- ID:
- ivo://CDS.VizieR/J/ApJ/813/83
- Title:
- Multiple star formation in Ophiuchus
- Short Name:
- J/ApJ/813/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We conduct a multiplicity survey of members of the {rho} Ophiuchus cloud complex with high-resolution imaging to characterize the multiple-star population of this nearby star-forming region and investigate the relation between stellar multiplicity and star and planet formation. Our aperture masking survey reveals the presence of five new stellar companions beyond the reach of previous studies, but does not result in the detection of any new substellar companions. We find that 43+/-6% of the 114 stars in our survey have stellar-mass companions between 1.3 and 780 AU, while 7_-5_^+8^% host brown dwarf companions in the same interval. By combining this information with knowledge of disk-hosting stars, we show that the presence of a close binary companion (separation <40AU) significantly influences the lifetime of protoplanetary disks, a phenomenon previously seen in older star-forming regions. At the ~1-2Myr age of our Ophiuchus members ~2/3 of close binary systems have lost their disks, compared to only ~30% of single stars and wide binaries. This has a significant impact on the formation of giant planets, which are expected to require much longer than 1 Myr to form via core accretion and thus planets formed via this pathway should be rare in close binary systems.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/414/3084
- Title:
- Multi-waveband analysis of 12um galaxies
- Short Name:
- J/MNRAS/414/3084
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a multi-waveband analysis of a 126-galaxy sub-sample of the 12um galaxy sample (12MGS), for which we have carried out a detailed X-ray spectral analysis in a previous paper. We determine the activity class of the galaxies by way of optical-line ratio diagnostics and characterize the optical classes by their X-ray, 12um and [OIII] luminosities and X-ray spectral properties.
- ID:
- ivo://CDS.VizieR/J/MNRAS/441/1017
- Title:
- Multiwavelength photometry of 34 galaxies
- Short Name:
- J/MNRAS/441/1017
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a comparison of the physical properties of a rest-frame 250um selected sample of massive, dusty galaxies from 0<z<5.3. Our sample comprises 29 high-redshift submillimetre galaxies (SMGs) from the literature, and 843 dusty galaxies at z<0.5 from the Herschel-ATLAS, selected to have a similar stellar mass to the SMGs. The z>1 SMGs have an average SFR of 390^+80^_-70_M_{sun}_/yr which is 110 times that of the low-redshift sample matched in stellar mass to the SMGs (SFR=3.3+/-0.2M_{sun}_/yr). The SMGs harbour a substantial mass of dust (1.2^+0.3^_-0.2_x10^9^M_{sun}_), compared to (1.6+/-0.1)x10^8^M_{sun}_ for low-redshift dusty galaxies. At low redshifts the dust luminosity is dominated by the diffuse ISM, whereas a large fraction of the dust luminosity in SMGs originates from star-forming regions. At the same dust mass SMGs are offset towards a higher SFR compared to the low-redshift H-ATLAS galaxies. This is not only due to the higher gas fraction in SMGs but also because they are undergoing a more efficient mode of star formation, which is consistent with their bursty star-formation histories. The offset in SFR between SMGs and low-redshift galaxies is similar to that found in CO studies, suggesting that dust mass is as good a tracer of molecular gas as CO.
- ID:
- ivo://CDS.VizieR/J/ApJ/761/114
- Title:
- Multi-wavelength study of clusters of galaxies. II.
- Short Name:
- J/ApJ/761/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Galaxy clusters provide powerful laboratories for the study of galaxy evolution, particularly the origin of correlations of morphology and star formation rate (SFR) with density. We construct visible to MIR spectral energy distributions of galaxies in eight low-redshift (z<0.3) clusters and use them to measure stellar masses and SFRs as a function of environment. A partial correlation analysis indicates that the SFRs of star-forming galaxies (SFGs) depend strongly on M_*_ (>99% confidence) with no dependence on R/R_200_ or projected local density at fixed mass. A merged sample of galaxies from the five best measured clusters shows <SFR>{prop.to}(R/R_200_)^1.1+/-0.3^ for galaxies with R/R_200_<=0.4. A decline in the fraction of SFGs toward the cluster center contributes most of this effect, but it is accompanied by a reduction in <SFR> for SFGs with R<=0.1R_200_. The increase in the fraction of SFGs toward larger R/R_200_ and the isolation of SFGs with reduced SFRs near the cluster center are consistent with the truncation of star formation by ram-pressure stripping, as is the tendency for more massive SFGs to have higher SFRs. We conclude that stripping is more likely than slower processes to drive the properties of SFGs with R<0.4R_200_ in clusters. We also find that galaxies near the cluster center are more massive than galaxies farther out in the cluster at ~3.5{sigma}, which suggests that dynamical relaxation significantly impacts the distribution of cluster galaxies as the clusters evolve.
- ID:
- ivo://CDS.VizieR/J/MNRAS/425/1215
- Title:
- Multiwavelength survey of AGNs
- Short Name:
- J/MNRAS/425/1215
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim to study the effect of environment on the presence and fuelling of active galactic nuclei (AGNs) in massive galaxy clusters. We explore the use of different AGN detection techniques with the goal of selecting AGN across a broad range of luminosities, AGN/host galaxy flux ratios and obscuration levels. From a sample of 12 galaxy clusters at redshifts 0.5<z<0.9, we identify AGN candidates using optical variability from multi-epoch Hubble Space Telescope imaging, X-ray point sources in Chandra images and mid-infrared (IR) spectral energy distribution power-law fits through the Spitzer Infrared Array Camera channels. We find 178 optical variables, 74 X-ray point sources and 64 IR power-law sources, resulting in an average of ~25 AGN per cluster.
