- ID:
- ivo://CDS.VizieR/J/AJ/130/1145
- Title:
- YSO near-infrared properties
- Short Name:
- J/AJ/130/1145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-resolution (R~18000), high signal-to-noise ratio, 2{mu}m spectra of 52 IR-selected Class I and flat-spectrum young stellar objects in the Taurus-Auriga, {rho} Ophiuchi, Serpens, Perseus, and Corona Australis dark clouds. We detect key absorption lines in 41 objects and fit synthetic spectra generated from pre-main-sequence models to deduce the effective temperatures, surface gravities, near-IR veilings, rotation velocities, and radial velocities of each of these 41 sources.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/702/178
- Title:
- YSOs in the central 400pc of the Galaxy
- Short Name:
- J/ApJ/702/178
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The central kpc of the Milky Way might be expected to differ significantly from the rest of the Galaxy with regard to gasdynamics and the formation of young stellar objects (YSOs). We probe this possibility with mid-infrared observations obtained with Infrared Array Camera and Multiband Imaging Photometer on Spitzer and with Midcourse Space Experiment. We use color-color diagrams and spectral energy distribution (SED) fits to explore the nature of YSO candidates (including objects with 4.5um excesses possibly due to molecular emission). We use the SEDs of these sources to estimate their physical characteristics; their masses appear to range from ~10 to ~20M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/A+A/362/199
- Title:
- YSOs in the l=+45 ISOGAL field
- Short Name:
- J/A+A/362/199
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The 7 and 15{mu}m observations of the Galaxy obtained by the ISOGAL program offer an unique possibility to investigate and separate the different populations of stars in the Galactic Plane, in particular to study the population of low flux density YSOs which could not be detected with IRAS.
- ID:
- ivo://CDS.VizieR/J/MNRAS/432/3445
- Title:
- YSOs on HII complex Sh2-252
- Short Name:
- J/MNRAS/432/3445
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The optically bright, extended HII region Sh2-252 is a part of the Gemini OB1 association. This region is mainly composed of two small clusters NGC 2175s and Teu 136 and four CHII regions namely A, B, C and E. In this paper, an extensive survey of the star-forming complex Sh2-252 has been undertaken with an aim to explore its hidden young stellar population, its characteristics, spatial distribution, morphology of the region and finally to understand the star formation scenario of the complex for the first time. Spitzer-IRAC, MIPS photometry (3.6-24um) are combined with 2MASS-NIR and optical data sets to identify and classify the YSOs by their IR excess emission from their circumstellar material. From the well-fit models for each source derived from the SED fitting tool, we calculated the {chi}^2^ weighted model parameters such as the stellar mass (M*), temperature (T*), stellar age (t*), mass of the disc (Mdisc), disc accretion rate (dMdisc/dt), envelope accretion rate (dMenv/dt) presented in table1.dat.
- ID:
- ivo://CDS.VizieR/J/AJ/150/145
- Title:
- YSOVAR infrared photometry in GGD12-15
- Short Name:
- J/AJ/150/145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an IR-monitoring survey with the Spitzer Space Telescope of the star-forming region GGD 12-15. More than 1000 objects were monitored, including about 350 objects within the central 5', which is found to be especially dense in cluster members. The monitoring took place over 38 days and is part of the Young Stellar Object VARiability project. The region was also the subject of a contemporaneous 67 ks Chandra observation. The field includes 119 previously identified pre-main sequence star candidates. X-rays are detected from 164 objects, 90 of which are identified with cluster members. Overall, we find that about half the objects in the central 5' are young stellar objects (YSOs) based on a combination of their spectral energy distribution, IR variability, and X-ray emission. Most of the stars with IR excess relative to a photosphere show large amplitude (>0.1 mag) mid-infrared (mid-IR) variability. There are 39 periodic sources, and all but one is found to be a cluster member. Almost half of the periodic sources do not show IR excesses. Overall, more than 85% of the Class I, flat spectrum, and Class II sources are found to vary. The amplitude of the variability is larger in more embedded YSOs. Most of the Class I/II objects exhibit redder colors in a fainter state, which is compatible with time-variable extinction. A few become bluer when fainter, which can be explained with significant changes in the structure of the inner disk. A search for changes in the IR due to X-ray events is carried out, but the low number of flares prevented an analysis of the direct impact of X-ray flares on the IR light curves. However, we find that X-ray detected Class II sources have longer timescales for change in the MIR than a similar set of non-X-ray detected Class IIs.
