- ID:
- ivo://CDS.VizieR/J/AJ/146/151
- Title:
- Morphology catalog of nearby galaxies from SDSS DR7
- Short Name:
- J/AJ/146/151
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the statistical properties of a volume-limited sample of 7429 nearby (z=0.033-0.044) galaxies from the Sloan Digital Sky Survey Data Release 7. Our database includes morphology distribution as well as the structural and spectroscopic properties of each morphology type based on the recent remeasurements of spectral line strengths by Oh and collaborators. Our database does not include galaxies that are apparently smaller and flatter because morphology classification of them turned out to be difficult. Our statistics confirmed the up-to-date knowledge of galaxy populations, e.g., correlations between morphology and line strengths as well as the derived ages. We hope that this database will be useful as a reference.
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- ID:
- ivo://CDS.VizieR/J/MNRAS/419/687
- Title:
- Morphology of luminous radio-loud AGN
- Short Name:
- J/MNRAS/419/687
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a comparison between the optical morphologies of a complete sample of 46 southern 2Jy radio galaxies at intermediate redshifts (0.05<z<0.7) and those of two control samples of quiescent early-type galaxies: 55 ellipticals at redshifts z<=0.01 from the Observations of Bright Ellipticals at Yale (OBEY) survey, and 107 early-type galaxies at redshifts 0.2<z<0.7 in the Extended Groth Strip (EGS). Based on these comparisons, we discuss the role of galaxy interactions in the triggering of powerful radio galaxies (PRGs). We find that a significant fraction of quiescent ellipticals at low and intermediate redshifts show evidence for disturbed morphologies at relatively high surface brightness levels, which are likely the result of past or on-going galaxy interactions. However, the morphological features detected in the galaxy hosts of the PRGs (e.g. tidal tails, shells, bridges, etc.) are up to 2mag brighter than those present in their quiescent counterparts. Indeed, if we consider the same surface brightness limits, the fraction of disturbed morphologies is considerably smaller in the quiescent population (53% at z<0.2 and 48% at 0.2<=z<0.7) than in the PRGs (93% at z<0.2 and 95% at 0.2<=z<0.7 considering strong-line radio galaxies only). This supports a scenario in which PRGs represent a fleeting active phase of a subset of the elliptical galaxies that have recently undergone mergers/interactions. However, we demonstrate that only a small proportion (<~20%) of disturbed early-type galaxies are capable of hosting powerful radio sources.
- ID:
- ivo://CDS.VizieR/J/ApJ/698/1682
- Title:
- Most luminous dusty galaxies
- Short Name:
- J/ApJ/698/1682
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A summary of mid-infrared continuum luminosities arising from dust is given for very luminous galaxies, L_IR_>10^12^L_{sun}_, with 0.005<z<3.2 containing active galactic nuclei (AGNs), including 115 obscured AGNs and 60 unobscured (type 1) AGNs. All sources have been observed with the Spitzer Infrared Spectrograph. Obscured AGNs are defined as having optical depth {tau}>0.7 in the 9.7um silicate absorption feature (i.e., half of the continuum is absorbed) and having equivalent width of the 6.2um polycyclic aromatic hydrocarbon feature <0.1um (to avoid sources with a significant starburst component). Unobscured AGNs are defined as those that show silicate in emission. Luminosity {nu}L_{nu}_(8um) for the most luminous obscured AGNs is found to scale as (1+z)^2.6^ to z=2.8. For unobscured AGNs, the scaling with redshift is similar, but luminosities {nu}L_{nu}_(8um) are approximately three times greater for the most luminous sources. Using both obscured and unobscured AGNs having total infrared fluxes from the Infrared Astronomical Satellite, empirical relations are found between {nu}L_{nu}_(8um) and L_IR_.
- ID:
- ivo://CDS.VizieR/J/MNRAS/344/283
- Title:
- 100-Mpc-scale structures of radio galaxies
- Short Name:
- J/MNRAS/344/283
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present unequivocal evidence for a huge (~80x100x100Mp^3^) superstructure at redshift z=0.27 in the three-dimensional distribution of radio galaxies from the Texas-Oxford NVSS Structure 08h region (TONS08) sample, confirming tentative evidence for such a structure from the 7C redshift survey (7CRS). A second, newly discovered superstructure is also found less securely at redshift 0.35 (of dimensions ~100x100x100Mpc^3^). We present full observational details on the TONS08 sample which was constructed to probe structures in the redshift range 0<z<0.5 by matching NVSS sources with objects in APM catalogues to obtain a sample of optically bright (E~R<=19.83), radio-faint (1.4GHz flux density S_1.4_>=3mJy) radio galaxies in the same 25deg^2^ area as part II of the 7CRS.
