- ID:
- ivo://CDS.VizieR/J/AJ/144/11
- Title:
- IR imaging, nuclear SEDs, Spitzer spectra of 22 AGNs
- Short Name:
- J/AJ/144/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-resolution mid-infrared (MIR) imaging, nuclear spectral energy distributions (SEDs), and archival Spitzer spectra for 22 low-luminosity active galactic nuclei (LLAGNs; L_bol_<~10^42^erg/s). Infrared (IR) observations may advance our understanding of the accretion flows in LLAGNs, the fate of the obscuring torus at low accretion rates, and, perhaps, the star formation histories of these objects. However, while comprehensively studied in higher-luminosity Seyferts and quasars, the nuclear IR properties of LLAGNs have not yet been well determined. We separate the present LLAGN sample into three categories depending on their Eddington ratio and radio emission, finding different IR characteristics for each class. (1) At the low-luminosity, low-Eddington-ratio (log L_bol_/L_Edd_< -4.6) end of the sample, we identify "host-dominated" galaxies with strong polycyclic aromatic hydrocarbon bands that may indicate active (circum-)nuclear star formation. (2) Some very radio-loud objects are also present at these low Eddington ratios. The IR emission in these nuclei is dominated by synchrotron radiation, and some are likely to be unobscured type 2 AGNs that genuinely lack a broad-line region. (3) At higher Eddington ratios, strong, compact nuclear sources are visible in the MIR images. The nuclear SEDs of these galaxies are diverse; some resemble typical Seyfert nuclei, while others lack a well-defined MIR "dust bump." Strong silicate emission is present in many of these objects. We speculate that this, together with high ratios of silicate strength to hydrogen column density, could suggest optically thin dust and low dust-to-gas ratios, in accordance with model predictions that LLAGNs do not host a Seyfert-like obscuring torus. We anticipate that detailed modeling of the new data and SEDs in terms of accretion disk, jet, radiatively inefficient accretion flow, and torus components will provide further insights into the nuclear structures and processes of LLAGNs.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/757/13
- Title:
- IR SEDs of 24um z~0.3-3 galaxies
- Short Name:
- J/ApJ/757/13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we characterize the infrared spectral energy distributions (SEDs) of mid-IR-selected z~0.3-3.0 and L_IR_~10^11^-10^13^L_{sun}_ galaxies, and study how their SEDs differ from those of local and high-z analogs. Infrared SEDs depend both on the power source (AGN or star formation) and the dust distribution. Therefore, differences in the SEDs of high-z and local galaxies provide clues as to differences in their physical conditions. Our mid-IR flux-limited sample of 191 sources is unique in size, and spectral coverage, including Spitzer mid-IR spectroscopy. Here, we add Herschel photometry at 250{mu}m, 350{mu}m, and 500{mu}m, which allows us, through fitting an empirical SED model, to obtain accurate total IR luminosities, as well as constrain the relative contributions of AGNs and starbursts to those luminosities. Our sample includes three broad categories of SEDs: ~23% of the sources are AGNs (i.e., where the AGN contributes >50% of L_IR_), ~30% are starbursts where an AGN contributes <20% of L_IR_, and the mid-IR spectra are starburst-like (i.e., strong polycyclic aromatic hydrocarbon features); and the largest group (~47%) are composites which show both significant AGN and starburst activity. In summary, our results show that there is strong evolution in the SEDs between local and z~2 IR-luminous galaxies, as well as that there is a wide range of SEDs among high redshift IR-luminous sources. The publicly available SED templates we derive from our sample will be particularly useful for infrared population synthesis models, as well as in the interpretation of other mid-IR high-z galaxies, in particular those detected by the recent all sky Wide-field Infrared Survey Explorer.
- ID:
- ivo://CDS.VizieR/J/A+A/576/A33
- Title:
- KINGFISH galaxy sample radial profile SED
- Short Name:
- J/A+A/576/A33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Physical conditions of the interstellar medium in galaxies are closely linked to the ambient radiation field and the heating of dust grains. In order to characterize dust properties in galaxies over a wide range of physical conditions, we present here the radial surface brightness profiles of the entire sample of 61 galaxies from Key Insights into Nearby Galaxies: Far-Infrared Survey with Herschel (KINGFISH). The main goal of our work is the characterization of the grain emissivities, dust temperatures, and interstellar radiation fields responsible for heating the dust. After fitting the dust and stellar radial profiles with exponential functions, we fit the far-infrared spectral energy distribution (SED) in each annular region with single-temperature modified black bodies using both variable (MBBV) and fixed (MBBF) emissivity indices {beta}, as well as with physically motivated dust models. Results show that while most SED parameters decrease with radius, the emissivity index {beta} also decreases with radius in some galaxies, but in others is increasing, or rising in the inner regions and falling in the outer ones. Despite the fixed grain emissivity (average {beta}~2.1) of the physically-motivated models, they are well able to accommodate flat spectral slopes with {beta}<=1. We find that flatter slopes ({beta}<=1.5) are associated with cooler temperatures, contrary to what would be expected from the usual T_dust_-{beta} degeneracy. This trend is related to variations in Umin since {beta} and U_min_ are very closely linked over the entire range in U_min_ sampled by the KINGFISH galaxies: low U_min_ is associated with flat {beta}<=1. Both these results strongly suggest that the low apparent {beta} values (flat slopes) in MBBV fits are caused by temperature mixing along the line-of-sight, rather than by intrinsic variations in grain properties.
