CfA Sample Research Articles

Facile Synthesis of CuFe2O4 Nanoparticles for Efficient Removal of Acid Blue 113 and Malachite Green Dyes from Aqueous Media

This work studies the synthesis, characterization, and application of CuFe2O4 nanoparticles for the removal of acid blue 113 and malachite green dyes from aqueous media. Utilizing the combustion procedure, CuFe2O4 nanoparticles were synthesized using two different fuels: L-alanine (CFA) and L-valine (CFV). Besides, the synthesized CuFe2O4 nanoparticles were characterized through some tools, including Fourier transform infrared (FTIR), X-ray diffraction (XRD), energy-dispersive X-ray (EDX), and field emission scanning electron microscope (FE-SEM). XRD analysis verified the creation of a CuFe2O4 cubic spinel structure without any contaminants, revealing average crystallite sizes of 26.37 and 17.65 nm for the CFA and CFV samples, respectively. The FTIR spectra exhibited peaks indicative of metal-oxygen bond stretching, verifying the presence of a spinel formation. Elemental analysis via EDX confirmed the stoichiometric composition typical of copper ferrite. In addition, FE-SEM displayed that the CFA and CFV samples are composed of particles with spherical and irregular shapes, measuring average diameters of 188.35 and 132.78 nm, respectively. The maximum adsorption capabilities of the CFA and CFV samples towards acid blue 113 dyes are 281.69 and 297.62 mg/g, respectively. Also, the maximum adsorption capabilities of the CFA and CFV products towards malachite green dye are 280.11 and 294.99 mg/g, respectively. Kinetic and equilibrium studies revealed that the adsorption process of acid blue 113 and malachite green dyes onto the CFA and CFV samples followed the pseudo-second-order model and Langmuir isotherm. Thermodynamic analysis indicated that the adsorption process was physical, spontaneous, and exothermic.

‘Thermo-mechanical behavior of alternative material combinations for full-arch implant-supported hybrid prostheses with short cantilevers’

ObjectivesTo compare the fracture resistance (FR) of three combinations of materials for full-arch maxillary implant-supported hybrid prostheses (HPs) with short cantilevers (≤ 10 mm). MethodsMaxillary HPs were fabricated and classified as follows (n = 5 each): Group-1 (CC-A, control): acrylic-resin-veneered Co-Cr frameworks; Group-2 (CF-A): acrylic-resin-veneered carbon-fiber mesostructures; and Group-3 (CF-R): composite-resin-veneered carbon-fiber frames. Specimens were thermal-cycled (5,000 cycles; 5 °C–55 °C; dwell time: 30 s). Vertical loads were applied until failure, first at the 10-mm-long cantilever (LC), and, afterwards, at the anterior region (AR), using a universal testing machine (crosshead speed: 0.05 mm/s). The fracture pattern was assessed by stereomicroscope and SEM. The one-way ANOVA, the Bonferroni, and the independent samples t tests, were run (α= 0.05). ResultsAt LC, CF-A, and CC-A samples exhibited the highest FR values (p< 0.001), showing no differences to each other. At AR, CC-A specimens recorded the highest FR, followed by CF-A samples (p< 0.001). CF-R HPs displayed the lowest FR at both locations (p< 0.001). The only group with differences between the tested sites was the CC-A, the AR being more resistant (p< 0.001). Most CC-A and CF-A HPs failed cohesively. CF-R prostheses mainly failed adhesively. ConclusionsMaxillary HPs with short cantilevers (≤ 10 mm) made of Co-Cr or carbon-fiber veneered with acrylic resin demonstrated an adequate mechanical resistance (> 900 N). Clinical significanceFor maxillary HPs with cantilevers up to 10 mm, acrylic-veneered carbon- fiber mesostructures may be recommended, whereas coating carbon-fiber frames with composite resin seems not suitable.

