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3191. SED of Spitzer quasars (QUEST)
ID:
ivo://CDS.VizieR/J/ApJ/666/806
Title:
SED of Spitzer quasars (QUEST)
Short Name:
J/ApJ/666/806
Date:
21 Oct 2021
Publisher:
CDS
Description:
This is the second paper studying the QSOs in the Spitzer QUEST sample. Previously we presented new PAH measurements and argued that most of the observed far-infrared (FIR) radiation is due to star-forming activity. Here we present spectral energy distributions (SEDs) by supplementing our data with optical, NIR, and FIR observations. We define two subgroups, of "weak FIR" and "strong FIR" QSOs, and a third group of FIR nondetections. Assuming a starburst origin for the FIR, we obtain "intrinsic" active galactic nucleus (AGN) SEDs by subtracting a starburst template from the mean SEDs. The resulting SEDs are remarkably similar for all groups.
3192. SED-selected AGN in the VIPERS field
ID:
ivo://CDS.VizieR/J/MNRAS/495/1853
Title:
SED-selected AGN in the VIPERS field
Short Name:
J/MNRAS/495/1853
Date:
21 Oct 2021
Publisher:
CDS
Description:
The detection of X-ray emission constitutes a reliable and efficient tool for the selection of active galactic nuclei (AGNs), although it may be biased against the most heavily absorbed AGNs. Simple mid-infrared (IR) broad-band selection criteria identify a large number of luminous and absorbed AGNs, yet again host contamination could lead to non-uniform and incomplete samples. Spectral energy distribution (SED) decomposition is able to decouple the emission from the AGN versus that from star-forming regions, revealing weaker AGN components. We aim to identify the obscured AGN population in the VIMOS Public Extragalactic Redshift Survey in the Canada-France-Hawaii Telescope Legacy Survey W1 field through SED modelling. We construct SEDs for 6860 sources and identify 160 AGNs at a high confidence level using a Bayesian approach. Using optical spectroscopy, we confirm the nature of ~85 per cent of the AGNs. Our AGN sample is highly complete (~92 per cent) compared to mid-IR colour-selected AGNs, including a significant number of galaxy-dominated systems with lower luminosities. In addition to the lack of X-ray emission (80 per cent), the SED fitting results suggest that the majority of the sources are obscured. We use a number of diagnostic criteria in the optical, IR, and X-ray regimes to verify these results. Interestingly, only 35 per cent of the most luminous mid-IR-selected AGNs have X-ray counterparts suggesting strong absorption. Our work emphasizes the importance of using SED decomposition techniques to select a population of type II AGNs, which may remain undetected by either X-ray or IR colour surveys.
3193. SEDs in ADFS (AKARI Deep Field South)
ID:
ivo://CDS.VizieR/J/A+A/514/A11
Title:
SEDs in ADFS (AKARI Deep Field South)
Short Name:
J/A+A/514/A11
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate the nature and properties of far-infrared (FIR) sources in the AKARI Deep Field South (ADF-S). We performed an extensive search for the counterparts to 1000 ADF-S objects brighter than 0.0301Jy in the WIDE-S (90um) AKARI band in the public databases (NED and SIMBAD). We analyzed the properties of the resulting sample: statistics of the identified objects, quality of position determination of the ADF-S sources, their number counts, redshift distribution, and comparison of morphological types, when the corresponding information was available. We performed a simplified analysis of the clustering properties of the ADF-S sources and compiled spectral energy distributions (SEDs) of objects with the highest quality photometry, using three different models. Among 1000 investigated ADF-S sources, 545 were identified with sources at other wavelengths in public databases. From them, 518 are known galaxies and 343 of these were previously known as infra-red sources. Among the remaining sources, there are two quasars and both infrared and radio sources of unknown origin. Among six stellar identifications, at least five are probably the effect of contamination. We measured the redshifts of 48 extragalactic objects and determined the morphological types of 77 galaxies. We present SED models of 47 sources with sufficiently good photometric data. Conclusions: We conclude that the bright FIR point sources observed in the ADF-S are mostly nearby galaxies. Their properties are very similar to the properties of the local population of optically bright galaxies, except for unusually high ratio of peculiar or interacting objects and a lower percentage of elliptical galaxies. The percentage of lenticular galaxies is the same as in the optically bright population, which suggests that galaxies of this type may frequently contain a significant amount of cool dust. It is possible that source confusion plays a significant role in more than 34% of measurements. The SEDs correspond to a variety of galaxy types, from very actively star forming to very quiescent. The AKARI long wavelength bands data have enabled us to determine for the first time that these galaxies are objects with very cool dust.
