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171. HI and OVI absorbers in nearby Universe
ID:
ivo://CDS.VizieR/J/ApJS/182/378
Title:
HI and OVI absorbers in nearby Universe
Short Name:
J/ApJS/182/378
Date:
21 Oct 2021
Publisher:
CDS
Description:
We analyze intergalactic HI and OVI absorbers with {nu}<5000km/s in Hubble Space Telescope and Far Ultraviolet Spectroscopic Explorer spectra of 76 active galactic nuclei. The baryons traced by HI/OVI absorption are clearly associated with the extended surroundings of galaxies; for impact parameters <400kpc they are 2-4 times more numerous as those inside the galaxies. This large reservoir of matter likely plays a major role in galaxy evolution. We tabulate the fraction of absorbers having a galaxy of a given luminosity within a given impact parameter ({rho}) and velocity difference ({Delta}v), as well as the fraction of galaxies with an absorber closer than a given {rho} and {Delta}v. We identify possible "void absorbers" ({rho}>3Mpc to the nearest L_*_ galaxy), although at v<2500km/s all absorbers are within 1.5Mpc of an L>0.1L_*_ galaxy. The absorber properties depend on {rho}, but the relations are not simple correlations.
172. Highly excited H2 in Comets
ID:
ivo://CDS.VizieR/J/ApJS/169/458
Title:
Highly excited H2 in Comets
Short Name:
J/ApJS/169/458
Date:
21 Oct 2021
Publisher:
CDS
Description:
Rotationally resolved molecular hydrogen transitions originating from excitation of highly excited rovibrational levels of the X^1^{SIGMA}^+^_g_ state have been systematically identified for the first time in the Far Ultraviolet Spectroscopic Explorer (FUSE) observation of comets C/2000 WM1 (LINEAR) and C/2001 A2 (LINEAR). Spectral assignments for the observed lines of H_2_ and other atomic and molecular species are given. All observed H_2_ transitions belong to the Lyman (B^1^{SIGMA}^+^_u_-X^1^{sigma}^+^_g_) and Werner (C^1^{PI}_u_-X^1^{SIGMA}^+^_g_) band systems. Resonant excitation of H_2_ by Ly{beta} and other solar lines is very limited.
173. Highly ionized plasmas in the Milky Way
ID:
ivo://CDS.VizieR/J/ApJ/727/46
Title:
Highly ionized plasmas in the Milky Way
Short Name:
J/ApJ/727/46
Date:
21 Oct 2021
Publisher:
CDS
Description:
The cooling transition temperature gas in the interstellar medium (ISM), traced by the high ions, SiIV, CIV, NV, and OVI, helps to constrain the flow of energy from the hot ISM with T>10^6^K to the warm ISM with T<2x10^4^K. We investigate the properties of this gas along the lines of sight to 38 stars in the Milky Way disk using 1.5-2.7km/s resolution spectra of SiIV, CIV, and NV absorption from the Space Telescope Imaging Spectrograph, and 15km/s resolution spectra of OVI absorption from the Far Ultraviolet Spectroscopic Explorer. The absorption by SiIV and CIV exhibits broad and narrow components while only broad components are seen in NV and OVI. The narrow components imply gas with T<7x10^4^K and trace two distinct types of gas.
174. High-redshift Ly{alpha} emitters
ID:
ivo://CDS.VizieR/J/ApJ/725/394
Title:
High-redshift Ly{alpha} emitters
Short Name:
J/ApJ/725/394
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an atlas of 88 z~5.7 and 30 z~6.5 Ly{alpha} emitters obtained from a wide-field narrowband survey. We combined deep narrowband imaging in 120{AA} bandpass filters centered at 8150{AA} and 9140{AA} with deep BVRIz broadband imaging to select high-redshift galaxy candidates over an area of 4180arcmin^2^. The goal was to obtain a uniform selection of comparable depth over the seven targeted fields in the two filters. For the GOODS-North region of the Hubble Deep Field-North field, we also selected candidates using a 120{AA} filter centered at 9210{AA}. We made spectroscopic observations with Keck DEIMOS of nearly all the candidates to obtain the final sample of Ly{alpha} emitters. At the 3.3{AA} resolution of the DEIMOS observations the asymmetric profile for Ly{alpha} emission can be clearly seen in the spectra of nearly all the galaxies. We show that the spectral profiles are surprisingly similar for many of the galaxies and that the composite spectral profiles are nearly identical at z=5.7 and z=6.5.