A factor analytic evaluation of the Self-Stigma Scale-Short (SSS-S) among psychosocial clubhouse members in the United States

The main purpose of this study was to examine the factor structure, the internal consistency, and other aspects of validity of the English version of the Self-Stigma Scale-Short (SSS-S). In the present study, the SSS-S was assessed in a sample of 194 adults with psychiatric disabilities from four Psychosocial Clubhouses in the Southern and Midwestern United States. Exploratory factor analysis (EFA; n = 98) supported a one-factor structure of the SSS-S, which accounted for 59% of the variance. Confirmatory factor analysis (CFA; n = 96) demonstrated that the factor structure of the SSS-S was satisfactory. The scale was also reliable, with a Cronbach's alpha of 0.93 and 0.91 for the EFA and CFA samples, respectively. The SSS-S showed adequate convergent and criterion-related validity, as indicated by statistically significant positive correlations between internalized stigma with perceived societal stigma, symptom severity, and functional impairment, as well as negative correlations between internalized stigma with perceived social self-efficacy, social support, and resiliency. Overall, these findings support the English version of the SSS-S as a valid and reliable tool for determining the internalized stigma of adults with psychiatric disabilities in clinical settings and similar research.

A Malinchismo Scale for Use among Adolescents

Malinchismo is a recently documented concept referring to preferencing the culture, ideas, tastes and behaviors of another nation/culture over one’s own. First, we introduce this new concept in relation to post-colonial theory, social identity theory, and remote acculturation theory, explaining its relevance to adolescent development. We then introduce and validate a new Malinchismo scale using a derivative sequential method among two samples of adolescents in Mexico (n = 560 total). Our Malinchismo Scale is more comprehensive than existing alternatives and is the first to be validated for use among adolescents. We assessed 1) content validity using the responses of content experts who served as judges, 2) construct validity using exploratory and confirmatory factor analyses (EFA and CFA, respectively), and 3) convergent and discriminant validity using participant responses to the Ingroup Interethnic Bias Test. In total, 366 adolescents were in the EFA sample (M=16.18 years, SD=0.74, 62% female) and 194 adolescents were in the CFA sample (M=16.17, SD=1.06, 57% female). Results revealed excellent psychometric properties on all indices, supporting the Malinchismo Scale as a valid and reliable measure for adolescents.

Do Demographic Traits Matter? Backpackers’ Information Technology and Destination-Related Risk Concerns Towards Smartphone Usage

&#x0D; &#x0D; &#x0D; A number of risks are associated with the use of mobile phones. However, there is still a paucity of evidence on the extent to which demographics influence risk perceptions of smartphone usage. This paper examines backpackers’ perceived risk of smartphone usage and the extent to which demographic attributes influence risk perceptions. A survey involving 567 backpackers was conducted in Ghana. The CFA, ANOVA and independent samples t-test were used to analyse the data. The study showed the relevance of coalescing information technology and destination risks factors in measuring perceived risks towards smartphone usage before assessing the effects of demographics on perceived risk. Importantly, backpackers’ risk perceptions are a function of their demographic traits, such as sex, age, education, income, occupation, continent of origin and travel experience. The theoretical and managerial implications of the study are discussed.&#x0D; &#x0D; &#x0D;

Alabama Parenting Questionnaire—Short Form (APQ-9): Evidencing Construct Validity with Factor Analysis, CFA MTMM and Measurement Invariance in a Greek Sample

This study focused on the factor structure, measurement invariance, reliability, and validity of the Greek version of APQ-9 in a sample of 621 parents of children aged 7 - 13 years. The factor structure was examined first with EFA in the 30% subsample and CFA in the rest 70%. Power analysis indicated adequate CFA sample power at 80% probability of rejecting a false null hypothesis. The original structure of APQ-9 was verified. Full measurement in-variance was also examined across child gender to a strict level. Convergent and discriminant validity of APQ-9 parenting practices were evaluated by the CFA MTMM framework with a model of three traits and three methods. Convergent and discriminant validity was also evaluated further with correlation analysis. A consistent pattern of correlations emerged by examining five parenting measures with 13 dimensions of parenting. APQ-9 has also adequate internal consistency and factor-based reliability and validity (α, ω, and AVE).

Applied Psychometrics: The 3-Faced Construct Validation Method, a Routine for Evaluating a Factor Structure

The “3-faced construct validation method” is a routine for establishing the validity and reliability of an existing scale when adapted in a different cultural context from the context initially developed. This routine can also be used for the initial validation of a newly developed scale. This is essentially a construct validation procedure based on a sample-splitting. The sample is randomly split into three parts, 20% for EFA, 40% for an exploratory CFA and 40% for a cross-validating CFA. The cases per variable threshold is set above 5:1, preferably above 10:1 (minimum conditions) and the first approximately 20% subsample emerges (adequate conditions) to evaluate EFA and Bifactor EFA models. Then the cases per variable threshold is set above 10:1, preferably above 20:1 (minimum conditions) and the 40% subsample emerges (adequate conditions) to examine alternative CFA models (ICM-CFA, Bifactor CFA, ESEM and Bifactor ESEM models). The optimal model(s) is cross-validated by a second CFA in yet another 40% subsample (equal-power CFA sample) as a protection against overfitting (over-optimization) to safeguard model replicability. Measurement invariance follows and is essentially another cross-check of the optimal model over the entire sample because the optimal model is used as the baseline model.

