- ID:
- ivo://CDS.VizieR/J/ApJ/882/138
- Title:
- ALMA Spectroscopic Survey in the HUDF (ASPECS)
- Short Name:
- J/ApJ/882/138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the results from the ALMA large program ASPECS, the spectroscopic survey in the Hubble Ultra Deep Field (HUDF), to constrain CO luminosity functions of galaxies and the resulting redshift evolution of {rho}(H_2_). The broad frequency range covered enables us to identify CO emission lines of different rotational transitions in the HUDF at z>1. We find strong evidence that the CO luminosity function evolves with redshift, with the knee of the CO luminosity function decreasing in luminosity by an order of magnitude from ~2 to the local universe. Based on Schechter fits, we estimate that our observations recover the majority (up to ~90%, depending on the assumptions on the faint end) of the total cosmic CO luminosity at z=1.0-3.1. After correcting for CO excitation, and adopting a Galactic CO-to-H_2_ conversion factor, we constrain the evolution of the cosmic molecular gas density {rho}(H_2_): this cosmic gas density peaks at z~1.5 and drops by a factor of 6.5_-1.4_^+1.8^ to the value measured locally. The observed evolution in {rho}(H_2_), therefore, closely matches the evolution of the cosmic star formation rate density {rho}SFR. We verify the robustness of our result with respect to assumptions on source inclusion and/or CO excitation. As the cosmic star formation history can be expressed as the product of the star formation efficiency and the cosmic density of molecular gas, the similar evolution of {rho}(H_2_) and {rho}SFR leaves only little room for a significant evolution of the average star formation efficiency in galaxies since z~3 (85% of cosmic history).
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/122/221
- Title:
- A mid-IR survey of Proto-PNs Candidates
- Short Name:
- J/ApJS/122/221
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the data from a mid-infrared (MIR) imaging survey of 66 proto-planetary nebula candidates using two MIR cameras (MIRAC2 and Berkcam) at the NASA Infrared Telescope Facility and the United Kingdom Infrared Telescope. The goal of this survey is to determine the size, flux, and morphology of the MIR emission regions, which sample the inner regions of the circumstellar dust shells of protoplanetary nebulae. We imaged these protoplanetary nebulae with narrowband filters({delta}{lambda}/{lambda}{=~}10%) at wavelengths of notable dust features. With our typical angular resolution of 1'', we resolve 17 sources, find 48 objects unresolved, and do not detect one source. For several sources we checked optical and infrared associations and positions of the sources. In table format, we list the size and flux measurements for all of the detected objects and show figures of all of the resolved sources. The proto-planetary nebula candidate sample includes, in addition to the predominant proto-planetary nebulae, extreme asymptotic giant branch stars, young planetary nebulae, a supergiant, and a luminous blue variable. We find that dust shells that are cooler (T{=~}150 K) and brighter in the infrared are more easily resolved. Eleven of the seventeen resolved sources are extended and fall into one of two types of MIR morphological classes: core/elliptical or toroidal. Core/elliptical structures show unresolved cores with lower surface brightness elliptical nebulae. Toroidal structures show limb-brightened peaks suggesting equatorial density enhancements. We argue that core/ellipticals have denser dust shells than toroidals.
- ID:
- ivo://CDS.VizieR/J/A+A/462/507
- Title:
- AMIGA III. IRAS data
- Short Name:
- J/A+A/462/507
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the mid- (MIR) and far- (FIR) infrared properties of a large (~1000) sample of the most isolated galaxies in the local Universe. This sample is intended as a "nurture-free" zero point against which more environmentally influenced samples can be compared. We reprocess IRAS MIR/FIR survey data using the ADDSCAN/SCANPI utility for 1030 out of 1050 galaxies from the Catalogue of Isolated Galaxies (CIG, Cat. <VII/82>) as part of the AMIGA survey. We focus on diagnostics (FIR luminosity LFIR , R=log(LFIR/LB) and IRAS colours) thought to be sensitive to effects of environment or interaction.