- ID:
- ivo://CDS.VizieR/J/A+A/631/A38
- Title:
- Local galaxies dust properties
- Short Name:
- J/A+A/631/A38
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derived the dust properties for 753 local galaxies and examine how these relate to some of their physical properties. We present the derived dust emission properties, including model spectral energy distribution (SEDs), star formation rates (SFRs) and stellar masses, as well as their relations. We modelled the global dust-SEDs for 753 galaxies, treated statistically as an ensemble within a hierarchical Bayesian dust-SED modelling approach, so as to derive their infrared (IR) emission properties. To create the observed dust-SEDs, we used a multi-wavelength set of observations, ranging from near-IR to far-IR-to-submillimeter wavelengths. The model-derived properties are the dust masses (Mdust), the average interstellar radiation field intensities (Uav), the mass fraction of very small dust grains ("QPAH" fraction), as well as their standard deviations. In addition, we used mid-IR observations to derive SFR and stellar masses, quantities independent of the dust-SED modelling. We derive distribution functions of the properties for the galaxy ensemble and as a function of galaxy type. The mean value of Mdust for the early-type galaxies (ETGs) is lower than that for the late-type and irregular galaxies (LTGs and Irs, respectively), despite ETGs and LTGs having stellar masses spanning across the whole range observed. The U_av_ and "QPAH" fraction show no difference among different galaxy types. When fixing Uav to the Galactic value, the derived "QPAH" fraction varies across the Galactic value (0.071). The specific SFR increases with galaxy type, while this is not the case for the dust-specific SFR (SFR/M_dust_), showing an almost constant star formation efficiency per galaxy type. The galaxy sample is characterised by a tight relationship between the dust mass and the stellar mass for the LTGs and Irs, while ETGs scatter around this relation and tend towards smaller dust masses. While the relation indicates that Mdust may fundamentally be linked to M*, metallicity and U_av_ are the second parameter driving the scatter, which we investigate in a forthcoming work. We used the extended Kennicutt-Schmidt (KS) law to estimate the gas mass and the gas-to-dust mass ratio (GDR). The gas mass derived from the extended KS law is on average ~20% higher than that derived from the KS law, and a large standard deviation indicates the importance of the average star formation present to regulate star formation and gas supply. The average GDR for the LTGs and Irs is 370, and including the ETGs gives an average of 550.
- ID:
- ivo://CDS.VizieR/J/MNRAS/474/5049
- Title:
- Low-frequency study of 3C 31 with LOFAR
- Short Name:
- J/MNRAS/474/5049
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a deep, low-frequency radio continuum study of the nearby Fanaroff-Riley class I (FR I) radio galaxy 3C 31 using a combination of LOw Frequency ARray (LOFAR; 30-85 and 115-178MHz), Very Large Array (VLA; 290-420MHz), Westerbork Synthesis Radio Telescope (WSRT; 609MHz) and Giant Metre Radio Telescope (GMRT; 615MHz) observations.
- ID:
- ivo://CDS.VizieR/J/MNRAS/404/1639
- Title:
- MILES base models & new line index system
- Short Name:
- J/MNRAS/404/1639
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present synthetic spectral energy distributions (SEDs) for single-age, single-metallicity stellar populations (SSPs) covering the full optical spectral range at moderately high resolution [full width at half-maximum (FWHM)=2.3{AA}]. These SEDs constitute our base models, as they combine scaled-solar isochrones with an empirical stellar spectral library [Medium resolution INT Library of Empirical Spectra (MILES)], which follows the chemical evolution pattern of the solar neighbourhood. The models rely as much as possible on empirical ingredients, not just on the stellar spectra, but also on extensive photometric libraries, which are used to determine the transformations from the theoretical parameters of the isochrones to observational quantities. The unprecedented stellar parameter coverage of the MILES stellar library allowed us to safely extend our optical SSP SED predictions from intermediate- to very-old-age regimes and the metallicity coverage of the SSPs from super-solar to [M/H]=-2.3. SSPs with such low metallicities are particularly useful for globular cluster studies. We have computed SSP SEDs for a suite of initial mass function shapes and slopes. We provide a quantitative analysis of the dependence of the synthesized SSP SEDs on the (in)complete coverage of the stellar parameter space in the input library that not only shows that our models are of higher quality than those of other works, but also in which range of SSP parameters our models are reliable.