175. High resolution EUV spectrum of N_2_
ID:
ivo://CDS.VizieR/J/ApJS/211/28
Title:
High resolution EUV spectrum of N_2_
Short Name:
J/ApJS/211/28
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have analyzed high-resolution (FWHM=0.2{AA}) extreme-ultraviolet (EUV, 800-1350{AA}) laboratory emission spectra of molecular nitrogen excited by an electron impact at 20 and 100eV under (mostly) optically thin, single-scattering experimental conditions. A total of 491 emission features were observed from N_2_ electronic-vibrational transitions and atomic N I and N II multiplets and their emission cross sections were measured. Molecular emission was observed at vibrationally excited ground-state levels as high as v"=17, from the a^1^{Pi}_g_, b^1^{Pi}_u_, and b'^1^{Sigma}_u_^+^ excited valence states and the Rydberg series c'_n+1_^1^{Sigma}_u_^+^, c_n_^1^{Pi}_u_, and o_n_^1^{Pi}_u_ for n between 3 and 9. The frequently blended molecular emission bands were disentangled with the aid of a sophisticated and predictive quantum-mechanical model of excited states that includes the strong coupling between valence and Rydberg electronic states and the effects of predissociation. Improved model parameters describing electronic transition moments were obtained from the experiment and allowed for a reliable prediction of the vibrationally summed electronic emission cross section, including an extrapolation to unobserved emission bands and those that are optically thick in the experimental spectra. Vibrationally dependent electronic excitation functions were inferred from a comparison of emission features following 20 and 100eV electron-impact collisional excitation. The electron-impact-induced fluorescence measurements are compared with Cassini Ultraviolet Imaging Spectrograph observations of emissions from Titan's upper atmosphere.
176. High-z galaxy candidates in the HFF cluster fields
ID:
ivo://CDS.VizieR/J/ApJ/862/156
Title:
High-z galaxy candidates in the HFF cluster fields
Short Name:
J/ApJ/862/156
Date:
21 Oct 2021
Publisher:
CDS
Description:
Acting as powerful gravitational lenses, the strong lensing galaxy clusters of the deep Hubble Frontier Fields (HFF) program permit access to lower-luminosity galaxies lying at higher redshifts than hitherto possible. We analyzed the HFF to measure the volume density of Lyman-break galaxies at z>4.75 by identifying a complete and reliable sample up to z~10. A marked deficit of such galaxies was uncovered in the highly magnified regions of the clusters relative to their outskirts, implying that the magnification of the sky area dominates over additional faint galaxies magnified above the flux limit. This negative magnification bias is consistent with a slow rollover at the faint end of the UV luminosity function and it indicates a preference for Bose-Einstein condensate dark matter with a light boson mass of m_B_~10^-22^eV over standard cold dark matter. We emphasize that measuring the magnification bias requires no correction for multiply-lensed images (with typically three or more images per source), whereas directly reconstructing the luminosity function will lead to an overestimate unless such images can be exhaustively matched up, especially at the faint end that is only accessible in the strongly lensed regions. In addition, we detected a distinctive downward transition in galaxy number density at z>~8, which may be linked to the relatively late reionization reported by Planck. Our results suggests that JWST will likely peer into an "abyss" with essentially no galaxies detected in deep NIR imaging at z>10.
177. High-z LAEs and LBGs in SHARDS survey
ID:
ivo://CDS.VizieR/J/MNRAS/478/3740
Title:
High-z LAEs and LBGs in SHARDS survey
Short Name:
J/MNRAS/478/3740
Date:
11 Mar 2022 14:56:32
Publisher:
CDS
Description:
We have undertaken a comprehensive search for both Lyman alpha emitters (LAEs) and Lyman break galaxies (LBGs) in the Survey for High-z Absorption Red and Dead Sources (SHARDS) Survey of the Great Observatories Origins Deep Survey North field. SHARDS is a deep imaging survey, made with the 10.4m Gran Telescopio Canarias, employing 25 medium band filters in the range from 500 to 941nm. This is the first time that both LAEs and LBGs are surveyed simultaneously in a systematic way in a large field. We draw a sample of 1558 sources; 528 of them are LAEs. Most of the sources (1434) show rest-frame UV continua. A minority of them (124) are pure LAEs with virtually no continuum detected in SHARDS. We study these sources from z~3.35 up to z~6.8, well into the epoch of reionization. Note that surveys done with just one or two narrow band filters lack the possibility to spot the rest-frame UV continuum present in most of our LAEs. We derive redshifts, star formation rates, Ly{alpha} equivalent widths, and luminosity functions (LFs). Grouping within our sample is also studied, finding 92 pairs or small groups of galaxies at the same redshift separated by less than 60 comoving kpc. In addition, we relate 87 and 55 UV-selected objects with two known overdensities at z=4.05 and z=5.198, respectively. Finally, we show that surveys made with broad-band filters are prone to introduce many unwanted sources (~20 per cent interlopers), which means that previous studies may be overestimating the calculated LFs, specially at the faint end.
