- ID:
- ivo://CDS.VizieR/J/MNRAS/446/3199
- Title:
- 24um fluxes of GOODS-S AGN
- Short Name:
- J/MNRAS/446/3199
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of galaxies showing mid-infrared variability in data taken in the deepest Spitzer/MIPS 24{mu}m surveys in the Great Observatory Origins Deep Survey South field. We divide the data set in epochs and subepochs to study the long-term (months-years) and the short-term (days) variability. We use a {chi}^2^-statistics method to select active galactic nucleus (AGN) candidates with a probability <=1% that the observed variability is due to statistical errors alone. We find 39 (1.7% of the parent sample) sources that show long-term variability and 55 (2.2% of the parent sample) showing short-term variability. That is, 0.03sources/arcmin^2^ for both, long-term and short-term variable sources. After removing the expected number of false positives inherent to the method, the estimated percentages are 1.0 and 1.4% of the parent sample for the long term and short term, respectively. We compare our candidates with AGN selected in the X-ray and radio bands, and AGN candidates selected by their IR emission. Approximately, 50% of the MIPS (Multiband Imaging Photometer for Spitzer) 24{mu}m variable sources would be identified as AGN with these other methods. Therefore, MIPS 24{mu}m variability is a new method to identify AGN candidates, possibly dust obscured and low-luminosity AGN, that might be missed by other methods. However, the contribution of the MIPS 24{mu}m variable identified AGN to the general AGN population is small (<=13%) in GOODS-South.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/693/370
- Title:
- 24um flux-limited sample of galaxies
- Short Name:
- J/ApJ/693/370
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The mid-infrared spectroscopic analysis of a flux-limited sample of galaxies with f_{nu}_(24um)>10mJy is presented. Sources observed are taken from the Spitzer First Look Survey (FLS) catalog and from the NOAO Deep Wide-Field Survey region in Bootes (NDWFS). The spectroscopic sample includes 60 of the 100 sources in these combined catalogs having f_{nu}_(24um)>10 mJy. New spectra from the Spitzer Infrared Spectrograph are presented for 25 FLS sources and for 11 Bootes active galactic nuclei (AGNs); these are combined with 24 Bootes starburst galaxies previously published to determine the distribution of mid-infrared spectral characteristics for the total 10mJy sample. Sources have 0.01<z<2.4 and 41.8<log{nu}L_{nu}_(15um)<46.2(ergs/s).
1133. 11.5um image of NGC 835
- ID:
- ivo://CDS.VizieR/J/A+A/587/A1
- Title:
- 11.5um image of NGC 835
- Short Name:
- J/A+A/587/A1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Obscured active galactic nuclei (AGNs) are thought to be very common in the Universe. Observations and surveys have shown that the number of sources increases for near galaxies and at the low-luminosity regime (the so-called LLAGNs). Furthermore, many AGNs show changes in their obscuration properties at X-rays that may suggest a configuration of clouds very close to the accretion disk. However, these variations could also be due to changes in the intrinsic continuum of the source. It is therefore important to study nearby AGN to better understand the locus and distribution of clouds in the neighbourhood of the nucleus. We aim to study the nuclear obscuration of LLAGN NGC 835 and its extended emission using mid-infrared observations. We present sub-arcsecond-resolution mid-infrared 11.5um imaging of the LLAGN galaxy NGC 835 obtained with the instrument CanariCam in the Gran Telescopio CANARIAS (GTC), archival Spitzer/IRS spectroscopy, and archival Chandra data observed in 2000, 2008, and 2013.
- ID:
- ivo://CDS.VizieR/J/A+A/475/791
- Title:
- 12um ISOCAM survey of the ESO-Sculptor field
- Short Name:
- J/A+A/475/791
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a detailed reduction of a mid-infrared 12um (LW10 filter) ISOCAM open time observation performed on the ESO-Sculptor Survey field (Arnouts et al., 1997A&AS..124..163A). A complete catalogue of 142 sources (120 galaxies and 22 stars), detected with high significance (equivalent to 5{sigma}), is presented above an integrated flux density of 0.31mJy. Star/galaxy separation is performed by a detailed study of colour-colour diagrams. The catalogue is complete to 1mJy and, below this flux density, the incompleteness is corrected using two independent methods. The first method uses stars and the second uses optical counterparts of the ISOCAM galaxies; these methods yield consistent results. We also apply an empirical flux density calibration using stars in the field. For each star, the 12um flux density is derived by fitting optical colours from a multi-band {chi}^2^ to stellar templates (BaSel-2.0) and using empirical optical-IR colour-colour relations. This article is a companion analysis to our 2007 paper (Rocca-Volmerange et al. 2007A&A...475..801R) where the 12um faint galaxy counts are presented and analysed per galaxy type with the evolutionary code PEGASE.3.