- ID:
- ivo://CDS.VizieR/J/ApJ/900/9
- Title:
- AMIGA: The Circumgalactic Medium of Andromeda
- Short Name:
- J/ApJ/900/9
- Date:
- 14 Mar 2022 07:38:05
- Publisher:
- CDS
- Description:
- Project AMIGA (Absorption Maps In the Gas of Andromeda) is a survey of the circumgalactic medium (CGM) of Andromeda (M31, R_vir_~300kpc) along 43 QSO sightlines at impact parameters 25<~R<~569kpc (25 at R<~R_vir_). We use ultraviolet absorption measurements of SiII, SiIII, SiIV, CII, and CIV from the Hubble Space Telescope/Cosmic Origins Spectrograph and OVI from the Far Ultraviolet Spectroscopic Explorer to provide an unparalleled look at how the physical conditions and metals are distributed in the CGM of M31. We find that SiIII and OVI have a covering factor near unity for R<~1.2R_vir_ and <~1.9R_vir_, respectively, demonstrating that M31 has a very extended ~104-105.5K ionized CGM. The metal and baryon masses of the 104-105.5K CGM gas within R_vir_ are >~108 and >~4x1010 (Z/0.3Z{sun})-1M{sun}, respectively. There is not much azimuthal variation in the column densities or kinematics, but there is with R. The CGM gas at R<~0.5R_vir_ is more dynamic and has more complicated, multiphase structures than at larger radii, perhaps a result of more direct impact of galactic feedback in the inner regions of the CGM. Several absorbers are projected spatially and kinematically close to M31 dwarf satellites, but we show that those are unlikely to give rise to the observed absorption. Cosmological zoom simulations of ~L* galaxies have OVI extending well beyond R_vir_ as observed for M31 but do not reproduce well the radial column density profiles of the lower ions. However, some similar trends are also observed, such as the lower ions showing a larger dispersion in column density and stronger dependence on R than higher ions. Based on our findings, it is likely that the Milky Way has a ~104-105.5K CGM as extended as for M31 and their CGM (especially the warm-hot gas probed by OVI) are overlapping.
- ID:
- ivo://CDS.VizieR/J/A+A/486/73
- Title:
- AMIGA VII. FIR and radio study
- Short Name:
- J/A+A/486/73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper is part of a series involving the AMIGA project (Analysis of the Interstellar Medium of Isolated GAlaxies). This project provides a statistically-significant sample of the most isolated galaxies in the northern sky. We present a study of the nuclear activity in a well-defined sample of the most isolated galaxies (total sample: n=1050, complete subsample: n=719) in the local Universe traced by their far-infrared (FIR) and radio continuum emission. We use the well-known radio continuum-FIR correlation to select radio-excess galaxies that are candidates to host an active galactic nucleus (AGN), as well as the FIR colours to find obscured AGN-candidates. We also used the existing information on nuclear activity in the Veron-Cetty catalogue and in the NASA Extragalactic Database. A final catalogue of AGN-candidate galaxies has been produced that will provide a baseline for studies on the dependence of activity on the environment. Our sample is mostly radio quiet, consistent with its high content of late-type galaxies. At most ~1.5% of the galaxies show a radio excess with respect to the radio-FIR correlation, and this fraction even goes down to less than 0.8% after rejection of back/foreground sources using FIRST. We find that the fraction of FIR colour selected AGN-candidates is ~28% with a lower limit of ~7%. Our final catalogue contains 89 AGN candidates and is publicly available on the AMIGA web page (http://www.iaa.csic.es/AMIGA.html).
- ID:
- ivo://CDS.VizieR/J/ApJ/885/64
- Title:
- Amplitude of variability for 150 YSOs in Orion
- Short Name:
- J/ApJ/885/64
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a quantitative, empirically based argument that at least some Class I sources are low-mass, pre-main-sequence stars surrounded by spatially extended envelopes of dusty gas. The source luminosity arises principally from stellar gravitational contraction, as in optically visible pre-main-sequence stars that lack such envelopes. We base our argument on the fact that some Class I sources in Orion and other star-forming regions have been observed by Spitzer to be periodic variables in the mid-infrared, and with periods consistent with T Tauri rotation rates. Using a radiative transfer code, we construct a variety of dust envelopes surrounding rotating, spotted stars, to see whether an envelope that produces a Class I spectral energy distribution at least broadly matches the observed modulations in luminosity. Acceptable envelopes can be either spherical or flattened and may or may not have polar cavities. The key requirement is that they have a modest equatorial optical depth at the Spitzer waveband of 3.6{mu}m, typically {tau}3.6~0.6. The total envelope mass, based on this limited study, is at most about 0.1M{sun}, less than a typical stellar mass. Future studies should focus on the dynamics of the envelope, to determine whether material is actually falling onto the circumstellar disk.
- ID:
- ivo://CDS.VizieR/III/153
- Title:
- An Atlas of Near Infrared Stellar Spectra
- Short Name:
- III/153
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The atlas represents a collection of spectra in the wavelength range 2.00 to 2.45 micrometers having a resolution of approximately 0.02 micrometers. The sample of 73 stars includes a supergiant, giants, dwarfs, and subdwarfs with a chemical abundance range of about -2 to +0.5 dex.