178. HLF photometric catalog in GOODS-S v2.0
ID:
ivo://CDS.VizieR/J/ApJS/244/16
Title:
HLF photometric catalog in GOODS-S v2.0
Short Name:
J/ApJS/244/16
Date:
21 Oct 2021
Publisher:
CDS
Description:
This manuscript describes the public release of the Hubble Legacy Fields (HLF) project photometric catalog for the extended GOODS-South region from the Hubble Space Telescope (HST) archival program AR-13252. The analysis is based on the version 2.0 HLF data release that now includes all ultraviolet (UV) imaging, combining three major UV surveys. The HLF data combines over a decade worth of 7475 exposures taken in 2635 orbits totaling 6.3Ms with the HST Advanced Camera for Surveys Wide Field Channel (ACS/WFC) and the Wide Field Camera 3 (WFC3) UVIS/IR Channels in the greater GOODS-S extragalactic field, covering all major observational efforts (e.g., GOODS, GEMS, CANDELS, ERS, UVUDF, and many other programs; see Illingworth+ arXiv:1606.00841). The HLF GOODS-S catalogs include photometry in 13 bandpasses from the UV (WFC3/UVIS F225W, F275W, and F336W filters), optical (ACS/WFC F435W, F606W, F775W, F814W and F850LP filters), to near-infrared (WFC3/IR F098M, F105W, F125W, F140W and F160W filters). Such a data set makes it possible to construct the spectral energy distributions (SEDs) of objects over a wide wavelength range from high-resolution mosaics that are largely contiguous. Here, we describe a photometric analysis of 186474 objects in the HST imaging at wavelengths 0.2-1.6{mu}m. We detect objects from an ultra-deep image combining the PSF-homogenized and noise-equalized F850LP, F125W, F140W, and F160W images, including Gaia astrometric corrections. SEDs were determined by carefully taking the effects of the point-spread function in each observation into account.
179. HNCO in planetary atmospheres.
ID:
ivo://CDS.VizieR/J/A+A/616/A150
Title:
HNCO in planetary atmospheres.
Short Name:
J/A+A/616/A150
Date:
21 Oct 2021
Publisher:
CDS
Description:
Time-resolved Fourier transform infrared emission spectroscopy, Fourier transform absorption infrared spectroscopy, and high-resolution UV-ViS emission spectroscopy have been exploited in order to characterize the chemistry of isocyanic acid (HNCO) under glow discharge conditions in planetary atmospheres. HNCO mixtures (i.e., composed of di-hydrogen or ammonia) have been investigated in order to unveil the possible reaction pathways leading to the synthesis of the key prebiotic molecule formamide (HCONH_2_), upon planetary atmospheres containing isocyanic acid in presence of di-hydrogen and, separately, of ammonia. In addition, ab initio Molecular Dynamics simulations coupled with a state-of-the-art metadynamics technique have been performed in order to identify the most likely chemical pathways connecting HNCO to formamide. It turned out that the direct hydrogenation of HNCO is thermodynamically favored. Incidentally, also the experimental results - supplied by a simplified kinetic model - proved the favorability of the reaction HNCO + H_2_ -> HCONH_2_ which, moreover, spontaneously takes place in unbiased ab initio Molecular Dynamics simulations carried out under the effect of intense electric fields.
180. Hot white dwarfs in GALEX-DR5
ID:
ivo://CDS.VizieR/J/MNRAS/411/2770
Title:
Hot white dwarfs in GALEX-DR5
Short Name:
J/MNRAS/411/2770
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present comprehensive catalogues of hot star candidates in the Milky Way (MW), selected from Galaxy Evolution Explorer (GALEX) far-UV (FUV; 1344-1786{AA}) and near-UV (NUV; 1771-2831{AA}) imaging. The FUV and NUV photometry allows us to extract the hottest stellar objects, in particular hot white dwarfs (WD), which are elusive at other wavelengths because of their high temperatures and faint optical luminosities. We generated catalogues of UV sources from two GALEX's surveys: All-Sky Imaging Survey (AIS; depth AB magnitude ~19.9/20.8 in FUV/NUV) and Medium-depth Imaging Survey (MIS; depth ~22.6/22.7mag). The two catalogues (from GALEX fifth data release) contain 65.3/12.6 million (AIS/MIS) unique UV sources with errorNUV<= 0.5 mag, over 21 435/1579deg^2^. We also constructed subcatalogues of the UV sources with matched optical photometry from Sloan Digital Sky Survey (SDSS; seventh data release): these contain 0.6/0.9 million (AIS/MIS) sources with errors <=0.3mag in both FUV and NUV, excluding sources with multiple optical counterparts, over an area of 7325/1103 deg2. All catalogues are available online. We then selected 28 319 (AIS)/9028 (MIS) matched sources with FUV-NUV<-0.13; this colour cut corresponds to stellar Teff hotter than ~18 000K (the exact value varying with gravity). An additional colour cut of NUV-r>0.1 isolates binaries with largely differing Teffs, and some intruding quasi-stellar objects (QSOs; more numerous at faint magnitudes). Available spectroscopy for a subsample indicates that hot-star candidates with NUV-r<0.1 (mostly 'single' hot stars) have negligible contamination by non-stellar objects. We discuss the distribution of sources in the catalogues, and the effects of error and colour cuts on the samples. The density of hot-star candidates increases from high to low Galactic latitudes, but drops on the MW plane due to dust extinction. Our hot-star counts at all latitudes are better matched by MW models computed with an initial-final mass relation (IFMR) that favours lower final masses. The model analysis indicates that the brightest sample is likely composed of WDs located in the thin disc, at typical distances between 0.15 and 1kpc, while the fainter sample comprises also a fraction of thick disc and halo stars. Proper motion distributions, available only for the bright sample (NUV<18mag), are consistent with the kinematics of a thin-disc population.