Psychometric Evaluation of the IBD-Specific Anxiety Scale: A Novel Measure of Disease-Related Anxiety for Adolescents With IBD.

The present study will report the preliminary validation of the 20-item IBD-Specific Anxiety Scale (IBD-SAS) in a large, geographically diverse sample of adolescents aged 12-18 years with IBD. A total of 281 adolescents, ages 12-18 (M = 14.8, SD = 1.78; 51% male), completed the IBD-SAS along with measures of IBD-related quality of life, anxiety, depressive symptoms, and disease activity. Factor structure was assessed using exploratory and confirmatory factor analyses (EFA and CFA). EFA (Sample 1; n = 141) yielded one-, two-, three- and four-factor models. The CFA (Sample 2; n = 140) demonstrated that a four-factor model was superior to three- and two-factor model for the amended scale. In total, the IBD-SAS showed excellent internal consistency (Cronbach's α = .95) and was most strongly associated with health-related quality of life. Moderate to strong associations were observed between IBD-SAS and general measures of anxiety and depressive symptoms, and IBD disease activity providing additional support that health-specific anxiety is a valid and distinct construct. Based on the results of this study, the IBD-SAS displayed adequate psychometric properties and can meaningfully contribute to the assessment of IBD-specific anxiety in adolescents diagnosed with IBD, thus filling an empirical and clinical need in this population.

Biofield Energy Treatment: A Potential Strategy for Modulating Physical, Thermal and Spectral Properties of 3-Chloro-4-fluoroaniline

3-Chloro-4-fluoroaniline (CFA) is used as an intermediate for the synthesis of pharmaceutical compounds. The objective of this study was to investigate the influence of biofield energy treatment on the physical, thermal and spectral properties of CFA. The study was performed in two groups (control and treated). The control group remained as untreated, and the treated group received Mr. Trivedi’s biofield energy treatment. The control and treated CFA samples were further characterized by x-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), fourier transform infrared (FT-IR) spectroscopy, and ultra violet-visible spectroscopy (UV-vis) analysis. The XRD analysis of treated CFA showed significant changes in the intensity of peaks as compared to the control. However, the average crystallite size (G) was significantly decreased by 22.08% in the treated CFA with respect to the control. The DSC analysis showed slight decrease in the melting temperature of treated CFA (47.56°C) as compared to the control (48.05°C). However, the latent heat of fusion in the treated sample was considerably changed by 4.28% with respect to the control. TGA analysis showed increase in maximum thermal decomposition temperature (Tmax) of the treated sample (163.34°C) as compared to the control sample (159.97°C). Moreover the onset temperature of treated CFA (148 °C) was also increased as compared to the control sample (140°C). Additionally, the weight loss of the treated sample was reduced (42.22%) with respect to the control (56.04%) that may be associated with increase in thermal stability. The FT-IR spectroscopic evaluation showed emergence of one new peak at 3639 cm-1 and alteration of the N-H (stretching and bending) peak in the treated sample as compared to the control. Overall, the result demonstrated that Mr. Trivedi’s biofield energy treatment has paramount influence on the physical, thermal and spectral properties of CFA.

Exploratory and confirmatory factor analyses of the WISC-IV with gifted students.

These 2 studies investigated the factor structure of the Wechsler Intelligence Scale for Children-4th edition (WISC-IV; Wechsler, 2003a) with exploratory factor analysis (EFA; Study 1) and confirmatory factor analysis (CFA; Study 2) among 2 independent samples of gifted students. The EFA sample consisted of 225 children who were referred for a cognitive assessment as part of the application for gifted programming in their schools. The CFA sample consisted of 181 students who were tested the following year. All students included in the analyses were either accepted to school-based gifted programs following the assessment or were already participating in one. Across the 2 studies, there were approximately equal numbers of boys (205) and girls (201) with a mean age of 8-years-old. The mean composite scores for both samples varied from high average to superior and evidenced substantial differences among the index scores. In the EFA, the 2-, 3-, 4-, and 5-factor solutions were considered. The first 3 models, as well as an additional model reflecting the Verbal and Performance (V-P) IQ scores from previous versions of the WISC, were then compared using CFA. The CFA fit indices and parameter estimates supported the 4-factor, first-order WISC-IV model. This is the measurement model that includes the 4 index scores. Parameter estimates for the higher-order model reflecting g suggested that combining factors into a single, overarching score may not be the best way to represent the varying cognitive scores of gifted students.

