- ID:
- ivo://CDS.VizieR/J/MNRAS/506/4781
- Title:
- HR-PYPOPSTAR model
- Short Name:
- J/MNRAS/506/4781
- Date:
- 06 Dec 2021 20:15:01
- Publisher:
- CDS
- Description:
- We present the HR-PYPOPSTAR model, which provides a complete set (in ages) of high-resolution (HR) spectral energy distributions of Single Stellar Populations. The model uses the most recent high-wavelength-resolution theoretical atmosphere libraries for main-sequence, post-AGB/planetary nebulae and Wolf-Rayet stars. The spectral energy distributions are given for more than a hundred ages ranging from 0.1Myr to 13.8Gyr, at four different values of the metallicity (Z = 0.004, 0.008, 0.019, and 0.05), considering four different IMFs. The wavelength range goes from 91 to 24000{AA} in linear steps {delta}{lambda}=0.1{AA}, giving a theoretical resolving power R_th,5000_~50000 at 5000{AA}. This is the main novelty of these spectra, unique for their age and wavelength ranges. The models include the ionizing stellar populations that are relevant at both young (massive hot stars) and old (planetary nebulae) ages. We have tested the results with some examples of HR spectra recently observed with MEGARA at GTC. We highlight the importance of wavelength resolution in reproducing and interpreting the observational data from the last and forthcoming generations of astronomical instruments operating at 8-10m class telescopes, with higher spectral resolution than their predecessors.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/555/A64
- Title:
- Identifying gaps in flaring Herbig Ae/Be disks
- Short Name:
- J/A+A/555/A64
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The evolution of protoplanetary disks towards mature planetary systems is expected to include the formation of 'gaps' in the disk possibly due to planet formation. We studied the disks of four key intermediate mass (Herbig Ae/Be) stars in order to understand the influence of gaps to their observational appearance. We investigate mid-infrared images and perform radiative transfer modeling to examine the radial distribution of dust and PAHs. Our solutions constrain the sizes of the gaps. For one particular object, HD 97048, this is the first detection of a disk gap. The large gaps deplete the entire population of silicate particles with temperatures suitable for prominent mid-infrared feature emission, while small carbonaceous grains and PAHs can still show prominent emission at mid-infrared wavelengths. The absence of silicate emission features is due to the presence of large gaps in the critical temperature regime. Our results suggest that many, if not all Herbig disks with weak or no silicate features in the spectrum are disks with large gaps and can be characterized as (pre-)transitional. We conclude that the evolution of Herbig stars follows two different paths. Competition between the timescales of inner versus outer disk evolution determine whether young protoplanetary disks evolve into transitional disks (due to planet formation in the inner disk) or into flat disks (due to the grain growth and dust settling in the outer disk).
- ID:
- ivo://CDS.VizieR/J/MNRAS/471/59
- Title:
- Intrinsic AGN SEDs in PG quasars
- Short Name:
- J/MNRAS/471/59
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new analysis of the Palomar-Green quasar sample based on Spitzer and Herschel observations. (i) Assuming polycyclic aromatic hydrocarbon (PAH)-based star formation luminosities (L_SF_) similar to Symeonidis et al. (S16, 2016MNRAS.459..257S), we find mean and median intrinsic active galactic nucleus (AGN) spectral energy distributions (SEDs). These, in the far-infrared (FIR), appear hotter and significantly less luminous than the S16 mean intrinsic AGN SED. The differences are mostly due to our normalization of the individual SED that properly accounts for a small number of very FIR-luminous quasars. Our median, PAH-based SED represents ~6 per cent increase on the 1-243{mu}m luminosity of the extended Mor & Netzer (EM12, 2012MNRAS.420..526M) torus SED, while S16 find a significantly larger difference. It requires large-scale dust with T~20-30K, which, if optically thin and heated by the AGN, would be outside the host galaxy. (ii) We also explore the black hole and stellar mass growths, using L_SF_ estimates from fitting Herschel/PACS observations after subtracting the EM12 torus contribution. We use rough estimates of stellar mass, based on scaling relations, to divide our sample into groups: on, below and above the star formation main sequence (SFMS). Objects on the SFMS show a strong correlation between star formation luminosity and AGN bolometric luminosity, with a logarithmic slope of ~0.7. Finally, we derive the relative duty cycles of this and another sample of very luminous AGN at z=2-3.5. Large differences in this quantity indicate different evolutionary pathways for these two populations characterized by significantly different black hole masses.
- ID:
- ivo://CDS.VizieR/J/ApJ/841/76
- Title:
- Intrinsic far-IR SED of luminous AGNs
- Short Name:
- J/ApJ/841/76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The range of currently proposed active galactic nucleus (AGN) far-infrared templates results in uncertainties in retrieving host galaxy information from infrared observations and also undermines constraints on the outer part of the AGN torus. We discuss how to test and reconcile these templates. Physically, the fraction of the intrinsic AGN IR-processed luminosity compared with that from the central engine should be consistent with the dust-covering factor. In addition, besides reproducing the composite spectral energy distributions (SEDs) of quasars, a correct AGN IR template combined with an accurate library of star-forming galaxy templates should be able to reproduce the IR properties of the host galaxies, such as the luminosity-dependent SED shapes and aromatic feature strengths. We develop tests based on these expected behaviors and find that the shape of the AGN intrinsic far-IR emission drops off rapidly starting at ~20{mu}m and can be matched by an Elvis+ (1994, J/ApJS/95/1)-like template with a minor modification. Despite the variations in the near- to mid-IR bands, AGNs in quasars and Seyfert galaxies have remarkably similar intrinsic far-IR SEDs at {lambda}~20-100{mu}m, suggesting a similar emission character of the outermost region of the circumnuclear torus. The variations of the intrinsic AGN IR SEDs among the type-1 quasar population can be explained by the changing relative strengths of four major dust components with similar characteristic temperatures, and there is evidence for compact AGN-heated dusty structures at sub-kiloparsec scales in the far-IR.
- 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.
- 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/ApJ/595/247
- Title:
- Line intensities in the planetary nebula NGC 5307
- Short Name:
- J/ApJ/595/247
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Echelle spectrophotometry of the planetary nebula NGC 5307 is presented. The data consist of Very Large Telescope Ultraviolet Visual Echelle Spectrograph observations in the 3100-10360{AA} range. Electron temperatures and densities have been determined using different line intensity ratios. We determine the H, He, C, and O abundances based on recombination lines; these abundances are almost independent of the temperature structure of the nebula. We also determine the N, O, Ne, S, Cl, and Ar abundances based on collisionally excited lines; the ratios of these abundances relative to that of H depend strongly on the temperature structure of the nebula.
- 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.
