- ID:
- ivo://CDS.VizieR/J/MNRAS/449/3191
- Title:
- IR photometry of nearby RLGs
- Short Name:
- J/MNRAS/449/3191
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- By combining the data of the Two Micron All Sky Survey, the Wide-Field Infrared Survey Explorer and the AKARI satellite, we study the infrared colour properties of a sample of 2712 nearby radio-luminous galaxies (RLGs). These RLGs are divided into radio-loud (RL) active galactic nuclei (AGNs), mainly occurring at redshifts of 0.05<z<0.3 and star-forming-dominated RLGs (SFGs), mainly occurring at redshifts of 0.01<z<0.15. RL AGNs and SFGs are separately distributed in the ([3.4]-[4.6])-([4.6]-[12]) two-colour diagram, in which the RL AGNs display a double-core distribution, and the SFGs display a single-core distribution. SFGs have a redder [4.6]-[12] colour than RL AGNs due to the significant contribution from the dust component of SFGs. We find simple criteria of mid-infrared (MIR) colour separation between RL AGNs and SFGs such that: 95 per cent of RL AGNs have [4.6]-[12]<3.0 and 94 per cent of SFGs have [4.6]-[12]>3.0. We also analyse the MIR colours of RL AGNs divided into low- and high-excitation radio galaxies (LERGs and HERGs, respectively). The ([3.4]-[4.6])-([4.6]-[12]) diagram clearly shows separate distributions of LERGs and HERGs and a region of overlap, which suggests that LERGs and HERGs have different MIR properties. LERGs are responsible for the double-core distribution of RL AGNs on the ([3.4]-[4.6])-([4.6]-[12]) diagram. In addition, we also suggest 90-140{mu}m band spectral index {alpha}(90, 140)<-1.4 as a criterion of selecting nearby active galaxies with non-thermal emissions at far-infrared wavelengths.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/624/L5
- Title:
- IR photometry of z~10 galaxies in NICMOS fields
- Short Name:
- J/ApJ/624/L5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use all available fields with deep NICMOS imaging to search for J_110_-dropouts (H_160,AB_<~28) at z~10. Our primary data set for this search is the two J_110_+H_160_ NICMOS fields taken in parallel with the Advanced Camera for Surveys (ACS) Hubble Ultra Deep Field (UDF). The 5{sigma} limiting magnitudes were ~28.6 in J_110_ and ~28.5 in H_160_ (0.6" apertures).
- ID:
- ivo://CDS.VizieR/J/ApJ/707/890
- Title:
- IR properties of E and S0 galaxies
- Short Name:
- J/ApJ/707/890
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the infrared properties of a large sample of early-type galaxies, comparing data from the Spitzer archive with Ks-band emission from the Two Micron All Sky Survey. While most representations of this data result in correlations with large scatter, we find a remarkably tight relation among colors formed by ratios of luminosities in Spitzer-Multiband Imaging Photometer bands (24, 70, and 160um) and the Ks band. Remarkably, this correlation among E and S0 galaxies follows that of nearby normal galaxies of all morphological types.
- 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).
- 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/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/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.
- ID:
- ivo://CDS.VizieR/J/ApJ/730/19
- Title:
- IR spectra and SEDs for starbursts and AGNs
- Short Name:
- J/ApJ/730/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present spectroscopic results for all galaxies observed with the Spitzer Infrared Spectrograph (IRS) that also have total infrared fluxes f_IR_ measured with the Infrared Astronomical Satellite (IRAS), also using AKARI photometry when available. Infrared luminosities and spectral energy distributions (SEDs) from 8um to 160um are compared to polycyclic aromatic hydrocarbon emission from starburst galaxies or mid-infrared dust continuum from active galactic nuclei (AGNs) at rest-frame wavelengths ~8um. A total of 301 spectra are analyzed for which IRS and IRAS include the same unresolved source, as measured by the ratio f_{nu}_(IRAS 25um)/f_{nu}_(IRS 25um). Sources have 0.004<z<0.34 and 42.5<logL_IR_<46.8(erg/s) and cover the full range of starburst galaxy and AGN classifications.
- ID:
- ivo://CDS.VizieR/J/A+A/623/A135
- Title:
- IR spectral of 4 Ae/Be Herbig stars
- Short Name:
- J/A+A/623/A135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the interstellar medium, carbon (nano-)grains are a major component of interstellar dust. This solid phase is more vulnerable to processing and destruction than its silicate counterpart. It exhibits a complex, size-dependent evolution that is due to interactions within different radiative and dynamical environments. Infrared signatures of these carbon nano-grains are seen in a large number of discs around Herbig HAeBe stars. We probe the composition and evolution of carbon nano-grains at the surface of (pre-)transitional proto-planetary discs around Herbig stars. We present spatially resolved infrared emission spectra obtained with the Nasmyth Adaptive Optics System (NAOS) Near-Infrared Imager and Spectrograph (CONICA) at the Very Large Telescope (VLT) in the 3-4 microns range with a spatial resolution of 0.1-arcsec, which allowed us to trace aromatic, olefinic, and aliphatic bands that are attributed to sub-nanometer hydrocarbon grains. We applied a Gaussian fitting to analyse the observed spectral signatures. Finally, we propose an interpretation in the framework of theThe Heterogeneous dust Evolution Model of Interstellar Solids (THEMIS). We show the presence of several spatially extended spectral features that are related to aromatic and aliphatic hydrocarbon material in discs around Herbig stars, from 10 to 50-100au, and even in inner gaps that are devoid of large grains. The correlation and constant intensity ratios between aliphatic and aromatic CH stretching bands suggests a common nature of the carriers. Given their expected high destruction rates through UV photons, our observations suggest that they are continuously replenished at the disc surfaces.