- ID:
- ivo://CDS.VizieR/J/ApJS/238/37
- Title:
- Opt. & NIR spectral atlas of 16 2MASS NIR-red AGNs
- Short Name:
- J/ApJS/238/37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present medium-resolution spectra (R~2000-4000) at 0.4-1.0{mu}m and 0.7-2.5{mu}m of 16 active galactic nuclei (AGNs) selected with red color in the near-infrared (NIR) of J-K>2.0mag at z~0.3. We fit the H{beta}, H{alpha}, P{beta}, and P{alpha} lines from these spectra to obtain their luminosities and line widths. We derive the E(B-V) color excess values of the NIR-red AGNs using two methods, one based on the line-luminosity ratios and another based on the continuum slopes. The two E(B-V) values agree with each other at rms dispersion ~0.249. About half of the NIR-red AGNs have g'-K<5 magnitude, and we find that these NIR-red, but blue in optical-NIR AGNs, have E(B-V)~0, suggesting that a significant fraction of the NIR color-selected red AGNs are unobscured or only mildly obscured. After correcting for the dust extinction, we estimate the black hole (BH) masses and the bolometric luminosities of the NIR-red AGNs using the Paschen lines to calculate their Eddington ratios ({lambda}Edd). The median Eddington ratios of nine NIR-red AGNs (log({lambda}_Edd_~-0.654+/-0.176) are only mildly higher than those of unobscured type 1 AGNs (log({lambda}_Edd_~-0.961+/-0.008). Moreover, we find that the MBH-{sigma}* relation for three NIR-red AGNs is consistent with that of unobscured type 1 AGNs at similar redshift. These results suggest that the NIR-red color selection alone is not effective at picking up dusty, intermediate-stage AGNs.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/454/3864
- Title:
- Orientation & QSO black hole mass estimation
- Short Name:
- J/MNRAS/454/3864
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have constructed a sample of 386 radio-loud quasars with z<0.75 from the Sloan Digital Sky Survey in order to investigate orientation effects on black hole mass estimates. Orientation is estimated using radio core dominance measurements based on FIRST survey maps. Black hole masses are estimated from virial-based scaling relationships using H{beta}, and compared to the stellar velocity dispersion ({sigma}*), predicted using the full width at half maximum (FWHM) of [OIII] {lambda}5007, which tracks mass via the M-{sigma}* relation. We find that the FWHM of H{beta} correlates significantly with radio core dominance and biases black hole mass determinations that use it, but that this is not the case for {sigma}* based on [OIII] {lambda}5007. The ratio of black hole masses predicted using orientation-biased and unbiased estimates, which can be determined for radio-quiet as well as radio-loud quasars, is significantly correlated with radio core dominance. Although there is significant scatter, this mass ratio calculated in this way may in fact serve as an orientation estimator. We additionally note the existence of a small population of radio core-dominated quasars with extremely broad H{beta} emission lines that we hypothesize may represent recent black hole mergers.
- ID:
- ivo://CDS.VizieR/J/AJ/155/188
- Title:
- Origin of nuclear activity in low-power radio galaxies
- Short Name:
- J/AJ/155/188
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using large samples containing nearly 2300 active galaxies of low radio luminosity (1.4 GHz luminosity between 2x10^23^ and 3x10^25^ W/Hz, essentially low-excitation radio galaxies) at z~<0.3, we present a self-contained analysis of the dependence of the nuclear radio activity on both intrinsic and extrinsic properties of galaxies, with the goal of identifying the best predictors of the nuclear radio activity. While confirming the established result that stellar mass must play a key role on the triggering of radio activities, we point out that for the central, most massive galaxies, the radio activity also shows a strong dependence on halo mass, which is not likely due to enhanced interaction rates in denser regions in massive, cluster-scale halos. We thus further investigate the effects of various properties of the intracluster medium (ICM) in massive clusters on the radio activities, employing two standard statistical tools, principle component analysis and logistic regression. It is found that ICM entropy, local cooling time, and pressure are the most effective in predicting the radio activity, pointing to the accretion of gas cooling out of a hot atmosphere to be the likely origin in triggering such activities in galaxies residing in massive dark matter halos. Our analysis framework enables us to logically discern the mechanisms responsible for the radio activity separately for central and satellite galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/658/A12
- Title:
- Origins of radio emission in NLS1s
- Short Name:
- J/A+A/658/A12
- Date:
- 02 Feb 2022 14:01:48
- Publisher:
- CDS
- Description:
