proliferation ability,cell colony formation ability was detected by the clone formation assay,and flow cytometry was used to detect the cell cycle and apoptosis.A nude mouse transplantation tumor model of GC cells was constructed to verify the effect of miR-328-3p overexpression on the tumorigenicity of GC cells.Tumor tissue morphology was observed by hematoxylin and eosin staining,and microtubule-associated protein light chain 3(LC3)expression was detected by immunohistochemistry.TransmiR,STRING,and miRWalk databases were used to predict the relationship between miR-328-3p and signal transducer and activator of transcription 3(STAT3)-related information.Expression of STAT3 mRNA and miR-328-3p was detected by quantitative polymerase chain reaction(qPCR)and the expression levels of STAT3,phosphorylated STAT3(p-STAT3),and LC3 were detected by western blot analysis.The targeted relationship between miR-328-3p and STAT3 was detected using the dual-luciferase reporter gene system.AGS cells were infected with monomeric red fluorescent protein-green fluorescent protein-LC3 adenovirus double label.LC3 was labeled and autophagy flow was observed under a confocal laser microscope.RESULTS The expression of miR-328-3p was significantly upregulated after 18β-GRA intervention in AGS cells(P=4.51E-06).Overexpression of miR-328-3p inhibited GC cell proliferation and colony formation ability,arrested the cell cycle in the G0/G1 phase,promoted cell apoptosis,and inhibited the growth of subcutaneous tumors in BALB/c nude mice(P<0.01).No obvious necrosis was observed in the tumor tissue in the negative control group(no drug intervention or lentivirus transfection)and vector group(the blank vector for lentivirus transfection),and more cells were loose and necrotic in the miR-328-3p group.Bioinformatics tools predicted that miR-328-3p has a targeting relationship with STAT3,and STAT3 was closely related to autophagy markers such as p62.After overexpressing miR-328-3p,the expression level of STAT3 mRNA was significantly decreased(P<0.01)and p-STAT3 was downregulated(P<0.05).The dual-luciferase reporter gene assay showed that the luciferase activity of miR-328-3p and STAT33’untranslated regions of the wild-type reporter vector group was significantly decreased(P<0.001).Overexpressed miR-328-3p combined with bafilomycin A1(Baf A1)was used to detect the expression of LC3 II.Compared with the vector group,the expression level of LC3 II in the overexpressed miR-328-3p group was downregulated(P<0.05),and compared with the Baf A1 group,the expression level of LC3 II in the overexpressed miR-328-3p+Baf A1 group was upregulated(P<0.01).The expression of LC3 II was detected after intervention of 18β-GRA in GC cells,and the results were consistent with the results of miR-328-3p overexpression(P<0.05).Additional studies showed that 18β-GRA promoted autophagy flow by promoting autophagosome synthesis(P<0.001).qPCR showed that the expression of STAT3 mRNA was downregulated after drug intervention(P<0.05).Western blot analysis showed that the expression levels of STAT3 and p-STAT3 were significantly downregulated after drug intervention(P<0.05).CONCLUSION 18β-GRA promotes the synthesis of autophagosomes and inhibits GC cell proliferation by regulating the miR-328-3p/STAT3 signaling pathway.

Synthesis and Antitumor Activity of 3-[2-(4-Hydroxy-Phenyl)-Ethyl]-Benzo[d] Isoxazole-4,6-Diol

A new phloretin derivative 1 3-[2-(4-hydroxy-phenyl)-ethyl]-benzo[d] isoxazole-4,6-diol (yield 63%) was synthesized from phloretin by carbonyl nucleophilic addition condensation reaction. Its structure was characterized by 1H NMR, 13C NMR and HR-MS. The phloretin, compound 1, resveratrol and acetylated resveratrol were determined by comparing them with paclitaxel. Anti-tumor activity of alcohol on SPC-A1, EC109, A549, MCF-7 and MDA-MB-231 cell lines. Compound 1 showed better antitumor activity than docetaxel against A549 tumor cells.

Fixed-Bed Column Adsorption Modeling of MnO4- Ions from Acidic Aqueous Solutions on Activated Carbons Prepared with the Biomass