- ID:
- ivo://CDS.VizieR/J/ApJ/813/78
- Title:
- z=4.5 and z=5.7 LAEs properties with Spitzer
- Short Name:
- J/ApJ/813/78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results from a stellar population modeling analysis of a sample of 162 z=4.5 and 14 z=5.7 Ly{alpha} emitting galaxies (LAEs) in the Bootes field, using deep Spitzer/IRAC data at 3.6 and 4.5 {mu}m from the Spitzer Ly{alpha} Survey, along with Hubble Space Telescope NICMOS and WFC3 imaging at 1.1 and 1.6 {mu}m for a subset of the LAEs. This represents one of the largest samples of high-redshift LAEs imaged with Spitzer IRAC. We find that 30/162 (19%) of the z=4.5 LAEs and 9/14 (64%) of the z=5.7 LAEs are detected at >=3{sigma} in at least one IRAC band. Individual z=4.5 IRAC-detected LAEs have a large range of stellar mass, from 5x10^8^-10^11^ M_{sun}_. One-third of the IRAC-detected LAEs have older stellar population ages of 100 Myr^-1^ Gyr, while the remainder have ages <100 Myr. A stacking analysis of IRAC-undetected LAEs shows this population to be primarily low mass (8-20x10^8^ M_{sun}_) and young (64-570 Myr). We find a correlation between stellar mass and the dust-corrected ultraviolet-based star formation rate (SFR) similar to that at lower redshifts, in that higher mass galaxies exhibit higher SFRs. However, the z=4.5 LAE correlation is elevated 4-5 times in SFR compared to continuum-selected galaxies at similar redshifts. The exception is the most massive LAEs which have SFRs similar to galaxies at lower redshifts suggesting that they may represent a different population of galaxies than the traditional lower-mass LAEs, perhaps with a different mechanism promoting Ly{alpha} photon escape.
1247. ZFIRE v1.0 data release
- ID:
- ivo://CDS.VizieR/J/ApJ/828/21
- Title:
- ZFIRE v1.0 data release
- Short Name:
- J/ApJ/828/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an overview and the first data release of ZFIRE, a spectroscopic redshift survey of star-forming galaxies that utilizes the MOSFIRE instrument on Keck-I to study galaxy properties in rich environments at 1.5<z<2.5. ZFIRE measures accurate spectroscopic redshifts and basic galaxy properties derived from multiple emission lines. The galaxies are selected from a stellar mass limited sample based on deep near infrared imaging (K_AB_<25) and precise photometric redshifts from the ZFOURGE and UKIDSS surveys as well as grism redshifts from 3DHST. Between 2013 and 2015, ZFIRE has observed the COSMOS and UDS legacy fields over 13 nights and has obtained 211 galaxy redshifts over 1.57<z<2.66 from a combination of nebular emission lines (such as H{alpha}, [NII], H{beta}, [OII], [OIII], and [SII]) observed at 1-2{mu}m. Based on our medium-band near infrared photometry, we are able to spectrophotometrically flux calibrate our spectra to ~10% accuracy. ZFIRE reaches 5{sigma} emission line flux limits of ~3x10^-18^erg/s/cm^2^ with a resolving power of R=3500 and reaches masses down to ~10^9^M_{sun}_. We confirm that the primary input survey, ZFOURGE, has produced photometric redshifts for star-forming galaxies (including highly attenuated ones) accurate to {Delta}z/(1+z_spec_)=0.015 with 0.7% outliers. We measure a slight redshift bias of <0.001, and we note that the redshift bias tends to be larger at higher masses. We also examine the role of redshift on the derivation of rest-frame colors and stellar population parameters from SED fitting techniques. The ZFIRE survey extends spectroscopically confirmed z~2 samples across a richer range of environments, here we make available the first public release of the data for use by the community.
