- ID:
- ivo://CDS.VizieR/J/ApJ/843/31
- Title:
- MUSCLES Treasury Survey. IV. M dwarf UV fluxes
- Short Name:
- J/ApJ/843/31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Characterizing the UV spectral energy distribution (SED) of an exoplanet host star is critically important for assessing its planet's potential habitability, particularly for M dwarfs, as they are prime targets for current and near-term exoplanet characterization efforts and atmospheric models predict that their UV radiation can produce photochemistry on habitable zone planets different from that on Earth. To derive ground-based proxies for UV emission for use when Hubble Space Telescope (HST) observations are unavailable, we have assembled a sample of 15 early to mid-M dwarfs observed by HST and compared their nonsimultaneous UV and optical spectra. We find that the equivalent width of the chromospheric Ca II K line at 3933{AA}, when corrected for spectral type, can be used to estimate the stellar surface flux in ultraviolet emission lines, including HI Ly{alpha}. In addition, we address another potential driver of habitability: energetic particle fluxes associated with flares. We present a new technique for estimating soft X-ray and >10MeV proton flux during far-UV emission line flares (Si IV and He II) by assuming solar-like energy partitions. We analyze several flares from the M4 dwarf GJ 876 observed with HST and Chandra as part of the MUSCLES Treasury Survey and find that habitable zone planets orbiting GJ 876 are impacted by large Carrington-like flares with peak soft X-ray fluxes >=10^-3^W/m^2^ and possible proton fluxes ~10^2^-10^3^pfu, approximately four orders of magnitude more frequently than modern-day Earth.
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- ID:
- ivo://CDS.VizieR/J/A+A/654/A80
- Title:
- MUSE Catalog of UV emission line measurement
- Short Name:
- J/A+A/654/A80
- Date:
- 02 Feb 2022 10:08:10
- Publisher:
- CDS
- Description:
- Rest-frame ultraviolet (UV) emission lines probe electron densities, gas-phase abundances, metallicities, and ionization parameters of the emitting star-forming galaxies and their environments. The strongest main UV emission line, Ly{alpha}, has been instrumental in advancing the general knowledge of galaxy formation in the early universe. However, observing Ly{alpha} emission becomes increasingly challenging at z>~6 when the neutral hydrogen fraction of the circumgalactic and intergalactic media increases. Secondary weaker UV emission lines provide important alternative methods for studying galaxy properties at high redshift. We present a large sample of rest-frame UV emission line sources at intermediate redshift for calibrating and exploring the connection between secondary UV lines and the emitting galaxies' physical properties and their Ly{alpha} emission. The sample of 2052 emission line sources with 1.5<z<6.4 was collected from integral field data from the MUSE-Wide and MUSE-Deep surveys taken as part of Guaranteed Time Observations. The objects were selected through untargeted source detection (i.e., no preselection of sources as in dedicated spectroscopic campaigns) in the three-dimensional MUSE data cubes. We searched optimally extracted one-dimensional spectra of the full sample for UV emission features via emission line template matching, resulting in a sample of more than 100 rest-frame UV emission line detections. We show that the detection efficiency of (non-Ly{alpha}) UV emission lines increases with survey depth, and that the emission line strength of HeII {lambda}1640AA, [OIII] {lambda}1661 + OIII] {lambda}1666, and [SiIII] {lambda}1883 + SiIII] {lambda}1892 correlate with the strength of [CIII] {lambda}1907 + CIII] {lambda}1909. The rest-frame equivalent width (EW0 ) of [CIII] {lambda}1907+CIII] {lambda}1909 is found to be roughly 0.22+/-0.18 of EW0 (Ly{alpha}). We measured the velocity offsets of resonant emission lines with respect to systemic tracers. For CIV {lambda}1548 + CIV {lambda}1551 we find that {DELTA}v_CIV_<~250km/s, whereas {nu}v_Ly{alpha}_ falls in the range of 250-500km/s which is in agreement with previous results from the literature. The electron density ne measured from [SiIII] {lambda}1883 + SiIII] {lambda}1892 and [CIII] {lambda}1907 + CIII] {lambda}1909 line flux ratios is generally <10^5^cm^-3^ and the gas-phase abundance is below solar at 12+log10(O/H)~=8. Lastly, we used "PhotoIonization Model Probability Density Functions" to infer physical parameters of the full sample and individual systems based on photoionization model parameter grids and observational constraints from our UV emission line searches. This reveals that the UV line emitters generally have ionization parameter log10(U) ~= -2.5 and metal mass fractions that scatter around Z~=10-2, that is Z~=0.66Z_{sun}_. Value-added catalogs of the full sample of MUSE objects studied in this work (this catalog) and a collection of UV line emitters from the literature are provided with this paper.