3194. SEDs of ELAIS-S1 mid-IR sources
ID:
ivo://CDS.VizieR/J/ApJ/684/136
Title:
SEDs of ELAIS-S1 mid-IR sources
Short Name:
J/ApJ/684/136
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the broadband SEDs of the largest available highly complete (72%) spectroscopic sample of MIR-selected galaxies and AGNs at intermediate redshift. The sample contains 203 extragalactic sources from the 15um ELAIS-SWIRE survey, all with measured spectroscopic redshift. Most of these sources have full multiwavelength coverage from the FUV (GALEX) to the FIR (Spitzer) and lie in the redshift range 0.1<z<1.3. This large sample allows us for the first time to characterize the spectral properties of sources responsible for the strong evolution observed in the MIR. Based on SED-fitting, we have classified the MIR sources, identifying AGN signatures in about 50% of them. This fraction is significantly higher than that derived from optical spectroscopy (~29%) and is due in particular to the identification of AGN activity in objects spectroscopically classified as galaxies (the spectroscopic classification may be somewhat unreliable because of host galaxy dilution in the optical). It is likely that in most of our objects, the AGN is either obscured or low luminosity, and thus dominates the energetic output only in the MIR, showing up just in the range where the host galaxy SED has a minimum. The fraction of AGNs strongly depends on flux density, with that derived through the SED-fitting about 20% at S_15um_~0.5-1mJy and gradually increasing to 100% at S_15um_>10mJy, while that obtained from optical spectroscopy is never >30%, even at higher flux densities.
3195. SEDs of galaxies at 3.8<z<5 in GOODS
ID:
ivo://CDS.VizieR/J/ApJ/738/69
Title:
SEDs of galaxies at 3.8<z<5 in GOODS
Short Name:
J/ApJ/738/69
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present evidence for strong H{alpha} emission in galaxies with spectroscopic redshifts in the range of 3.8<z<5.0 over the Great Observatories Origins Deep Survey fields. Among 74 galaxies detected in the Spitzer IRAC 3.6 and 4.5um bands, more than 70% of the galaxies show clear excess at 3.6um compared to the expected flux density from stellar continuum only. We provide evidence that this 3.6um excess is due to H{alpha} emission redshifted into the 3.6um band, and classify these 3.6um excess galaxies to be H{alpha} emitter (HAE) candidates. The selection of HAE candidates using an excess in broadband filters is sensitive to objects whose rest-frame H{alpha} equivalent width (EW) is larger than 350{AA}. The H{alpha} inferred star formation rates (SFRs) of the HAEs range between 20 and 500M_{sun}_/yr and are a factor of ~6 larger than SFRs inferred from the UV continuum. The ratio between the H{alpha} luminosity and UV luminosity of HAEs is also on average larger than that of local starbursts.
3196. SEDs of galaxy cluster members
ID:
ivo://CDS.VizieR/J/ApJ/729/22
Title:
SEDs of galaxy cluster members
Short Name:
J/ApJ/729/22
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results from a study of AGNs and their host galaxies found in low-redshift galaxy clusters. We fit model spectral energy distributions (SEDs) to the combined visible and mid-infrared (MIR) photometry of cluster members and use these model SEDs to determine stellar masses and star formation rates (SFRs). We identify two populations of AGNs, the first based on their X-ray luminosities (X-ray AGNs) and the second based on the presence of a significant AGN component in their model SEDs (IR AGNs). We find that the two AGN populations are nearly disjoint; only 8 out of 44 AGNs are identified with both techniques.
3197. SEDs of M33 HII regions
ID:
ivo://CDS.VizieR/J/A+A/552/A140
Title:
SEDs of M33 HII regions
Short Name:
J/A+A/552/A140
Date:
21 Oct 2021
Publisher:
CDS
Description:
Within the framework of the Herschel M33 extended survey HerM33es and in combination with multi-wavelength data we study the spectral energy distribution (SED) of a set of HII regions in the Local Group galaxy M33 as a function of the morphology. We analyse the emission distribution in regions with different morphologies and present models to infer the H{alpha} emission measure observed for HII regions with well defined morphology. We present a catalogue of 119 HII regions morphologically classified: 9 filled, 47 mixed, 36 shell, and 27 clear shell HII regions. For each object we extracted the photometry at twelve available wavelength bands, covering a wide wavelength range from FUV-1516{AA} (GALEX) to IR-250um (Herschel), and we obtained the SED for each object. We also obtained emission line profiles in vertical and horizontal directions across the regions to study the location of the stellar, ionised gas, and dust components. We constructed a simple geometrical model for the clear shell regions, whose properties allowed us to infer the electron density of these regions.