- ID:
- ivo://CDS.VizieR/J/ApJS/38/351
- Title:
- M31 planetary nebulae
- Short Name:
- J/ApJS/38/351
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Finding charts and equatorial coordinates are presented for 311 planetary nebulae and for nearby reference stars in the Andromeda galaxy (M31). The standard deviation of the coordinates relative to the AGK3 is smaller than 1.0". The standard deviation of the coordinates relative to the reference stars is smaller than 0.5".
- ID:
- ivo://CDS.VizieR/J/ApJ/775/92
- Title:
- MQS III: AGNs behind LMC and SMC
- Short Name:
- J/ApJ/775/92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Magellanic Quasars Survey (MQS) has now increased the number of quasars known behind the Magellanic Clouds by almost an order of magnitude. All survey fields in the Large Magellanic Cloud (LMC) and 70% of those in the Small Magellanic Cloud (SMC) have been observed. The targets were selected from the third phase of the Optical Gravitational Lensing Experiment (OGLE-III) based on their optical variability, mid-IR, and/or X-ray properties. We spectroscopically confirmed 758 quasars (565 in the LMC and 193 in the SMC) behind the clouds, of which 94% (527 in the LMC and 186 in the SMC) are newly identified. The MQS quasars have long-term (12yr and growing for OGLE), high-cadence light curves, enabling unprecedented variability studies of quasars. The MQS quasars also provide a dense reference grid for measuring both the internal and bulk proper motions of the clouds, and 50 quasars are bright enough (I<~18mag) for absorption studies of the interstellar/intergalactic medium of the clouds.
507. Mrk421 in March 2010
- ID:
- ivo://CDS.VizieR/J/A+A/578/A22
- Title:
- Mrk421 in March 2010
- Short Name:
- J/A+A/578/A22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A flare from the TeV blazar Mrk 421, occurring in March 2010, was observed for 13 consecutive days from radio to very high energy (VHE; E>100GeV) gamma-rays with MAGIC, VERITAS, Whipple, FermiLAT, MAXI, RXTE, Swift, GASP-WEBT, and several optical and radio telescopes. We model the day-scale SEDs with one-zone and two-zone synchrotron self-Compton (SSC) models, investigate the physical parameters, and evaluate whether the observed broadband SED variability can be associated to variations in the relativistic particle population. Flux variability was remarkable in the X-ray and VHE bands while it was minor or not significant in the other bands. The one-zone SSC model can describe reasonably well the SED of each day for the 13 consecutive days. This flaring activity is also very well described by a two-zone SSC model, where one zone is responsible for the quiescent emission while the other smaller zone, which is spatially separated from the first one, contributes to the daily-variable emission occurring in X-rays and VHE gamma-rays. Both the one-zone SSC and the two-zone SSC models can describe the daily SEDs via the variation of only four or five model parameters, under the hypothesis that the variability is associated mostly to the underlying particle population. This shows that the particle acceleration and cooling mechanism producing the radiating particles could be the main one responsible for the broadband SED variations during the flaring episodes in blazars. The two-zone SSC model provides a better agreement to the observed SED at the narrow peaks of the low- and high-energy bumps during the highest activity, although the reported one-zone SSC model could be further improved by the variation of the parameters related to the emitting region itself ({delta}, B and R), in addition to the parameters related to the particle population.
- ID:
- ivo://CDS.VizieR/J/A+A/655/A89
- Title:
- Mrk421 multi-instrument observations in 2017
- Short Name:
- J/A+A/655/A89
- Date:
- 21 Mar 2022 08:46:33
- Publisher:
- CDS
- Description:
- We present a detailed characterisation and theoretical interpretation of the broadband emission of the paradigmatic TeV blazar Mrk 421, with a special focus on the multi-band flux correlations. The dataset has been collected through an extensive multi-wavelength campaign organised between 2016 December and 2017 June. The instruments involved are MAGIC, FACT, Fermi-LAT, Swift, GASP-WEBT, OVRO, Medicina, and Metsahovi. Additionally, four deep exposures (several hours long) with simultaneous MAGIC and NuSTAR observations allowed a precise measurement of the falling segments of the two spectral components. The very-high-energy (VHE; E>100GeV) gamma rays and X-rays are positively correlated at zero time lag, but the strength and characteristics of the correlation change substantially across the various energy bands probed. The VHE versus X-ray fluxes follow different patterns, partly due to substantial changes in the Compton dominance for a few days without a simultaneous increase in the X-ray flux (i.e. orphan gamma-ray activity). Studying the broadband spectral energy distribution (SED) during the days including NuSTAR observations, we show that these changes can be explained within a one-zone leptonic model with a blob that increases its size over time. The peak frequency of the synchrotron bump varies by two orders of magnitude throughout the campaign. Our multi-band correlation study also hints at an anti-correlation between UV-optical and X-ray at a significance higher than 3{sigma}. A VHE flare observed on MJD~57788 (2017 February 4) shows gamma-ray variability on multi-hour timescales, with a factor ten increase in the TeV flux but only a moderate increase in the keV flux. The related broadband SED is better described by a two-zone leptonic scenario rather than by a one-zone scenario. We find that the flare can be produced by the appearance of a compact second blob populated by high energetic electrons spanning a narrow range of Lorentz factors, from {gamma}'_min_=2x10^4^ to {gamma}'_max_=6x10^5^.