The Far-Infrared Properties of the Most Isolated Galaxies

AbstractWe describe the mid- (MIR) and far- (FIR) infrared properties of a large (~1000) sample of the most isolated galaxies in the local Universe. This sample is intended as a “nurture-free” zero point against which more environmentally influenced samples can be compared. We reprocess IRAS MIR/FIR survey data using the ADDSCAN/SCANPI utility for 1030 out of 1050 galaxies from the Catalogue of Isolated Galaxies (CIG) as part of the AMIGA project. We focus on diagnostics (FIR luminosity LFIR, R = log(LFIR/LB) and IRAS colours) thought to be sensitive to effects of environment or interaction. The distribution of log(LFIR) is sharply peaked from 9.0–10.5 with very few (&lt;2%) galaxies above 10.5. Review of available optical images of the most FIR luminous galaxies finds the majority to be, likely, interacting systems missed in our earlier morphological reevaluation. The optically normalised luminosity diagnostic R = log(LFIR/LB) shows a distribution sharply peaked between 0.0 and −1.0. These results were compared to the magnitude limited CfA sample that was selected without environmental discrimination. This modestly (e.g. compared to cluster, binary galaxy and compact group samples) environmentally affected sample shows significantly higher mean log(LFIR) and R, whereas the mean log(LB) is the same. Our sample shows a strong LFIR vs. LB correlation, with a slope steeper than one (LFIR ∝ L1.41B). Interacting galaxies were found above this correlation, showing an enhancement in LFIR. With respect to the IRAS colours, we found higher F60/F100 value for ellipticals and late-type galaxies than for spirals, indicating a higher dust temperature. The mean value of F60/F100 was found to be lower than for interacting samples from the literature. The results indicate that the FIR emission is a variable enhanced by interaction, and that our sample probably shows the lowest possible mean value. This attests to the utility of our sample for defining a nurture-free zero point. More details can be found in the paper (The AMIGA sample of isolated galaxies, III. IRAS data and infrared diagnositics, U. Lisenfeld et al.) which is accepted for publication in Astronomy &amp; Astrophysics.

Spectral Energy Distributions of Seyfert Nuclei

We present nuclear spectral energy distributions (SEDs) in the range 0.4–16 μm for an expanded CfA sample of Seyfert galaxies. The spectral indexes (fν ∝ ν) from 1 to 16 μm range from αIR ∼ 0.9 to 3.8. The shapes of the spectra are correlated with Seyfert type in the sense that steeper nuclear SEDs (νfν increasing with increasing wavelength) tend to be found in Seyfert 2's, and flatter SEDs (νfν is constant) in Seyfert 1–1.5's. The galaxies optically classified as Seyferts 1.8's and 1.9's display values of αIR as in type 1 objects, or values intermediate between those of Seyfert 1's and Seyfert 2's. The intermediate SEDs of many Seyfert 1.8–1.9's may be consistent with the presence of a pure Seyfert 1 viewed through a moderate amount (AV ≲ 5 mag) of foreground galaxy extinction. We find, however, that between 10% and 20% of galaxies with broad optical line components have steep infrared SEDs. Torus models usually adopt high equatorial opacities to reproduce the infrared properties of Seyfert 1's and 2's, resulting in a dichotomy of infrared SEDs (flat for type 1's, and steep for type 2's). Such a dichotomy, however, is not observed in our sample. The wide range of spectral indexes observed in the type 2 objects, the lack of extremely steep SEDs, and the large numbers of objects with intermediate spectral indexes cannot be reconciled with predictions from existing optically thick torus models. We discuss possible modifications to improve torus models, including low optical depth tori, clumpy dusty tori, and high optical depth tori with an extended optically thin component.