3198. SEDs of the radio continuum from KINGFISHER
ID:
ivo://CDS.VizieR/J/ApJ/836/185
Title:
SEDs of the radio continuum from KINGFISHER
Short Name:
J/ApJ/836/185
Date:
21 Oct 2021
Publisher:
CDS
Description:
We study the spectral energy distribution (SED) of the radio continuum (RC) emission from the Key Insight in Nearby Galaxies Emitting in Radio (KINGFISHER) sample of nearby galaxies to understand the energetics and origin of this emission. Effelsberg multi-wavelength observations at 1.4, 4.8, 8.4, and 10.5GHz combined with archive data allow us, for the first time, to determine the mid-RC (1-10GHz, MRC) bolometric luminosities and further present calibration relations versus the monochromatic radio luminosities. The 1-10GHz radio SED is fitted using a Bayesian Markov Chain Monte Carlo technique leading to measurements for the nonthermal spectral index (S_{nu}_~{nu}^-{alpha}_nt_^) and the thermal fraction (f_th_) with mean values of {alpha}_nt_=0.97+/-0.16 (0.79+/-0.15 for the total spectral index) and f_th_=(10+/-9)% at 1.4GHz. The MRC luminosity changes over ~3 orders of magnitude in the sample, 4.3x10^2^L_{sun}_<MRC<3.9x10^5^L_{sun}_. The thermal emission is responsible for ~23% of the MRC on average. We also compare the extinction-corrected diagnostics of the star-formation rate (SFR) with the thermal and nonthermal radio tracers and derive the first star-formation calibration relations using the MRC radio luminosity. The nonthermal spectral index flattens with increasing SFR surface density, indicating the effect of the star-formation feedback on the cosmic-ray electron population in galaxies. Comparing the radio and IR SEDs, we find that the FIR-to-MRC ratio could decrease with SFR, due to the amplification of the magnetic fields in star-forming regions. This particularly implies a decrease in the ratio at high redshifts, where mostly luminous/star-forming galaxies are detected.
3199. Segue 3 photometric and kinematic data
ID:
ivo://CDS.VizieR/J/AJ/142/88
Title:
Segue 3 photometric and kinematic data
Short Name:
J/AJ/142/88
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate the kinematic and photometric properties of the Segue 3 Milky Way companion using Keck/DEIMOS spectroscopy and Magellan/IMACS g- and r-band imaging. Using maximum likelihood methods to analyze the photometry, we study the structure and stellar population of Segue 3. We find that the half-light radius of Segue 3 is 26"+/-5" (2.1+/-0.4pc, for a distance of 17kpc) and the absolute magnitude is a mere M_V_=0.0+/-0.8mag, making Segue 3 the least luminous old stellar system known.
3200. Selected ALESS submm galaxies radio properties
ID:
ivo://CDS.VizieR/J/MNRAS/442/577
Title:
Selected ALESS submm galaxies radio properties
Short Name:
J/MNRAS/442/577
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a study of the radio properties of 870 {mu}m-selected submillimetre galaxies (SMGs), observed at high resolution with Atacama Large Millimeter Array (ALMA) in the Extended Chandra Deep Field South. From our initial sample of 76 ALMA SMGs, we detect 52 SMGs at >3{sigma} significance in Karl G. Jansky Very Large Array 1400MHz imaging, of which 35 are also detected at >3{sigma} in new 610MHz Giant Metre-Wave Radio Telescope imaging. Within this sample of radio-detected SMGs, we measure a median radio spectral index {alpha}_{610}_^{1400}^=-0.79+/-0.06, (with inter-quartile range {alpha}=[-1.16,-0.56]) and investigate the far-infrared/radio correlation via the parameter q_IR_, the logarithmic ratio of the rest-frame 8-1000{mu}m flux and monochromatic radio flux. Our median q_IR_=2.56+/-0.05 (inter-quartile range q_IR_=[2.42,2.78]) is higher than that typically seen in single-dish 870{mu}m-selected sources (q_IR_~2.4), which may reflect the fact that our ALMA-based study is not biased to radio-bright counterparts, as previous samples were. Finally, we search for evidence that q_IR_ and {alpha} evolve with age in a codependent manner, as predicted by starburst models: the data populate the predicted region of parameter space, with the stellar mass tending to increase along tracks of q_IR_ versus {alpha} in the direction expected, providing the first observational evidence in support of these models.