- ID:
- ivo://CDS.VizieR/J/ApJ/685/958
- Title:
- Spitzer and Chandra sources in galactic center
- Short Name:
- J/ApJ/685/958
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have studied the correlation between 2357 Chandra X-ray point sources in a 40x40pc field and ~20000 infrared sources we observed in the corresponding subset of our 2x1.4{deg} Spitzer/IRAC Galactic Center Survey at 3.6-8.0um, using various spatial and X-ray hardness thresholds. The correlation was determined for source separations of less than 0.5", 1", or 2". Only the soft X-ray sources show any correlation with infrared point sources on these scales, and that correlation is very weak. The upper limit on hard X-ray sources that have infrared counterparts is <1.7% (3{sigma}). However, because of the confusion limit of the IR catalog, we only detect IR sources with absolute magnitudes <~1. As a result, a stronger correlation with fainter sources cannot be ruled out. Only one compact IR source, IRS 13, coincides with any of the dozen prominent X-ray emission features in the 3x3pc region centered on Sgr A*, and the diffuse X-ray and IR emission around Sgr A* seems to be anticorrelated on a few-arcsecond scale. We compare our results with previous identifications of near-infrared companions to Chandra X-ray sources.
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- ID:
- ivo://CDS.VizieR/J/AJ/131/250
- Title:
- Spitzer 70 and 160um observations in xFLS
- Short Name:
- J/AJ/131/250
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 70 and 160{mu}m observations from the Spitzer extragalactic First Look Survey (xFLS). The data reduction techniques and the methods for producing co-added mosaics and source catalogs are discussed. Currently, 26% of the 70{mu}m sample and 49% of the 160{mu}m-selected sources have redshifts. The majority of sources with redshifts are star-forming galaxies at z<0.5, while about 5% have infrared colors consistent with active galactic nuclei. The observed infrared colors agree with the spectral energy distributions (SEDs) of local galaxies previously determined from IRAS and Infrared Space Observatory data.
- ID:
- ivo://CDS.VizieR/J/ApJS/218/33
- Title:
- Spitzer-CANDELS catalog within 5 deep fields
- Short Name:
- J/ApJS/218/33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Spitzer-Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (S-CANDELS; PI G.Fazio) is a Cycle 8 Exploration Program designed to detect galaxies at very high redshifts (z>5). To mitigate the effects of cosmic variance and also to take advantage of deep coextensive coverage in multiple bands by the Hubble Space Telescope (HST) Multi-cycle Treasury Program CANDELS, S-CANDELS was carried out within five widely separated extragalactic fields: the UKIDSS Ultra-deep Survey, the Extended Chandra Deep Field South, COSMOS, the HST Deep Field North, and the Extended Groth Strip. S-CANDELS builds upon the existing coverage of these fields from the Spitzer Extended Deep Survey (SEDS), a Cycle 6 Exploration Program, by increasing the integration time from SEDS' 12hr to a total of 50hr but within a smaller area, 0.16deg^2^. The additional depth significantly increases the survey completeness at faint magnitudes. This paper describes the S-CANDELS survey design, processing, and publicly available data products. We present Infrared Array Camera (IRAC) dual-band 3.6+4.5{mu}m catalogs reaching to a depth of 26.5 AB mag. Deep IRAC counts for the roughly 135000 galaxies detected by S-CANDELS are consistent with models based on known galaxy populations. The increase in depth beyond earlier Spitzer/IRAC surveys does not reveal a significant additional contribution from discrete sources to the diffuse Cosmic Infrared Background (CIB). Thus it remains true that only roughly half of the estimated CIB flux from COBE/DIRBE is resolved.
- ID:
- ivo://CDS.VizieR/J/ApJS/244/30
- Title:
- Spitzer catalog of Herschel star-forming galaxies
- Short Name:
- J/ApJS/244/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The largest Herschel extragalactic surveys, H-ATLAS and HerMES, have selected a sample of "ultrared" dusty star-forming galaxies (DSFGs) with rising SPIRE flux densities (S_500_>S_350_>S_250_; the so-called "500{mu}m risers") as an efficient way for identifying DSFGs at higher redshift (z>4). In this paper, we present a large Spitzer follow-up program of 300 Herschel ultrared DSFGs. We have obtained high-resolution Atacama Large Millimeter/submillimeter Array, Northern Extended Millimeter Array, and SMA data for 63 of them, which allow us to securely identify the Spitzer/IRAC counterparts and classify them as gravitationally lensed or unlensed. Within the 63 ultrared sources with high-resolution data, ~65% appear to be unlensed and ~27% are resolved into multiple components. We focus on analyzing the unlensed sample by directly performing multiwavelength spectral energy distribution modeling to derive their physical properties and compare with the more numerous z~2 DSFG population. The ultrared sample has a median redshift of 3.3, stellar mass of 3.7x10^11^M_{sun}_, star formation rate (SFR) of 730M_{sun}_/yr, total dust luminosity of 9.0x10^12^L_{sun}_, dust mass of 2.8x10^9^M_{sun}_, and V-band extinction of 4.0, which are all higher than those of the ALESS DSFGs. Based on the space density, SFR density, and stellar mass density estimates, we conclude that our ultrared sample cannot account for the majority of the star-forming progenitors of the massive, quiescent galaxies found in infrared surveys. Our sample contains the rarer, intrinsically most dusty, luminous, and massive galaxies in the early universe that will help us understand the physical drivers of extreme star formation.