- Narrow-line Seyfert 1 galaxies (NLS1s) are believed to be active galactic nuclei (AGN) in the early stages of their evolution. Several dozen of them have been found to host relativistic jets, whilst the majority of NLS1s have not even been detected in radio, emphasising the heterogeneity of the class in this band. In this paper, our aim is to determine the predominant source of radio emission in a sample of 44 NLS1s, selected based on their extended kiloparsec-scale radio morphologies at 5.2GHz. We accomplish this by analysing their spatially resolved radio spectral index maps, centred at 5.2 GHz, as the spectral index carries information about the production mechanisms of the emission. In addition, we utilise several diagnostics based on mid-infrared emission to estimate the star formation activity of their host galaxies. These data are complemented by archival data to draw a more complete picture of each source. We find an extraordinary diversity among our sample. Approximately equal fractions (~10-12 sources) of our sources can be identified as AGN-dominated, composite, and host-dominated. Among the AGN-dominated sources are a few NLS1s with very extended jets, reaching distances of tens of kiloparsecs from the nucleus. One of these, J0814+5609, hosts the most extended jets found in an NLS1 so far. We also identify five NLS1s that could be classified as compact steep-spectrum sources. In addition, one source shows a possible kiloparsec-scale relic that reaches well outside the host galaxy as well as restarted nuclear activity, and one could belong to the sub-class of NLS1s that host relativistic jets that seem to be absorbed at lower radio frequencies (<10GHz). We further conclude that, due to the variety seen in NLS1s, simple proxies, such as the star formation diagnostics also employed in this paper and the radio loudness parameter, are not ideal tools for characterising NLS1s. We emphasise the necessity of examining NLS1s as individuals instead of making assumptions based on their classification. When these issues are properly taken into account, NLS1s offer an exceptional environment for studying the interplay between the host galaxy and several AGN-related phenomena, such as jets and outflows.
- ID:
- ivo://CDS.VizieR/J/MNRAS/469/4565
- Title:
- Overdensities of submm-galaxies around AGNs
- Short Name:
- J/MNRAS/469/4565
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate extremely luminous dusty galaxies in the environments around Wide-field Infrared Survey Explorer (WISE)-selected hot dust-obscured galaxies (Hot DOGs) and WISE/radio-selected active galactic nuclei (AGNs) at average redshifts of z=2.7 and 1.7, respectively. Previous observations have detected overdensities of companion submillimetre-selected sources around 10 Hot DOGs and 30 WISE/radio AGNs, with overdensities of ~2-3 and ~5-6, respectively. We find that the space densities in both samples to be overdense compared to normal star-forming galaxies and submillimetre galaxies (SMGs) in the Submillimetre Common-User Bolometer Array 2 (SCUBA-2) Cosmology Legacy Survey (S2CLS). Both samples of companion sources have consistent mid-infrared (mid-IR) colours and mid-IR to submm ratios as SMGs. The brighter population around WISE/radio AGNs could be responsible for the higher overdensity reported. We also find that the star formation rate densities are higher than the field, but consistent with clusters of dusty galaxies. WISE-selected AGNs appear to be good signposts for protoclusters at high redshift on arcmin scales. The results reported here provide an upper limit to the strength of angular clustering using the two-point correlation function. Monte Carlo simulations show no angular correlation, which could indicate protoclusters on scales larger than the SCUBA-2 1.5-arcmin scale maps.
- ID:
- ivo://CDS.VizieR/J/MNRAS/415/1597
- Title:
- PACO catalogue of bright sources
- Short Name:
- J/MNRAS/415/1597
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Planck Australia Telescope Compact Array (Planck-ATCA) Co-eval Observations (PACO) have provided flux density measurements of well-defined samples of Australia Telescope 20GHz (AT20G) radio sources at frequencies below and overlapping with Planck frequency bands, almost simultaneously with Planck observations. We have observed with the ATCA a total of 482 sources in the frequency range between 4.5 and 40GHz in the period between 2009 July and 2010 August. Several sources were observed more than once. In this paper we present the aims of the project, the selection criteria, and the observation and data reduction procedures.
- ID:
- ivo://CDS.VizieR/J/MNRAS/416/559
- Title:
- PACO faint sources catalog
- Short Name:
- J/MNRAS/416/559
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Planck-ATCA Coeval Observations (PACO) project collected data between 4.5 and 40GHz for 482 sources selected within the Australia Telescope 20GHz (AT20G) catalogue and observed with the Australia Telescope Compact Array. Observations were done almost simultaneously with the Planck satellite, in the period between 2009 July and 2010 August. In this paper, we present and discuss the data for the complete sample of 159 sources with S_AT20G_>200mJy in the South Ecliptic Pole region.