Seyfert and Starburst Activity in Galaxies: Modeling and Analysis

During recent years, there has been a growing interest in active galactic nuclei and starburst galaxies. These two spectacular phenomena can dominate completely the total spectrum of their host, and they are present in a significant fraction of the local galaxy population. There is growing evidence that they might play an important part in the galaxy evolution at high redshift (e.g., A. Dey et al. 1997, ApJ, 490, 698; A. Cimatti et al. 1999, A&A, 352, L45), prompting us to carry out a detailed study of nearby galaxies with active nuclei and starbursts in order to take advantage of the more detailed analysis that can be carried out in the local universe. Seyfert galaxies.—We used new infrared (IR) spectroscopy of the CO band at 2.3 mm of 46 Seyfert galaxies from the CfA sample (J. Huchra & R. Burg, 1992, ApJ, 393, 90) to constrain the populations of young stars in their central regions. This is the first set of IR spectra of a complete sample of Seyfert galaxies. The CO band appears diluted by a nonstellar featureless component, most likely warm dust near the central engine. We devised a technique based on JHKL colors to separate the stellar and nonstellar components at 2.3 mm and corrected 16 Seyfert galaxies for dilution. A comparison with the CO indices of ellipticals and pure starburst galaxies indicates that no red supergiant phase starbursts dominate the Seyfert galaxies currently. The best Seyfert-starburst separator in the near-IR appears to be the [Fe ii] (1.26 mm)/Pab versus H2 (2.12 mm)/Brg diagram. The narrow emission line properties of our sample are significantly different from those of ultraluminous IR galaxies from the sample of T. W. Murphy, Jr., et al. (2001, AJ, 121, 97), implying that most of the latter (∼ ) cannot contain 23 hidden active nuclei. The other ∼ can still harbor completely 13 obscured AGNs, invisible even in the K band. Spectral library.—We have compiled a moderately high resolution ( ) H(1.6 mm) and K-band (2.2 mm) R ≈ 2000–3000 spectral atlas containing 218 stars. The atlas spans most of the ranges of , and [Fe/H] relevant for modeling starburst T log g, eff galaxies. We report indices for 19 spectral features and develop new diagnostic techniques for estimating parameters of individual stars. Magnesium indices are the best near-IR metallicity indicators because they are less sensitive to the stellar than Teff the others. The IR Mg i indices are just as good indicators for the abundance in composite systems as their optical counterparts. We have calibrated the strength of Mg i at 1.50 mm as function of the stellar [Fe/H]. We also calibrated a number of line ratios as indicators and luminosity class separators. Teff Despite the lack of suitable iron lines, the light-to-heavy element abundance ratio can be estimated in the IR by using the Ca i at 2.26 mm, because it has been shown from optical observations (G. Worthey 1998, PASP, 110, 888) that the calcium abundance follows the iron abundance. Evolutionary population synthesis.—The spectral library was incorporated into an evolutionary population synthesis model for young stellar populations (≤30 Myr) aimed specifically at starbursts. The model is based on Starburst99, developed by C. Leitherer et al. (1999, ApJ, 123, 3). It predicts the time evolution of near-IR features for single bursts of star formation (SF). They all are very weak during the first 5–7 Myr, while most of the flux comes from hot blue supergiants. The indices become stronger as the red supergiants begin to develop at 7–10 Myr. The indices weaken as the supergiants explode as supernovae at 12–15 Myr and stabilize at to 13 of the peak values after that. Our models, when combined 12 with age estimates from hydrogen recombination emission lines, can be used to probe directly the abundance of the starbursts, because the index strengths are scaled by the metallicity. Metallicities of starbursts.—We applied the Mg i 1.50 mm indicator to determine the metallicity of the starbursts from C. Engelbracht (1997, Ph.D. thesis, Univ. Arizona) and derived near-solar abundances for the majority of them. The technique yielded [Fe/H] p 0.3–0.4 for giant ellipticals. Our estimates correlate very well with the optical iron indices. We demonstrated by means of a simple chemical enrichment model that the fraction of iron peak elements can be influenced significantly by the preceding SF history. This poses a problem for [Fe/H] estimates based on a-elements (e.g., Mg) but also opens up a possibility to explore the previous SF history.