Activated carbons calcined at 400˚C and 600˚C (AC-400 and AC-600), prepared using palm nuts, collected in the town of Franceville in Gabon, were used to study the dynamic adsorption of MnO4- ions in acidic media on fixed bed column and on the kinetic modeling of experimental data of breakthrough curves of MnO4- ions obtained. Results on the adsorption of MnO4- ions in fixed-bed dynamics obtained on AC-400 and AC-600 adsorbents beds indicated that the AC-400 bed appears to be the most efficient in removing MnO4- ions in acidic media. Indeed, the adsorbed amounts, the adsorbed capacities at saturation and the elimination percentage of MnO4- ions obtained with AC-400 (31.24 mg;52.06 mg·g-1 and 41.65% respectively) were higher compared to those obtained with AC-600 (9.87 mg;16.45 mg·g-1 and 17.79% respectively). The breakthrough curves kinetic modeling revealed that the Thomas model and the pseudo-first-order kinetic model were the most suitable models to describe the adsorption of MnO4- ions on adsorbents studied in our experimental conditions. The results of the intraparticle diffusion model showed that intraparticle diffusion was involved in the adsorption mechanism of MnO4- ions on investigated adsorbents and was not the limiting step and the only process controlling MnO4- ions adsorption. In contrast to AC-400, the intraparticle diffusion on AC-600 bed plays an important role in the adsorption mechanism of MnO4- ions.

Synthesis, Structural Characterization and Antimicrobial Activity of a Novel Cobalt(II) Complex Based on 3-Methyl-1-Phenyl-4-(2-Thienoyl)-Pyrazol-5-One

New cobalt(II) complex, [Co(O2C15H11N2S)2(OH2)2]∙2H2O (1∙2H2O), has been synthesized upon reaction of cobalt chloride hexahydrate (Co(Cl)2∙6H2O) with 3-methyl-1-Phenyl-4-(2-thienoyl)-pyrazol-5-one (referred as HL) in ethanol at room temperature. Single crystal X-ray diffraction (XRD), spectroscopic methods, and microelemental analyses were used to characterize 1∙2H2O. Compound 1∙2H2O crystallizes in the orthorhombic crystal system with a Pbca space group and with the cobalt atom being pseudo-octahedral coordinated. The broth microdilution technique was used to screen the free ligand (HL) and the complex (1∙2H2O) for antimicrobial activities. HL has a low activity (MIC > 100 μg/mL) on all microorganisms, whereas compound 1∙2H2O displayed moderate activity (10 ∙2H2O exhibited bactericidal and fungicidal activity respectively on all the bacteria and yeasts tested. These findings reveal that the antimicrobial activity of HL was enhanced upon coordination to Co(II) ion against all microorganisms (bacteria and fungus).

AGN Lifetimes in UV-selected Galaxies: A Clue to Supermassive Black Hole-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 ~1.5-2,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~1.5-2 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.

Jet Formation Mechanism of the Gamma-Ray-emitting Narrow-line Seyfert 1 Galaxies

We use a large sample of gamma-ray narrow-line Seyfert 1 galaxies(γ-NLS1 s) to study the jet formation mechanisms. We find that the jet power of γ-NLS1 s is lower than the maximum jet power of the Blandford–Payne(BP) mechanism. At the same time, we find that there is a significant correlation between jet power and accretion disk luminosity. Moreover, the contribution rates of the accretion to the jet power are larger than that of black hole mass to jet power. These results further suggest that the jet of γ NLS1 s is mainly produced by the BP mechanism.

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.

Radial stellar populations of AGN-host dwarf galaxies in SDSS-Ⅳ MaNGA survey

Based on MaNGA integral field unit(IFU) spectroscopy we search 60 AGN candidates,which have stellar masses M*≤5 × 10^(9) M⊙ and show AGN ionization signatures in the BPT diagram.For these AGN candidates,we derive the spatially resolved stellar population with the stellar population synthesis code STARLIGHT and measure the gradients of the mean stellar age and metallicity.We find that the gradients of mean stellar age(metallicity) of individual AGN-host dwarfs are diverse in 0-0.5 Re,0.5-1 Re and 0-1 Re.However,the overall behavior of the mean stellar age(metallicity) profiles tend to be flat,as the median values of the gradients are close to zero.We further study the overall behavior of the mean stellar age(metallicity) by plotting the co-added radial profiles for the AGN sample and compare with a control sample with similar stellar mass.We find that the median values of light-weighted mean stellar ages of the AGN sample are as old as 2-3 Gyr within 2 Re,which are about 4-7 times older than those of the control sample.Meanwhile,most of the AGN candidates are low-level AGNs,as only eight sources have L[OⅢ]>1039.5 erg s^(-1).Hence,the AGNs in dwarf galaxies might accelerate the evolution of galaxies by accelerating the consumption of the gas,resulting in an overall quenching of the dwarf galaxies,and the AGNs also become weak due to the lack of gas.The median values of mass-weighted mean stellar age of both samples within 2 Re are similar and as old as about 10 Gyr,indicating that the stellar mass is mainly contributed by old stellar populations.The gradients of co-added mean stellar metallicity for both samples tend to be negative but close to zero,and the similar mean stellar metallicity profiles for both samples indicate that the chemical evolution of the host galaxy is not strongly influenced by the AGN.