- ID:
- ivo://CDS.VizieR/III/207
- Title:
- Moscow Spectrophotometric Catalog (MSC)
- Short Name:
- III/207
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalogue contains the energy distribution of 223 stars of different spectral type and luminosity classes in the range 5975-10825{AA} with the step 50A. The observations were made at the Crimean Station of the Sternberg Astronomical Institute during 1978-1990 using near-infrared spectrophotometer installed at the 48-cm and 60-cm Zeiss reflectors. Standards are {beta} Ari, {gamma} Ori, {beta} Tau, {alpha} Leo, {eta} UMa, {alpha} Lyr, {alpha} Aql and {alpha} Peg. Energy distribution data in the spectra of standard stars was taken according to Volosina, Glushneva and Shenavrin (1980AZh....57.1003V). Monochromatic fluxes are in erg/(cm^2^.s.cm). Zero flux is expressed as 0.E+00.
- ID:
- ivo://CDS.VizieR/J/A+A/623/A65
- Title:
- Multiphotometry of M31 outer halo globular clusters
- Short Name:
- J/A+A/623/A65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we present photometry of 53 globular clusters (GCs) in the M31 outer halo, including the GALEX FUV and NUV, SDSS ugriz, 15 intermediate-band filters of BATC, and 2MASS JHKs bands. By comparing the multicolour photometry with stellar population synthesis models, we determine the metallicities, ages, and masses for these GCs, aiming to probe the merging/accretion history of M31. We find no clear trend of metallicity and mass with the de-projected radius. The halo GCs with age younger than ~8Gyr are mostly located at the de-projected radii around 100kpc, but this may be due to a selection effect. We also find that the halo GCs have consistent metallicities with their spatially-associated substructures, which provides further evidence of the physical association between them. Both the disk and halo GCs in M31 show a bimodal luminosity distribution. However, we should emphasize that there are more faint halo GCs which are not being seen in the disk. There are more faint halo GCs than the disk ones, and these faint GCs constitute the fainter part in the luminosity function. The bimodal luminosity function of the halo GCs may reflect different origin or evolution environment in their original hosts. The M31 halo GCs includes one intermediate metallicity group (-1.5<[Fe/H]<-0.4) and one metal-poor group ([Fe/H]<-1.5), while the disk GCs have one metal-rich group more. There are considerable differences between the halo GCs in M31 and the Milky Way (MW). The total number of M31 GCs is approximately three times more numerous than that of the MW, however, M31 has about six times the number of halo GCs in the MW. Compared to M31 halo GCs, the Galactic halo ones are mostly metal-poor. Both the numerous halo GCs and the higher-metallicity component are suggestive of an active merger history of M31.
- ID:
- ivo://CDS.VizieR/J/MNRAS/471/770
- Title:
- Parameters and IR excesses of Gaia DR1 stars
- Short Name:
- J/MNRAS/471/770
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Effective temperatures and luminosities are calculated for 1,475,921 Tycho-2 and 107,145 Hipparcos stars, based on distances from Gaia Data Release 1. Parameters are derived by comparing multi-wavelength archival photometry to BT-Settl model atmospheres. The 1-sigma uncertainties for the Tycho-2 and Hipparcos stars are +/-137K and +/-125K in temperature and +/-35 per cent and +/-19 per cent in luminosity. The luminosity uncertainty is dominated by that of the Gaia parallax. Evidence for infrared excess between 4.6 and 25 microns is found for 4256 stars, of which 1883 are strong candidates. These include asymptotic giant branch (AGB) stars, Cepheids, Herbig Ae/Be stars, young stellar objects, and other sources. We briefly demonstrate the capabilities of this dataset by exploring local interstellar extinction, the onset of dust production in AGB stars, the age and metallicity gradients of the solar neighbourhood and structure within the Gould Belt. We close by discussing the potential impact of future Gaia data releases.
- ID:
- ivo://CDS.VizieR/J/A+A/449/143
- Title:
- Photometry of M31 globular cluster candidates
- Short Name:
- J/A+A/449/143
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents accurate spectral energy distributions (SEDs) of 16 M31 globular clusters (GCs) confirmed by spectroscopy and/or high spatial-resolution imaging, as well as 30 M31 globular cluster candidates detected by Mochejska et al., Cat. J/AcA/48/455 (1998). Most of these candidates have m_V_>18, deeper than previous searches, and these candidates have not yet been confirmed to be globular clusters. The SEDs of these clusters and candidates are obtained as part of the BATC Multicolor Survey of the Sky, in which the spectrophotometrically-calibrated CCD images of M31 in 13 intermediate-band filters from 4000 to 10000{AA} were observed. These filters are specifically designed to exclude most of the bright and variable night-sky emission lines including the OH forest. In comparison to the SEDs of true GCs, we find that some of the candidate objects are not GCs in M31. SED fits show that theoretical simple stellar population (SSP) models can fit the true GCs very well. We estimate the ages of these GCs by comparing with SSP models.