MERLIN radio observations of CfA Seyferts

We present new 1.6-GHz (18-cm) MERLIN maps of 15 Seyfert galaxies, with angular resolutions typically 0.1 to 0.3 arcsec. These and previous observations are used to investigate the properties of 19 of the 24 CfA Seyfert galaxies brighter than 2 mJy at 8.4 GHz. This is the first time a significant fraction of the CfA sample has been mapped at this frequency with subarcsecond resolution, and our observations provide the highest resolution radio maps available for several sources. We use our observations to measure the two-point spectral indices of compact radio components, and we investigate the correlation between infrared and radio emission shown by Seyfert galaxies. Our results can be summarized as follows. Resolved structures as small as 20 pc are found in three previously unresolved radio sources, and only four sources show single, unresolved radio components. The mean 1.6 to 8.4 GHz spectral index of 31 radio components is , and approximately 25 per cent of the components have a spectral index flatter than . The spectral index distributions of type 1 and type 2 Seyferts are statistically indistinguishable. The cores of multiple-component sources tend to have flatter radio spectra than secondary components. The low-resolution infrared (IRAS) emission from Seyfert galaxies is usually dominated by kiloparsec-scale, extranuclear emission regions.

Research Note On the relation between the IR continuum and the active galactic nucleus in Seyfert galaxies

A sample of the brightest known Seyfert galaxies from the CfA sample is analyzed on the basis of ISO photometric and spectroscopic data. Regardless of the Seyfert type, the mid-IR continuum emission from these galaxies is found to be correlated with the coronal line emission arising in the nuclear active region. Conversely, the correlation degrades progressively when moving from the mid- to the far-IR emission, where it ends to vanish. It is concluded that the mid-IR emission is largely dominated by dust heated by processes associated with the active nucleus whereas the far-IR is a different component most probably unrelated with the active region. We suggest that the far-IR component is due to dust heated by the stellar population in the disks of these galaxies.

On the Ionizing Continuum in Active Galactic Nuclei: Clues from theInfrared Space Observatory

The ISO coronal line spectrum of the brightest Seyfert galaxies from the CfA sample is presented and modeled. ISO observations of [O IV] 25.9 $\mu$, [Ne V] 14.3 $\mu$, [Mg VIII] 3.02 $\mu$ and [Si IX] 2.58 $\mu$ lines are presented; their relationship with the soft part of the ionizing spectrum from 50 to 300 eV is investigated. Pure photoionization models reproduce the line ratios, setting ranges for the ionization parameter and the optical depth of the emitting clouds. On the basis of the available data alone it is not possible to distinguish between a power-law or a blackbody distribution as the intrinsic shape of the UV ionizing spectrum. However, for the brightest Seyferts analyzed, namely, NGC 1068, Circinus and NGC 4151, a black-body UV continuum is favored.

A Subarcsecond Resolution Near‐Infrared Study of Seyfert and “Normal” Galaxies. II. Morphology

We present a detailed study of the bar fraction in the CfA sample of Seyfert galaxies, and in a carefully selected control sample of non-active galaxies, to investigate the relation between the presence of bars and of nuclear activity. To avoid the problems related to bar classification in the RC3, e.g., subjectivity, low resolution and contamination by dust, we have developed an objective bar classification method, which we conservatively apply to our new sub-arcsecond resolution near-infrared imaging data set (Peletier et al. 1999). We are able to use stringent criteria based on radial profiles of ellipticity and major axis position angle to determine the presence of a bar and its axial ratio. Concentrating on non-interacting galaxies in our sample for which morphological information can be obtained, we find that Seyfert hosts are barred more often (79% +/- 7.5%) than the non-active galaxies in our control sample (59% +/- 9%), a result which is at the 2.5 sigma significance level. The fraction of non-axisymmetric hosts becomes even larger when interacting galaxies are taken into account. We discuss the implications of this result for the fueling of central activity by large-scale bars. This paper improves on previous work by means of imaging at higher spatial resolution and by the use of a set of stringent criteria for bar presence, and confirms that the use of NIR is superior to optical imaging for detection of bars in disk galaxies.