Intra-day variability of three Seyfert galaxies measured with XMM-Newton

We present and analyze the variability of three Seyfert galaxies on intra-day timescales. We have analyzed in a uniform manner the 38 longest(> 30 ks) observations made for NGC 4051, MCG-06–30–15 and NGC 4151 by XMM-Newton between 2000 and 2015. The nuclei were quite active during essentially all of these observations and the overall X-ray fluxes(0.3–10 keV) varied by an order of magnitude. Most of the observations do appear to show characteristic timescales, estimated through their auto-correlation functions, ranging between ~2.9 ks and ~45.3 ks. The hard(2–10 keV) and soft(0.3–2.0 keV) bands are very well correlated but consideration of their hardness ratios shows that the sources typically soften during flares. We also provide new estimates of the central black hole masses for these three AGNs that support the hypothesis that Narrow Line Seyfert 1 galaxies have relatively small central black holes.

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 3 CRR radio galaxies selected with a flux density at 178 MHz > 16.4 Jy, 5 GHz very large array(VLA) core flux density≥7 m Jy 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 identified 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 μm 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 10~9 to 10^(13.38) K with a median value of 10^(11.09) K, 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).

On the origin of X-shaped radio galaxies

After a brief,critical review of the leading explanations proposed for the small but important subset of radio galaxies showing an X-shaped morphology (XRGs) we propose a generalized model,based on the jet-shell interaction and spinflip hypotheses.The most popular scenarios for this intriguing phenomenon invoke either hydrodynamical backflows and over-pressured cocoons or rapid jet reorientations,presumably from the spin-flips of central engines following the mergers of pairs of galaxies,each of which contains a supermassive black hole.We confront these models with a number of key observations,and thus argue that none of the models is capable of explaining the entire range of the salient observational properties of XRGs,although some of the arguments raised in the literature against the spin-flip scenario are probably not tenable.We then propose a new scenario which also involves galactic mergers but would allow the spin of the central engine to maintain its direction.Motivated by detailed multi-band observations of the nearest radio galaxy,Centaurus A,this new model emphasizes the role of the interactions between the jets and the shells of stars and gas that form and rotate around the merged galaxy and can cause temporary deflections of the jets,occasionally giving rise to an X-shaped radio structure.Although each model is likely to be relevant to a subset of XRGs,the bulk of the evidence indicates that most of them are best explained by the jet-shell interaction or spin-flip hypotheses.

Soft X-ray Properties of Ultraluminous IRAS Galaxies

We report on the results of cross-correlation of a sample of 903 Ultraluminous IRAS galaxies (ULIRGs) with the ROSAT-All Sky Survey Bright Source Catalogue and the ROSAT archived pointing observations. The sample of ULIRGs has been compiled from the recently released PSCz redshift survey. In total, 35 ULIRGs are securely detected by the ROSAT All-Sky Survey and pointing observations, five of which are blazars. The statistical properties of these sources in the soft X-ray band are determined and compared with their properties in other wavebands. We find that the ratio of the soft X-ray to the far-infrared flux spans about five orders of magnitude and reaches Values of about unity. This ratio is a good indicator of the main energy source of ULIRGs. Those with soft X-ray to far-infrared flux exceeding 0.01 are probably powered by accretion onto central supermassive black holes while those with ratios smaller than 0.001 are probably powered by starbursts or other heating processes, or are Compton thick sources. Some ULIRGs have energy contributions from both. This ratio is low for most ULIRGs and hyperluminous infrared galaxies, which explains their low detection rate by ROSAT and ASCA. We also find that some ULIRGs have a similar soft X-ray luminosity vs. temperature relation to that for groups of galaxies and elliptical galaxies, suggesting a common origin of these systems. Our study also reveals a tight correlation between the hardness ratio and the soft X-ray luminosity for Seyfert 1s/QSOs.

The Variability of Hardness Ratio 1 observed by ROSAT:Narrow-Line Seyfert 1 Galaxies versus Broad-Line Seyfert 1 Galaxies

We examined the correlation between the ROSAT Hardness Ratio 1 and Count Rates eight Narrow-line Seyfert 1 Galaxies (NLS1s) and 14 Broad-line Seyfert 1 Galaxies (BLS1s). We found that six of the NLS1s show a positive HR1-CTs correlation, and seven of the BLS1s, a negative correlation. The other two NLS1s and seven BLS1s do not show any clear HR1-CTs correlation. Thus, the spectral behavior is statistically different for the NLS1s and BLS1s. The different behaviors can possibly be interpreted in terms of a stable ‘soft excess’ that is strong in NLS1s and weak in BLS1s, plus a power law component, common to both, which softens with increasing flux.