- ID:
- ivo://CDS.VizieR/J/ApJS/184/230
- Title:
- Spitzer high-resolution MIR spectral atlas
- Short Name:
- J/ApJS/184/230
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an atlas of Spitzer/IRS high-resolution (R~600) 10-37um spectra for 24 well known starburst galaxies. The spectra are dominated by fine-structure lines, molecular hydrogen lines, and emission bands of polycyclic aromatic hydrocarbons (PAHs). Six out of the eight objects with a known active galactic nucleus (AGN) component show emission of the high excitation [NeV] line. This line is also seen in one other object (NGC 4194) with, a priori, no known AGN component. In addition to strong PAH emission features in this wavelength range (11.3, 12.7, 16.4um), the spectra reveal other weak hydrocarbon features at 10.6, 13.5, 14.2um, and a previously unreported emission feature at 10.75um. An unidentified absorption feature at 13.7um is detected in many of the starbursts. We use the fine-structure lines to derive the abundance of neon and sulfur for 14 objects where the HI 7-6 line is detected. We further use the molecular hydrogen lines to sample the properties of the warm molecular gas. Several basic diagrams characterizing the properties of the sample are also shown. We have combined the spectra of all the pure starburst objects to create a high signal-to-noise ratio template, which is available to the community.
- ID:
- ivo://CDS.VizieR/J/ApJ/769/80
- Title:
- Spitzer/IRAC observations of five deep fields
- Short Name:
- J/ApJ/769/80
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Spitzer Extended Deep Survey (SEDS) is a very deep infrared survey within five well-known extragalactic science fields: the UKIDSS Ultra-Deep Survey, the Extended Chandra Deep Field South, COSMOS, the Hubble Deep Field North, and the Extended Groth Strip. SEDS covers a total area of 1.46deg^2^ to a depth of 26 AB mag (3{sigma}) in both of the warm Infrared Array Camera (IRAC) bands at 3.6 and 4.5{mu}m. Because of its uniform depth of coverage in so many widely-separated fields, SEDS is subject to roughly 25% smaller errors due to cosmic variance than a single-field survey of the same size. SEDS was designed to detect and characterize galaxies from intermediate to high redshifts (z=2-7) with a built-in means of assessing the impact of cosmic variance on the individual fields. Because the full SEDS depth was accumulated in at least three separate visits to each field, typically with six-month intervals between visits, SEDS also furnishes an opportunity to assess the infrared variability of faint objects. This paper describes the SEDS survey design, processing, and publicly-available data products. Deep IRAC counts for the more than 300000 galaxies detected by SEDS are consistent with models based on known galaxy populations. Discrete IRAC sources contribute 5.6+/-1.0 and 4.4+/-0.8nW/m2/sr at 3.6 and 4.5{mu}m to the diffuse cosmic infrared background (CIB). IRAC sources cannot contribute more than half of the total CIB flux estimated from DIRBE data. Barring an unexpected error in the DIRBE flux estimates, half the CIB flux must therefore come from a diffuse component.
- ID:
- ivo://CDS.VizieR/J/A+A/503/107
- Title:
- Spitzer/IRAC view of Sh2-284
- Short Name:
- J/A+A/503/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using Spitzer/IRAC observations of a region to be observed by the CoRoT satellite, we have unraveled a new complex star-forming region at low metallicity in the outer Galaxy. We perform a study of S284 in order to outline the chain of events in this star-forming region.