- ID:
- ivo://CDS.VizieR/J/ApJ/634/128
- Title:
- 16{mu}m imaging around the HDF-N
- Short Name:
- J/ApJ/634/128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a pilot study of 16{mu}m imaging within the GOODS northern field. Observations were obtained using the "peak-up" imaging capability of the Spitzer IRS. We survey 35arcmin^2^ to an average 3{sigma} depth of 0.075mJy and detect 149 sources.
- ID:
- ivo://CDS.VizieR/J/A+A/614/A33
- Title:
- 500{mu}m-risers sources
- Short Name:
- J/A+A/614/A33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Context. Over the last decade a large number of dusty star-forming galaxies has been discovered up to redshift z=2-3 and recent studies have attempted to push the highly confused Herschel SPIRE surveys beyond that distance. To search for z>=4 galaxies they often consider the sources with fluxes rising from 250{mu}m to 500{mu}m (so-called "500{mu}m-risers"). Herschel surveys offer a unique opportunity to efficiently select a large number of these rare objects, and thus gain insight into the prodigious star-forming activity that takes place in the very distant Universe. Aims. We aim to implement a novel method to obtain a statistical sample of 500{mu}m-risers and fully evaluate our selection inspecting different models of galaxy evolution. Methods. We consider one of the largest and deepest Herschel surveys, the Herschel Virgo Cluster Survey. We develop a novel selection algorithm which links the source extraction and spectral energy distribution fitting. To fully quantify selection biases we make end-to-end simulations including clustering and lensing. Results. We select 133 500{mu}m-risers over 55deg^2^, imposing the criteria: S_500_>S_350_>S_250_, S_250_>13.2mJy and S_500_>30mJy. Differential number counts are in fairly good agreement with models, displaying a better match than other existing samples. The estimated fraction of strongly lensed sources is 24_+6_^-5^% based on models.Conclusions. We present the faintest sample of 500{mu}m-risers down to S_250_=13.2mJy. We show that noise and strong lensing have an important impact on measured counts and redshift distribution of selected sources. We estimate the flux-corrected star formation rate density at 4<z<5 with the 500{mu}m-risers and find it to be close to the total value measured in far-infrared. This indicates that colour selection is not a limiting effect to search for the most massive, dusty z>4 sources.
- ID:
- ivo://CDS.VizieR/J/ApJ/634/L1
- Title:
- 16{mu}m sources in the NOAO Bootes field
- Short Name:
- J/ApJ/634/L1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the 16{mu}m peak-up imager on the Infrared Spectrograph (IRS) on Spitzer, we present a serendipitous survey of 0.0392{deg}^2^ within the area of the NOAO Deep Wide-Field Survey in Bootes. Combining our results with the available Multiband Imaging Photometer for Spitzer (MIPS) 24{mu}m survey of this area, we produce a catalog of 150 16{mu}m sources brighter than 0.18mJy (3{sigma}) for which we derive measures or limits on the 16{mu}m/24{mu}m colors. Such colors are especially useful in determining redshifts for sources whose mid-infrared spectra contain strong emission or absorption features that characterize these colors as a function of redshift.
- ID:
- ivo://CDS.VizieR/J/ApJS/209/30
- Title:
- MYStIX project: Bayesian matching
- Short Name:
- J/ApJS/209/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Identifying the infrared counterparts of X-ray sources in Galactic plane fields such as those of the MYStIX project presents particular difficulties due to the high density of infrared sources. This high stellar density makes it inevitable that a large fraction of X-ray positions will have a faint field star close to them, which standard matching techniques may incorrectly take to be the counterpart. Instead we use the infrared data to create a model of both the field star and counterpart magnitude distributions, which we then combine with a Bayesian technique to yield a probability that any star is the counterpart of an X-ray source. In our more crowded fields, between 10% and 20% of counterparts that would be identified on the grounds of being the closest star to an X-ray position within a 99% confidence error circle are instead identified by the Bayesian technique as field stars. These stars are preferentially concentrated at faint magnitudes. Equally importantly the technique also gives a probability that the true counterpart to the X-ray source falls beneath the magnitude limit of the infrared catalog. In deriving our method, we place it in the context of other procedures for matching astronomical catalogs.
- ID:
- ivo://CDS.VizieR/J/MNRAS/509/2377
- Title:
- Narrow-Line Seyfert 1 IR Survey
- Short Name:
- J/MNRAS/509/2377
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present a near-infrared spectroscopic survey of narrow-line Seyfert 1 galaxies in the southern hemisphere (using the SOFI instrument on the ESO-NTT telescope), sampled from optical surveys. We examine the kinematics of the broad-line region, probed by the emission line width of hydrogen (Paschen{alpha} and H{beta}). We observed 57 objects, of which we could firmly measure Paschen{alpha} in 49 cases. We find that a single Lorentzian fit (preferred on theoretical grounds) is preferred over multi-component Gaussian fits to the line profiles; a lack of narrow-line region emission, overwhelmed by the pole-on view of the broad line region (BLR) light, supports this. We recompute the catalog black hole (BH) mass estimates, using the values of FWHM and luminosity of H{beta}, both from catalog values and re-fitted Lorentzian values. We find a relationship slope greater than unity compared to the catalog values. We ascribe this to contamination by galactic light or difficulties with line flux measurements. However, the comparison of masses computed by the fitted Lorentzian and Gaussian measurements show a slope close to unity. Comparing the BH masses estimated from both Paschen{alpha} and H{beta}, the line widths and fluxes shows deviations from expected; in general, however, the computed BH masses are comparable. We posit a scenario where an intermixture of dusty and dust-free clouds (or alternately a structured atmosphere) differentially absorbs the line radiation of the BLR, due to dust absorption and hydrogen bound-free absorption.