- ID:
- ivo://CDS.VizieR/J/ApJ/805/31
- Title:
- IR-radio luminosities & surface densities of galaxies
- Short Name:
- J/ApJ/805/31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the global star formation law --the relation between gas and star formation (SF) rates-- in a sample of 181 local galaxies with infrared (IR) luminosities spanning almost five orders of magnitude (10^7.8^-10^12.3^L_{sun}_), which includes 115 normal spiral galaxies and 66 (ultra)luminous IR galaxies ((U)LIRGs, L_IR_>>10^11^L_{sun}_). We derive their atomic, molecular gas, and dense molecular gas masses using newly available HI, CO, and HCN data from the literature, and SF rates are determined both from total IR (8-1000um) and 1.4GHz radio continuum (RC) luminosities. In order to derive the disk-averaged surface densities of gas and SF rates, we have taken a novel approach and used high-resolution RC observations to measure the radio sizes for all 181 galaxies. In our sample, we find that the surface density of dense molecular gas (as traced by HCN) has the tightest correlation with that of SF rates ({Sigma}_SFR_), and is linear in log-log space (power-law slope of N=1.01+/-0.02) across the full galaxy sample. The correlation between surface densities of molecular gas ({Sigma}_H_2__, traced by CO) and {Sigma}_SFR_ is sensitive to the adopted value of the CO-to-H_2_ conversion factor ({alpha}_CO_) used to infer molecular gas masses from CO luminosities. For a fixed Galactic value of {alpha}_CO_, a power law index of 1.14+/-0.02 is found. If instead we adopt values for {alpha}_CO_ of 4.6 and 0.8 for disk galaxies and (U)LIRGs, respectively, we find the two galaxy populations separate into two distinct {Sigma}_SFR_ versus {Sigma}_H_2__ relations. Finally, applying a continuously varying {alpha}_CO_ to our sample, we recover a single {Sigma}_SFR_-{Sigma}_H_2__ relation with slope of 1.60+/-0.03. The {Sigma}_SFR_ is a steeper function of total gas {Sigma}_gas_ (molecular gas with atomic gas) than that of molecular gas {Sigma}_H_2__, and are tighter among low-luminosity galaxies. We find no correlation between global surface densities of SFRs and atomic gas (HI).
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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/ApJ/642/673
- Title:
- IR-selected obscured AGN candidates
- Short Name:
- J/ApJ/642/673
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the large multiwavelength data set in the Chandra/SWIRE Survey (0.6deg^2^ in the Lockman Hole), we show evidence for the existence of highly obscured (Compton-thick) AGNs, estimate a lower limit to their surface density, and characterize their multiwavelength properties. Two independent selection methods based on the X-ray and infrared spectral properties are presented. The two selected samples contain (1) five X-ray sources with hard X-ray spectra and column densities >~10^24^cm^-2^ and (2) 120 infrared sources with red and AGN-dominated infrared SEDs. We estimate a surface density of at least 25 Compton-thick AGNs deg^2^ detected in the infrared in the Chandra/SWIRE field, of which 40% show distinct AGN signatures in their optical/near-infrared SEDs, the remaining being dominated by the host galaxy emission. Only ~33% of all Compton-thick AGNs are detected in the X-rays at our depth [F(0.3-8keV)>10^-15^ergs/cm^2^/s]. We report the discovery of two sources in our sample of Compton-thick AGNs, SWIRE J104409.95+585224.8 (z=2.54) and SWIRE J104406.30+583954.1 (z=2.43), which are the most luminous Compton-thick AGNs at high z currently known. The properties of these two sources are discussed in detail with an analysis of their spectra, SEDs, luminosities, and black hole masses.
- ID:
- ivo://CDS.VizieR/II/288
- Title:
- IRSF Magellanic Clouds Point Source Catalog
- Short Name:
- II/288
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a near-infrared (JHKs) photometric catalog, including 14811185 point sources for a 40deg^2^ area of the Large Magellanic Cloud, 2769682 sources for an 11deg^2^ area of the Small Magellanic Cloud, and 434145 sources for a 4deg^2^ area of the Magellanic Bridge. The 10sigma limiting magnitudes are 18.8, 17.8, and 16.6mag at J, H, and Ks, respectively. The photometric and astrometric accuracies for bright sources are 0.03-0.04mag and 0.1arcsec, respectively. Based on the catalog, we also present (1) spatial distributions, (2) luminosity functions, (3) color-color diagrams, and (4) color-magnitude diagrams for point sources toward the Magellanic Clouds.
- ID:
- ivo://CDS.VizieR/J/MNRAS/481/4206
- Title:
- IRSF survey of variable stars in the SMC
- Short Name:
- J/MNRAS/481/4206
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A very long-term near-infrared variable star survey towards the Large and Small Magellanic Clouds (LMC and SMC) was carried out using the 1.4m InfraRed Survey Facility at the South African Astronomical Observatory. This project was initiated in 2000 December in the LMC, and in 2001 July in the SMC. Since then an area of 3deg^2^ along the bar in the LMC and an area of 1deg^2^ in the central part of the SMC have been repeatedly observed. This survey is ongoing, but results obtained with data taken until 2017 December are reported in this paper. Over more than 15yr we have observed the two survey areas more than one hundred times. This is the first survey that provides near-infrared time-series data with such a long time baseline and on such a large scale. This paper describes the observations in the SMC and publishes a point source photometric catalogue, a variable source catalogue, and time-series data.