- ID:
- ivo://CDS.VizieR/J/MNRAS/457/629
- Title:
- ZFOURGE catalogue of AGN candidates
- Short Name:
- J/MNRAS/457/629
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate active galactic nuclei (AGN) candidates within the FourStar Galaxy Evolution Survey (ZFOURGE) to determine the impact they have on star formation in their host galaxies. We first identify a population of radio, X-ray, and infrared-selected AGN by cross-matching the deep Ks-band imaging of ZFOURGE with overlapping multiwavelength data. From this, we construct a mass-complete (log(M*/M_{sun}_)>=9.75), AGN luminosity limited sample of 235 AGN hosts over z=0.2-3.2. We compare the rest-frame U-V versus V-J (UVJ) colours and specific star formation rates (sSFRs) of the AGN hosts to a mass-matched control sample of inactive (non-AGN) galaxies. UVJ diagnostics reveal AGN tend to be hosted in a lower fraction of quiescent galaxies and a higher fraction of dusty galaxies than the control sample. Using 160{mu}m Herschel PACS data, we find the mean specific star formation rate of AGN hosts to be elevated by 0.34-/-0.07dex with respect to the control sample across all redshifts. This offset is primarily driven by infrared-selected AGN, where the mean sSFR is found to be elevated by as much as a factor of ~5. The remaining population, comprised predominantly of X-ray AGN hosts, is found mostly consistent with inactive galaxies, exhibiting only a marginal elevation. We discuss scenarios that may explain these findings and postulate that AGN are less likely to be a dominant mechanism for moderating galaxy growth via quenching than has previously been suggested.
- ID:
- ivo://CDS.VizieR/J/ApJ/803/34
- Title:
- z~4-10 galaxies from HST legacy fields
- Short Name:
- J/ApJ/803/34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The remarkable Hubble Space Telescope (HST) data sets from the CANDELS, HUDF09, HUDF12, ERS, and BoRG/HIPPIES programs have allowed us to map the evolution of the rest-frame UV luminosity function (LF) from z~10 to z~4. We develop new color criteria that more optimally utilize the full wavelength coverage from the optical, near-IR, and mid-IR observations over our search fields, while simultaneously minimizing the incompleteness and eliminating redshift gaps. We have identified 5859, 3001, 857, 481, 217, and 6 galaxy candidates at z~4, z~5, z~6, z~7, z~8, and z~10, respectively, from the ~1000arcmin^2^ area covered by these data sets. This sample of >10000 galaxy candidates at z>=4 is by far the largest assembled to date with HST. The selection of z~4-8 candidates over the five CANDELS fields allows us to assess the cosmic variance; the largest variations are at z>=7. Our new LF determinations at z~4 and z~5 span a 6 mag baseline and reach to -16 AB mag. These determinations agree well with previous estimates, but the larger samples and volumes probed here result in a more reliable sampling of >L_{star}_ galaxies and allow us to reassess the form of the UV LFs. Our new LF results strengthen our earlier findings to 3.4{sigma} significance for a steeper faint-end slope of the UV LF at z>4, with {alpha} evolving from {alpha}=-1.64+/-0.04 at z~4 to {alpha}=-2.06+/-0.13 at z~7 (and {alpha}=-2.02+/-0.23 at z~8), consistent with that expected from the evolution of the halo mass function. We find less evolution in the characteristic magnitude M^*^ from z~7 to z~4 the observed evolution in the LF is now largely represented by changes in {phi}_{star}_. No evidence for a non-Schechter-like form to the z~4-8 LFs is found. A simple conditional LF model based on halo growth and evolution in the M/L ratio ({alpha}(1+z}^-1.5^) of halos provides a good representation of the observed evolution.
- ID:
- ivo://CDS.VizieR/J/PASJ/65/113
- Title:
- 0.006<=z<=0.8 IR galaxies with AKARI
- Short Name:
- J/PASJ/65/113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the 9 and 18um luminosity functions (LFs) of galaxies at 0.006<=z<=0.8 (with an average redshift of ~0.04) using the AKARI mid-infrared all-sky survey catalog. We selected 243 galaxies at 9um and 255 galaxies at 18um from the Sloan Digital Sky Survey (SDSS) spectroscopy region. These galaxies were then classified by their optical emission lines, such as the line width of H{alpha} or by their emission line ratios of [OIII]/H{beta} and [NII]/H{alpha} into five types: Type 1 active galactic nuclei (AGN) (Type 1); Type 2 AGN (Type 2); low-ionization narrow emission line galaxies (LINER); galaxies with both star formation and narrow-line AGN activity (composite galaxies); and star-forming galaxies (SF). We found that (i) the number density ratio of Type 2 to Type 1 AGNs is 1.73+/-0.36, which is larger than a result obtained from the optical LF and (ii) this ratio decreases with increasing 18um luminosity.