- ID:
- ivo://CDS.VizieR/J/ApJ/870/104
- Title:
- 1-500um obs. of nearby luminous IR galaxies
- Short Name:
- J/ApJ/870/104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The interstellar medium is a key ingredient that governs star formation in galaxies. We present a detailed study of the infrared (~1-500{mu}m) spectral energy distributions of a large sample of 193 nearby (z~<0.088) luminous infrared galaxies (LIRGs) covering a wide range of evolutionary stages along the merger sequence. The entire sample has been observed uniformly by 2MASS, WISE, Spitzer, and Herschel. We perform a multicomponent decomposition of the spectra to derive physical parameters of the interstellar medium, including the intensity of the interstellar radiation field and the mass and luminosity of the dust. We also constrain the presence and strength of nuclear dust heated by active galactic nuclei. The radiation field of LIRGs tends to have much higher intensity than that of quiescent galaxies, and it increases toward advanced merger stages as a result of the central concentration of the interstellar medium and star formation. The total gas mass is derived from the dust mass and the galaxy stellar mass. We find that the gas fraction of LIRGs is on average ~0.3 dex higher than that of main-sequence star-forming galaxies, rising moderately toward advanced merger stages. All LIRGs have star formation rates that place them above the galaxy star formation main sequence. Consistent with recent observations and numerical simulations, the global star formation efficiency of the sample spans a wide range, filling the gap between normal star-forming galaxies and extreme starburst systems.
- ID:
- ivo://CDS.VizieR/J/ApJS/249/1
- Title:
- 500um risers with HerMES & SPIRE drop-outs with S2CLS
- Short Name:
- J/ApJS/249/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of our systematic search for the reddest far-infrared (FIR) and submillimeter (sub-mm) galaxies using the data from the Herschel Multi-tiered Extragalactic Survey (HerMES) and the SCUBA2 Cosmological Legacy Survey (S2CLS). The red FIR galaxies are "500{mu}m risers," whose spectral energy distributions increase with wavelength across the three FIR passbands of the Spectral and Photometric Imaging REceiver (SPIRE) of Herschel. Within 106.5deg^2^ of the HerMES fields, we have selected 629 500{mu}m risers. The red sub-mm galaxies are "SPIRE drop-outs," which are prominent detections in the S2CLS 850{mu}m data but are extremely weak or invisible in the SPIRE bands. Within the 2.98deg^2^ common area of HerMES and S2CLS, we have selected 95 such objects. These very red sources could be dusty starbursts at high redshifts (z>~4-6) because the peak of their cold-dust emission heated by star formation is shifted to the reddest FIR/sub-mm bands. The surface density of 500{mu}m risers is ~8.2deg^-2^ at the >=20mJy level in 500{mu}m, while that of SPIRE drop-outs is ~19.3deg^-2^ at the >=5mJy level in 850{mu}m. Both types of objects could span a wide range of redshifts, however. Using deep radio data in these fields to further select the ones likely at the highest redshifts, we find that the surface density of z>6 candidates is 5.5deg^-2^ among 500{mu}m risers and is 0.8-13.6deg^-2^ among SPIRE drop-outs. If this is correct, the dust-embedded star formation processes in such objects could contribute comparably as Lyman-break galaxies to the global SFR density at z>6.
- ID:
- ivo://CDS.VizieR/J/A+A/587/A160
- Title:
- 3.6um S4G Galactic bars characterization
- Short Name:
- J/A+A/587/A160
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stellar bars play an essential role in the secular evolution of disk galaxies because they are responsible for the redistribution of matter and angular momentum. Dynamical models predict that bars become stronger and longer in time, while their rotation speed slows down. We use the Spitzer Survey of Stellar Structure in Galaxies (S^4^G) 3.6um imaging to study the properties (length and strength) and fraction of bars at z=0 over a wide range of galaxy masses (M*~=10^8^-10^11^M_{sun}_) and Hubble types (-3<=T<=10). We calculated gravitational forces from the 3.6um images for galaxies with a disk inclination lower than 65{deg}. We used the maximum of the tangential-to-radial force ratio in the bar region (Qb) as a measure of the bar-induced perturbation strength for a sample of ~600 barred galaxies. We also used the maximum of the normalized m=2 Fourier density amplitude (A_2_^max^) and the bar isophotal ellipticity ({epsilon}) to characterize the bar. Bar sizes were estimated i) visually, ii) from ellipse fitting, iii) from the radii of the strongest torque, and iv) from the radii of the largest m=2 Fourier amplitude in the bar region. By combining our force calculations with the HI kinematics from the literature, we estimated the ratio of the halo-to-stellar mass (Mh/M*) within the optical disk and by further using the universal rotation curve models, we obtained a first-order model of the rotation curve decomposition of 1128 disk galaxies. We probe possible sources of uncertainty in our Qb measurements: the assumed scale height and its radial variation, the influence of the spiral arms torques, the effect of