- ID:
- ivo://CDS.VizieR/J/MNRAS/465/4085
- Title:
- PACO radio sources complete sample polarimetry
- Short Name:
- J/MNRAS/465/4085
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-sensitivity polarimetric observations ({sigma}_P_~=0.6mJy) in six bands covering the 5.5-38GHz range of a complete sample of 53 compact extragalactic radio sources brighter than 200mJy at 20GHz. The observations, carried out with the Australia Telescope Compact Array, achieved a 91 per cent detection rate (at 5{sigma}). Within this frequency range, the spectra of about 95 per cent of sources are well fitted by double power laws, both in total intensity and in polarization, but the spectral shapes are generally different in the two cases. Most sources were classified as either steep- or peaked-spectrum but less than 50 per cent have the same classification in total and in polarized intensity. No significant trends of the polarization degree with flux density or with frequency were found. The mean variability index in total intensity of steep-spectrum sources increases with frequency for a 4-5yr lag, while no significant trend shows up for the other sources and for the 8yr lag. In polarization, the variability index, which could be computed only for the 8yr lag, is substantially higher than in total intensity and has no significant frequency dependence.
- ID:
- ivo://CDS.VizieR/J/MNRAS/428/1845
- Title:
- PACO spectrally selected sample
- Short Name:
- J/MNRAS/428/1845
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Planck Australia Telescope Compact Array (Planck-ATCA) Co-eval Observations (PACO) have provided multi-frequency (5-40GHz) flux density measurements of complete samples of Australia Telescope 20GHz (AT20G) radio sources at frequencies below and overlapping with Planck frequency bands, almost simultaneously with Planck observations. In this work we analyse the data in total intensity for the spectrally selected PACO sample, a complete sample of 69 sources brighter than S20GHz=200mJy selected from the AT20G survey catalogue to be inverted or upturning between 5 and 20GHz. We study the spectral behaviour and variability of the sample. We use the variability between AT20G (2004-2007) and PACO (2009-2010) epochs to discriminate between candidate High-Frequency Peakers (HFPs) and candidate blazars. The HFPs picked up by our selection criteria have spectral peaks >10GHz in the observer frame and turn out to be rare (<0.5% of the S20GHz>=200mJy sources), consistent with the short duration of this phase implied by the "youth" scenario. Most (=~89%) of blazar candidates have remarkably smooth spectra, well described by a double power law, suggesting that the emission in the PACO frequency range is dominated by a single emitting region. Sources with peaked PACO spectra show a decrease of the peak frequency with time at a mean rate of -3+/-2GHz/yr on an average time-scale of <{tau}>=2.1+/-0.5yr (median: {tau}median=1.3yr). The 5-20GHz spectral indices show a systematic decrease from AT20G to PACO. At higher frequencies spectral indices steepen: the median {alpha}4030 is steeper than the median {alpha}205 by {delta}{alpha}=0.6. Taking further into account the Wide-field Infrared Survey Explorer data we find that the Spectral Energy Distributions (SEDs), {nu}S({nu}), of most of our blazars peak at {nu}SEDp<105GHz; the median peak wavelength is {lambda}SEDp=~93{mu}m. Only six have {nu}SEDp>105GHz.
- ID:
- ivo://CDS.VizieR/J/ApJ/794/152
- Title:
- PACS observations of Herschel-BAT sample
- Short Name:
- J/ApJ/794/152
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Far-Infrared (FIR) photometry from the Photodetector Array Camera and Spectrometer on the Herschel Space Observatory is presented for 313 nearby, hard X-ray selected galaxies from the 58 month Swift Burst Alert Telescope (BAT) Active Galactic Nuclei catalog. The present data do not distinguish between the FIR luminosity distributions at 70 and 160{mu}m for Seyfert 1 and Seyfert 2 galaxies. This result suggests that if the FIR emission is from the nuclear obscuring material surrounding the accretion disk, then it emits isotropically, independent of orientation. Alternatively, a significant fraction of the 70 and 160{mu}m luminosity could be from star formation, independent of active galactic nucleus (AGN) type. Using a non-parametric test for partial correlation with censored data, we find a statistically significant correlation between the AGN intrinsic power (in the 14-195keV band) and the FIR emission at 70 and 160{mu}m for Seyfert 1 galaxies. We find no correlation between the 14-195keV and FIR luminosities in Seyfert 2 galaxies. The observed correlations suggest two possible scenarios: (1) if we assume that the FIR luminosity is a good tracer of star formation, then there is a connection between star formation and the AGN at sub-kiloparsec scales, or (2) dust heated by the AGN has a statistically significant contribution to the FIR emission. Using a Spearman rank-order analysis, the 14-195keV luminosities for the Seyfert 1 and 2 galaxies are weakly statistically correlated with the F_70_/F_160_ratios.