- ID:
- ivo://CDS.VizieR/J/A+A/602/A28
- Title:
- IR signature of CMBH in nearby dwarf galaxies
- Short Name:
- J/A+A/602/A28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the possible presence of active galactic nuclei (AGN) in dwarf galaxies and other nearby galaxies to identify candidates for follow-up confirmation and dynamical mass measurements. We identify candidate active central massive black holes (CMBH) using their mid-infrared emission, verify their nature using existing catalogues and optical line emission diagnostics, and study the relationship between their mass and the mass of their host galaxy. We use the Wide-field Infrared Survey Explorer (WISE) All-Sky Release Source Catalog and examine the infrared colours of a sample of dwarf galaxies and other nearby galaxies in order to identify both unobscured and obscured candidate AGN by applying the infrared colour diagnostic. Stellar masses of galaxies are obtained using a combination of three independent methods. Black hole masses are estimated using the bolometric luminosity of the AGN candidates and computed for three cases of the bolometric-to-Eddington luminosity ratio. We identify 303 candidate AGN, of which 276 were subsequently found to have been independently identified as AGN via other methods. The remaining 9% require follow-up observations for confirmation. The activity is detected in galaxies with stellar masses from ~10^6^ to 10^9^M_{sun}_; assuming the candidates are AGN, the black hole masses are estimated to be ~10^3^-10^6^M_{sun}_, adopting L_bol_=0.1L_Edd_. The black hole masses probed are several orders of magnitude smaller than previously reported for centrally located massive black holes. We examine the stellar mass versus black hole mass relationship in this low galaxy mass regime. We find that it is consistent with the existing relation extending linearly (in log-log space) into the lower mass regime. These findings suggest that CMBH are present in low-mass galaxies and in the Local Universe, and provide new impetus for follow-up dynamical studies of quiescent black holes in local dwarf galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/548/A29
- Title:
- IR source catalog of AKARI NEP-Wide field
- Short Name:
- J/A+A/548/A29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The InfraRed Camera (IRC) onboard AKARI has a comprehensive wavelength coverage with 9 photometric bands at 2-24 micron. Based on the NEP-Wide survey of AKARI (which covered a 5.4 sq.deg circular area centered on the NEP), we constructed a catalog for the infrared sources found in the survey area. Here we present the catalog containing about 114,800 sources detected at the nine IRC filter bands. This is a band-merged catalogue including all of the photometry results from the supplementary optical data as well as the IRC bands. To validate a source at a given IRC band, we searched counterparts in the other bands. The band-merging was done based on this cross-matching of the sources among the filter bands. If there is no detection in a certain band, we assigned the 99.000. The NIR sources having no counterpart in any other bands are finally excluded to avoid the false objects. See the reference for the details of the NEP-Wide survey and data reduction.
- ID:
- ivo://CDS.VizieR/II/181
- Title:
- IR sources in Magellanic Clouds
- Short Name:
- II/181
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The authors have used the IRAS data to construct maps of the Magellanic Clouds at wavelengths of 12, 25, 60, and 100 microns. These are contained in the published volume only. The position and characteristics of each source are included in this compilation. Also included are cross references to sources at other wavelengths (H-alpha emission nebulae, dark clouds, and stars) when these could be reasonably identified with the IR sources. IRAS IDs and the DPM field are also given.
- ID:
- ivo://CDS.VizieR/J/ApJ/640/768
- Title:
- IR sources in the NGC 5291 system
- Short Name:
- J/ApJ/640/768
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We observed two faint tidal dwarf galaxies (TDGs), NGC 5291 N and NGC 5291 S, with the Infrared Spectrograph on the Spitzer Space Telescope. We detect strong polycyclic aromatic hydrocarbon (PAH) emission at 6.2, 7.7, 8.6, 11.3, 12.6, and 16.5{mu}m, which match models of groups of 100 carbon atoms with an equal mixture of neutral and ionized PAHs.
- ID:
- ivo://CDS.VizieR/J/ApJS/207/37
- Title:
- IR sources spectroscopy in the AKARI NEP
- Short Name:
- J/ApJS/207/37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present spectra of 1796 sources selected in the AKARI North Ecliptic Pole Wide Survey field, obtained with MMT/Hectospec and WIYN/Hydra, for which we measure 1645 redshifts. We complemented the generic flux-limited spectroscopic surveys at 11 {mu}m and 15 {mu}m, with additional sources selected based on the MIR and optical colors. In MMT/Hectospec observations, the redshift identification rates are ~80% for objects with R < 21.5 mag. On the other hand, in WIYN/Hydra observations, the redshift identification rates are ~80% at R magnitudes brighter than 19 mag. The observed spectra were classified through the visual inspection or from the line diagnostics. We identified 1128 star-forming or absorption-line-dominated galaxies, 198 Type-1 active galactic nuclei (AGNs), 8 Type-2 AGNs, 121 Galactic stars, and 190 spectra in unknown category due to low signal-to-noise ratio. The spectra were flux-calibrated but to an accuracy of 0.1-0.18dex for most of the targets and worse for the remainder. We derive star formation rates (SFRs) from the mid-infrared fluxes or from the optical emission lines, showing that our sample spans an SFR range of 0.1 to a few hundred M_{sun}_/yr. We find that the extinction inferred from the difference between the IR and optical SFR increases as the IR luminosity increases but with a large scatter.