509. Mrk 926 spectra
- ID:
- ivo://CDS.VizieR/J/A+A/657/A122
- Title:
- Mrk 926 spectra
- Short Name:
- J/A+A/657/A122
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Mrk926 is known to be a highly-variable AGN. Furthermore, it is known to show very broad-line profiles. We intended to study the continuum and line profile variations of this object with high temporal resolution in order to determine its broad-line region (BLR) structure, and to derive its black hole (BH) mass. We carried out a high-cadence spectroscopic variability campaign of Mrk926 with the 10m HET telescope, aided by photometric V-band data taken with the C18 telescope at the Wise Observatory, over a period of about five months. We extracted spectroscopic continuum and line light curves, and computed cross-correlation functions (CCFs) as well as velocity-resolved CCFs with respect to the combined spectroscopic and photometric V-band light curve. The continuum luminosity of Mrk926 showed a drastic decrease during our campaign. The luminosity dropped to less than 50% of its original luminosity within 2.5 months only. Furthermore, the spectra of Mrk926 show complex and very broad Balmer line profiles including outer Balmer satellites ranging from +/-5000 to +/-13000km/s. The integrated H{alpha}, H{beta} and HeI_5876_ line light curves are delayed relative to the continuum light curve. The Ha and Hb lines show two velocity-delay structures in the central part of their line profile (within +/-5000km/s) at ~10 and ~57 light-days, and at ~5 and ~48 light-days, respectively. These structures might be interpreted as the upper and lower half of an ellipse in the velocity-delay plane, that might be the signature of a line-emitting ring, inclined by ~50{deg} to the line of sight, orbiting the black hole at radii R of 33.5 and 26.5 light-days. We determined continuum luminosities log({lambda}*L_({lambda})_/erg/s) of 43.68 to 44.13 which are in good agreement with the established R_(BLR)-L_(AGN) relation. Adopting delays of 33.5 and 26.5 days for Ha and Hb, respectively, we derive a black hole mass of 1.1+/-0.2*10^8^M_{sun}_ which indicates a low Eddington ratio decreasing from 8 to 3 percent during our campaign. The Balmer satellite components show a higher correlation coefficient with respect to the continuum than the central line profile, and their response to the continuum variations is of the order of only 3-5 days. We attribute this to the central line segment and the Balmer satellites having different, spatially distinct regions of origin.
- ID:
- ivo://CDS.VizieR/J/ApJ/758/129
- Title:
- 4Ms Chandra Deep Field South 6-8keV galaxies
- Short Name:
- J/ApJ/758/129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the 4Ms Chandra Deep Field-South (CDF-S) survey, we have identified a sample of 6845 X-ray-undetected galaxies that dominates the unresolved {approx}20%-25% of the 6-8keV cosmic X-ray background (XRB). This sample was constructed by applying mass and color cuts to sources from a parent catalog based on GOODS-South Hubble Space Telescope z-band imaging of the central 6' radius area of the 4Ms CDF-S. The stacked 6-8keV detection is significant at the 3.9{sigma} level, but the stacked emission was not detected in the 4-6keV band, which indicates the existence of an underlying population of highly obscured active galactic nuclei (AGNs). Further examinations of these 6845 galaxies indicate that the galaxies on the top of the blue cloud and with redshifts of 1<~z<~3, magnitudes of 25<~z_850_<~28, and stellar masses of 2x10^8^<~M_{sstarf}_/M_{sun}_<~2x10^9^ make the majority contributions to the unresolved 6-8keV XRB. Such a population is seemingly surprising given that the majority of the X-ray-detected AGNs reside in massive (>~10^10^M_{sun}_) galaxies. We discuss constraints upon this underlying AGN population, supporting evidence for relatively low mass galaxies hosting highly obscured AGNs, and prospects for further boosting the stacked signal.