- ID:
- ivo://CDS.VizieR/J/ApJS/248/18
- Title:
- 44 and 95GHz observations of class I methanol masers
- Short Name:
- J/ApJS/248/18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report a simultaneous 44 and 95GHz class I methanol maser survey toward 144 sources from the 95GHz class I methanol maser catalog. The observations were made with the three telescopes of the Korean very long baseline interferometry network operating in single-dish mode. The detection rates are 89% at 44GHz and 77% at 95GHz. There are 106 new discoveries at 44GHz. Comparing the previous 95GHz detections with new observations of the same transitions made using the Purple Mountain Observatory 13.7m radio telescope shows no clear evidence of variability on a timescale of six years. Emission from the 44 and 95GHz transitions shows strong correlations in peak velocity, peak flux density, and integrated flux density, indicating that they are likely cospatial. We found that the peak flux density ratio S_pk,95_/S_pk,44_ decreases as the 44GHz peak flux density increases. We found that some class I methanol masers in our sample might be associated with infrared dark clouds, while others are associated with HII regions, indicating that some sources occur at an early stage of high-mass star formation, while others are located toward more evolved sources.
- ID:
- ivo://CDS.VizieR/J/A+A/490/213
- Title:
- 1.4 and 3.4mm interferometry of W3 IRS5
- Short Name:
- J/A+A/490/213
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of PdBI 1.4 and 3.4mm interferometric observations of the high-mass star-forming region W3 IRS5 in the AB configurations. From the continuum maps we identified five individual sources with counterparts in the NIR, MIR or radio (Q-band), except for one source that is a new identification. Three of the sources are within the inner 2100AU, where the protostellar number density exceeds 10^6^ protostars pc^-3^ assuming spherical symmetry. Lower limits for the circumstellar masses of the sources range from ~0.3 to ~40M_{sun}_ although they were strongly affected by the spatial filtering of the interferometer. We mapped the SiO(2-1), SiO(5-4), SO2(22-22), and SO2(8-9) molecular transitions. We identify five molecular outflows in SiO, two of them nearly in the line of sight direction. The SO2 velocity structure indicates a rotating, bound system, and we find tentative signatures of converging flows as predicted by the gravoturbulent star formation and converging flow theories. The obtained data strongly indicate that the clustered environment has a major influence on the formation of high-mass stars; however, our data do not clearly allow us to distinguish whether the ongoing star-forming process follows a monolithic collapse or a competitive accretion mechanism.
- ID:
- ivo://CDS.VizieR/J/A+A/608/A102
- Title:
- APEX CO and HI observations of Lupus I
- Short Name:
- J/A+A/608/A102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Lupus I cloud is found between the Upper Scorpius (USco) and Upper Centaurus-Lupus (UCL) subgroups of the Scorpius-Centaurus OB association, where the expanding USco HI shell appears to interact with a bubble currently driven by the winds of the remaining B stars of UCL. Aims. We investigate whether the Lupus I molecular could have formed in a colliding flow, and in particular, how the kinematics of the cloud might have been influenced by the larger scale gas dynamics. We performed APEX ^13^CO(2-1)and C^18^O(2-1) line observations of three distinct parts of Lupus I that provide kinematic information on the cloud at high angular and spectral resolution. We compare those results to the atomic hydrogen data from the GASS HI survey and our dust emission results presented in the previous paper. Based on the velocity information, we present a geometric model for the interaction zone between the USco shell and the UCL wind bubble. We present evidence that the molecular gas of Lupus Iis tightly linked to the atomic material of the USco shell. The CO emission in Lupus Iis found mainly at velocities between v_LSR_=3-6km/s, which is in the same range as the HI velocities. Thus, the molecular cloud is co-moving with the expanding USco atomic HI shell. The gas in the cloud shows a complex kinematic structure with several line-of-sight components that overlay each other. The nonthermal velocity dispersion is in the transonic regime in all parts of the cloud and could be injected by external compression. Our observations and the derived geometric model agree with a scenario in which Lupus Iis located in the interaction zone between the USco shell and the UCL wind bubble. The kinematics observations are consistent with a scenario in which the Lupus Icloud formed via shell instabilities. The particular location of Lupus I between USco and UCL suggests that counterpressure from the UCL wind bubble and pre-existing density enhancements, perhaps left over from the gas stream that formed the stellar subgroups, may have played a role in its formation.