The Radio Properties of Seyfert Galaxies in the 12 Micron and CfA Samples

We report the results of 20, 6, and 2 cm VLA and 1.5 cm OVRO observations of two similar radio-quiet active galaxy and quasar (AGN) samples: the optically selected CfA Seyfert galaxies and the bolometric flux-limited 12 μm active galaxy sample. Every object observed was detected at 6 cm. Only ~6%-8% of the 12 μm sample Seyfert galaxies (three to four objects) are radio-loud (and none of the CfA sample), as compared to 15%-20% for the Bright Quasar Survey quasars. These radio-loud objects are compact and have flat spectra, distinguishing them from the more common radio-quiet objects.The 6-20 cm slopes of the Seyfert 1's and 2's are similar, with average values of α620 cm = -0.66 and -0.71, respectively. Although several Seyfert 1's are significantly flatter than this in their 6-20 and/or 1.5-6 cm slopes, there is no systematic trend for either Seyfert type to display upward or downward spectral curvature.Excluding the radio-loud quasars, the integrated 6 cm radio luminosity is linearly proportional to the 60 μm luminosity over several orders of magnitude, with on average twice the radio power of normal spirals of the same far-infrared power. About half of the objects show extended 6 cm emission, contributing on average 33% of the total flux. Thus the luminosities of these extended components alone are comparable to normal spirals of similar infrared luminosities.The 12 μm sample radio luminosity function is slightly higher than that of the CfA sample. The integrated space density of Seyfert 2's is ~2 times that of Seyfert 1's over their common range in luminosity. In terms of the standard unified model, this ratio in space density corresponds to a typical half-angle of the torus of θ~ 48°.

Soft X‐Ray Properties of Seyfert Galaxies in the ROSAT All‐Sky Survey

We present the results of ROSAT All-Sky Survey observations of Seyfert and IR luminous galaxies from the extended 12 μm galaxy sample and the optically selected CfA sample. Detections are available for 80% (44/55) of the Seyfert 1's and 34% (23/67) of the Seyfert 2's in the 12 μm sample, and for 76% (26/34) of the Seyfert 1's and 38% (6/16) of the Seyfert 2's in the CfA Sample. Roughly half of the Seyfert galaxies (mostly Seyfert 1's) have been fitted to an absorbed power-law model, yielding an average photon index of Γ = 2.26 ± 0.11 for 43 Seyfert 1's and Γ = 2.45 ± 0.18 for 10 Seyfert 2's, with both types having a median value of 2.3. The soft X-ray luminosity corelates with the 12 μm luminosity, with Seyfert 1's, having relatively more soft X-ray emission than Seyfert 2's of similar mid-IR luminosities by factor of 1.6 ± 0.3. Several physical interpretaions of these results are discused, including the standard unified model for Seyfert galaxies. Infrared luminous non-Seyferts are shown to have similar disributions of soft X-ray luminosity and X-ray-to-IR slope as Seyfert 2's suggesting that some of them may harbor obscured active nuclei (as has already ben shown to be true for several objects) and/or that the soft X-rays from some Seyfert 2's may be nonnuclear. A soft X-ray luminosity function (XLF) is calculated for the 12 μm sample, which is described well by a single power law with a slope of −1.75. The normalization of this XLF agrees well with that of a hard X-ray selected sample. Several of our results, related to the XLF and the X-ray-to-IR relation, are shown to be consistent with the hard x-ray observations of the 12 μm sample by barcons et al.

Large-scale structure in a new deep IRAS galaxy redshift survey

We present here the first results from two recently completed, fully sampled redshift surveys comprising 3703 IRAS Faint Source Survey (FSS) galaxies. An unbiased counts-in-cells analysis finds a clustering strength in broad agreement with other recent redshift surveys and at odds with the standard cold dark matter model. We combine our data with those from the QDOT and 1.2 Jy surveys, producing a single estimate of the IRAS galaxy clustering strength. We compare the data with the power spectrum derived from a mixed dark matter universe. Direct comparison of the clustering strength seen in the IRAS samples with that seen in the APM-Stromlo survey suggests b_O/b_I=1.20+/-0.05 assuming a linear, scale independent biasing. We also perform a cell by cell comparison of our FSS-z sample with galaxies from the first CfA slice, testing the viability of a linear-biasing scheme linking the two. We are able to rule out models in which the FSS-z galaxies identically trace the CfA galaxies on scales 5-20h^{-1}Mpc. On scales of 5 and 10h^{-1}Mpc no linear-biasing model can be found relating the two samples. We argue that this result is expected since the CfA sample includes more elliptical galaxies which have different clustering properties from spirals. On scales of 20h^{-1}Mpc no linear-biasing model with b_O/b_I < 1.70 is acceptable. When comparing the FSS-z galaxies to the CfA spirals, however, the two populations trace the same structures within our uncertainties.