non-stellar emission in the bar region, and the dilution of the bar forces by the dark matter halo (our models imply that only ~10% of the disks in our sample are maximal). We find that for early- and intermediate-type disks (-3<=T<5), the relatively modest influence of the dark matter halo leads to a systematic reduction of the mean Qb by about 10-15%, which is of the same order as the uncertainty associated with estimating the vertical scale height. The halo correction on Qb becomes important for later types, implying a reduction of ~20-25% for T=7-10. Whether the halo correction is included or not, the mean Qb shows an increasing trend with T. However, the mean A_2_^max^ decreases for lower mass late-type systems. These opposing trends are most likely related to the reduced force dilution by bulges when moving towards later type galaxies. Nevertheless, when treated separately, both the early- and late-type disk galaxies show a strong positive correlation between Qb and A_2_^max^. For spirals the mean {epsilon}~0.5 is nearly independent of T, but it drops among S0s (~0.2). The Qb and {epsilon} show a relatively tight dependence, with only a slight difference between early and late disks. For spirals, all our bar strength indicators correlate with the bar length (scaled to isophotal size). Late-type bars are longer than previously found in the literature. The bar fraction shows a double-humped distribution in the Hubble sequence (~75% for Sab galaxies), with a local minimum at T=4 (~40%), and it drops for M*<~10^9.5-10^M_{sun}_. If we use bar identification methods based on Fourier decomposition or ellipse fitting instead of the morphological classification, the bar fraction decreases by ~30-50% for late-type systems with T>=5 and correlates with Mh/M*. Our Mh/M* ratios agree well with studies based on weak lensing analysis, abundance matching, and halo occupation distribution methods, under the assumption that the halo inside the optical disk contributes roughly a constant fraction of the total halo mass (~4%). We find possible evidence for the growth of bars within a Hubble time, as (1) bars in early-type galaxies show larger density amplitudes and disk-relative sizes than their intermediate-type counterparts, and (2) long bars are typically strong. We also observe two clearly distinct types of bars, between early- and intermediate-type galaxies (T<5) on one side, and the late-type systems on the other, based on the differences in the bar properties. Most likely this distinction is connected to the higher halo-to-stellar ratio that we observe in later types, which affects the disk stability properties.
- ID:
- ivo://CDS.VizieR/J/A+A/427/23
- Title:
- 14.3um survey in the Lockman Hole
- Short Name:
- J/A+A/427/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the image and catalogue of the 14.3{mu}m hallow survey of 0.55 square degrees in the region of the Lockman Hole (10h 52m 03s, +57{deg} 21' 46", J2000). The data have been analyzed with the recent algorithm by Lari et al. (2001, Cat. <J/MNRAS/325/1173>) conceived to exploit ISO data in an optimal way, especially in the case of shallow surveys with low redundancy. Photometry has been accurately evaluated through extensive simulations and also the absolute calibration has been checked using a set of 21 stars detected at 14.3{mu}m, optical, and near-IR bands.
- ID:
- ivo://CDS.VizieR/J/A+A/405/999
- Title:
- Unidentified infrared bands (UIR)
- Short Name:
- J/A+A/405/999
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a set of 6-12{mu}m ISOPHOT-S spectra of the general interstellar medium of the Milky Way. This part of the spectrum is dominated by a series of strong, wide emission features commonly called the Unidentified Infrared Bands (UIR). The sampled area covers the inner Milky Way from l=-60{deg} to +60{deg} with a ten-degree step in longitude and nominal latitudes b=0{deg}, +/-1{deg}. For each grid position the actual observed direction was selected from IRAS 100{mu}m maps to minimize contamination by point sources and molecular clouds.
1140. Updated 2MFGC catalog
- ID:
- ivo://CDS.VizieR/J/other/AstBu/70.24
- Title:
- Updated 2MFGC catalog
- Short Name:
- J/other/AstBu/70
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We spent a solid overview of the infrared and visual images 18020 2MFGC galaxies selected in the automatic mode of 1.64 million. Extended objects XSC-2MASS catalog with respect infrared axes, a/b>=3. This work is aimed at excluding "spurious" objects from the list of flattened galaxies. Browse more than 80000 images in different filters were able to identify 1512 (8.4% of the total) of such objects. Found duplicate in 2MASS measurements of 23 galaxies with, respectively, two rooms 2MFGC, and 3 flat galaxy, not accounted for in other directories and in close proximity with the three "spurious" galaxies. The main part of the excluded facilities accounted for magnitudes less Ks=13mag. They are characterized by small angular size, low surface brightness and the concentration index. Exception objects identified significantly reduced the spread of values in the two-dimensional distribution. Results of work in the form of notes will be placed in the astronomical database VizieR, NED, HYPERLEDA.