- ID:
- ivo://CDS.VizieR/J/A+A/626/A92
- Title:
- Spitzer/IRS analysis of the 30-micron sources
- Short Name:
- J/A+A/626/A92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis and comparison of the 30{mu}m dust features seen in the Spitzer Space Telescope spectra of 207 carbon-rich asymptotic giant branch (AGB) stars, post-AGB objects, and planetary nebulae (PNe) located in the Milky Way, the Magellanic Clouds (MCs), or the Sagittarius dwarf spheroidal galaxy (Sgr dSph), which are characterised by different average metallicities. We investigated whether the formation of the 30{mu}m feature carrier may be a function of the metallicity. Through this study we expect to better understand the late stages of stellar evolution of carbon-rich stars in these galaxies. Our analysis uses the "Manchester method" as a basis for estimating the temperature of dust for the carbon-rich AGB stars and the PNe in our sample. For post-AGB objects we changed the wavelength ranges used for temperature estimation, because of the presence of the 21{mu}m feature on the short wavelength edge of the 30{mu}m feature. We used a black-body function with a single temperature deduced from the Manchester method or its modification to approximate the continuum under the 30{mu}m feature. We find that the strength of the 30{mu}m feature increases until dust temperature drops below 400K. Below this temperature, the large loss of mass and probably the self-absorption effect reduces the strength of the feature. During the post-AGB phase, when the intense mass-loss has terminated, the optical depth of the circumstellar envelope is smaller, and the 30{um}m feature becomes visible again, showing variety of values for post-AGB objects and PNe, and being comparable with the strengths of AGB stars. In addition, the AGB stars and post-AGB objects show similar values of central wavelengths - usually between 28.5 and 29.5{mu}m. However, in case of PNe the shift of the central wavelength towards longer wavelengths is visible. The normalised median profiles for AGB stars look uniformly for various ranges of dust temperature, and different galaxies. We analysed the profiles of post-AGB objects and PNe only within one dust temperature range (below 200K), and they were also similar in different galaxies. In the spectra of 17 PNe and five post-AGB objects we found the broad 16-24{mu}m feature. Two objects among the PNe group are the new detections: SMP LMC 51, and SMP LMC 79, whereas in the case of post-AGBs the new detections are: IRAS 05370-7019, IRAS 05537-7015, and IRAS 21546+4721. In addition, in the spectra of nine PNe we found the new detections of 16-18{mu}m feature. We also find that the Galactic post-AGB object IRAS 11339-6004 has a 21{mu}m emission. Finally, we have produced online catalogues of photometric data and Spitzer IRS spectra for all objects that show the 30{mu}m feature. These resources are available online for use by the community. The most important conclusion of our work is the fact that the formation of the 30{mu}m feature is affected by metallicity. Specifically that, as opposed to more metal-poor samples of AGB stars in the MCs, the feature is seen at lower mass-loss rates, higher temperatures, and has seen to be more prominent in Galactic carbon stars. The averaged feature (profile) in the AGB, post-AGB objects, and PNe seems unaffected by metallicity at least between a fifth and solar metallicity, but in the case of PNe it is shifted to significantly longer wavelengths.
- ID:
- ivo://CDS.VizieR/J/ApJ/777/156
- Title:
- Spitzer/IRS spectra of GOALS luminous IR galaxies
- Short Name:
- J/ApJ/777/156
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the data and our analysis of mid-infrared atomic fine-structure emission lines detected in Spitzer/Infrared Spectrograph high-resolution spectra of 202 local Luminous Infrared Galaxies (LIRGs) observed as part of the Great Observatories All-sky LIRG Survey (GOALS). We readily detect emission lines of [SIV], [NeII], [NeV], [NeIII], [SIII]_18.7{mu}m_, [OIV], [FeII], [SIII]_33.5{mu}m_, and [SiII]. More than 75% of these galaxies are classified as starburst-dominated sources in the mid-infrared, based on the [NeV]/[NeII] line flux ratios and equivalent width of the 6.2{mu}m polycyclic aromatic hydrocarbon feature. We compare ratios of the emission-line fluxes to those predicted from stellar photo-ionization and shock-ionization models to constrain the physical and chemical properties of the gas in the starburst LIRG nuclei. Comparing the [SIV]/[NeII] and [NeIII]/[NeII] line ratios to the Starburst99-Mappings III models with an instantaneous burst history, the emission-line ratios suggest that the nuclear starbursts in our LIRGs have ages of 1-4.5 Myr, metallicities of 1-2Z_{sun}_, and ionization parameters of 2-8x10^7^cm/s. Based on the [SIII]_33.5{mu}m_/[SIII]_18.7{mu}m_ ratios, the electron density in LIRG nuclei is typically one to a few hundred/cm3, with a median electron density of ~300/cm3, for those sources above the low density limit for these lines.
- ID:
- ivo://CDS.VizieR/J/ApJ/709/1257
- Title:
- Spitzer-IRS spectra of Seyfert galaxies. II.
- Short Name:
- J/ApJ/709/1257
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present our Spitzer-Infrared Spectrometer (IRS) spectroscopic survey from 10um to 37um of the Seyfert galaxies of the 12um Galaxy Sample (12MSG), collected in a high-resolution mode (R~600). The new spectra of 61 galaxies, together with the data we already published, give us a total of 91 12um Seyfert galaxies observed, out of 112. We discuss the mid-IR emission lines and features of the Seyfert galaxies, using an improved active galactic nucleus (AGN) classification scheme: instead of adopting the usual classes of Seyfert 1's and Seyfert 2's, we use the spectropolarimetric data from the literature to divide the objects into categories "AGN 1" and "AGN 2," where AGN 1's include all broad-line objects, including the Seyfert 2's showing hidden broad lines in polarized light. The remaining category, AGN 2's, contains only Seyferts with no detectable broad lines in either direct or polarized spectroscopy. We present various mid-IR observables, such as ionization-sensitive and density-sensitive line ratios, the polycyclic aromatic hydrocarbon (PAH) 11.25um feature and the H_2_S(1) rotational line equivalent widths (EWs), the (60-25um) spectral index, and the source extendedness at 19um, to characterize similarities and differences in the AGN populations, in terms of AGN dominance versus star formation dominance.