- ID:
- ivo://CDS.VizieR/J/A+A/659/A183
- Title:
- MUSE-Wide+MUSE-Deep EWs of Lyman{alpha} emitters
- Short Name:
- J/A+A/659/A183
- Date:
- 25 Mar 2022 09:08:03
- Publisher:
- CDS
- Description:
- The hydrogen Lyman{alpha} line is often the only measurable feature in optical spectra of high-redshift galaxies. Its shape and strength are influenced by radiative transfer processes and the properties of the underlying stellar population. High equivalent widths of several hundred {AA} are especially hard to explain by models and could point towards unusual stellar populations, for example with low metallicities, young stellar ages, and a top-heavy initial mass function. Other aspects influencing equivalent widths are the morphology of the galaxy and its gas properties. The aim of this study is to better understand the connection between the Lyman{alpha} rest-frame equivalent width (EW0) and spectral properties as well as ultraviolet (UV) continuum morphology by obtaining reliable EW0 histograms for a statistical sample of galaxies and by assessing the fraction of objects with large equivalent widths. We used integral field spectroscopy from the Multi Unit Spectroscopic Explorer (MUSE) combined with broad-band data from the Hubble Space Telescope (HST) to measure EW0 . We analysed the emission lines of 1920 Lyman{alpha} emitters (LAEs) detected in the full MUSE-Wide (one hour exposure time) and MUSE-Deep (ten hour exposure time) surveys and found UV continuum counterparts in archival HST data. We fitted the UV continuum photometric images using the Galfit software to gain morphological information on the rest-UV emission and fitted the spectra obtained from MUSE to determine the double peak fraction, asymmetry, full-width at half maximum, and flux of the Lyman{alpha} line. The two surveys show different histograms of Lyman{alpha} EW0 . In MUSE-Wide, 20% of objects have EW0>240{AA}, while this fraction is only 11% in MUSE-Deep and ~=16% for the full sample. This includes objects without HST continuum counterparts (one-third of our sample), for which we give lower limits for EW0. The object with the highest securely measured EW0 has EW0=589+/-193{AA} (the highest lower limit being EW0=4464{AA}). We investigate the connection between EW0 and Lyman{alpha} spectral or UV continuum morphological properties. The survey depth has to be taken into account when studying EW0 distributions. We find that in general, high EW0 objects can have a wide range of spectral and UV morphological properties, which might reflect that the underlying causes for high EW0 values are equally varied.
- ID:
- ivo://CDS.VizieR/J/A+A/489/533
- Title:
- M83 volume densities of giant molecular clouds
- Short Name:
- J/A+A/489/533
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using observed GALEX far-ultraviolet (FUV) fluxes and VLA images of the 21-cm HIcolumn densities, along with estimates of the local dust abundances, we measure the volume densities of a sample of actively star-forming giant molecular clouds (GMCs) in the nearby spiral galaxy M83 on a typical resolution scale of 170 pc. Our approach is based on an equilibrium model for the cycle of molecular hydrogen formation on dust grains and photodissociation under the influence of the FUV radiation on the cloud surfaces of GMCs. We find a range of total volume densities on the surface of GMCs in M83, namely 0.1-400cm^-3^ inside R_25_, 0.5-50cm^-3^ outside R_25_. Our data include a number of GMCs in the HI-ring surrounding this galaxy. Finally, we discuss the effects of observational selection, which may bias our results.
- ID:
- ivo://CDS.VizieR/J/A+A/307/869
- Title:
- Nature of the peculiar supergiant HD 101584
- Short Name:
- J/A+A/307/869
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of low- and high-resolution ultraviolet, high-resolution optical CAT/CES spectra and ultraviolet, optical and infrared photometry of the peculiar supergiant HD 101584. From the photometry we learn that the ultraviolet and optical energy distribution cannot be fitted in a consistent way and we need a model in which the UV and optical energy distribution are formed by different gas. The Geneva photometry is best fitted to a B9II Kurucz model, T_eff_=12000+/-1000K and logg=3.0+/-1.0, with an extinction of E(B-V)=0.49+/-0.05. The observed spectral features in the spectrum of HD 101584 are classified in eight different categories based on the velocity, shape of profile and the identification. The high-excitation HeI ({chi}=20.87eV), NII ({chi}=18.40eV), CII ({chi}=14.39eV) and NI ({chi}=10.29eV) optical absorption lines are formed in the photosphere of a late B-star (e.g. B8-9I-II). These absorption lines show radial velocity variations which are attributed to binary motion, with the secondary being a white dwarf or a low-mass main sequence object. The low-excitation P-Cygni lines in the optical and UV are formed in the wind. The number density of absorption lines in the UV is so large that the wind spectrum acts as an iron curtain in front of the B-star. The terminal velocity of the wind of v_{infinity}_=100+/-30km/s is consistent with the star being a low-mass post-AGB star and the low effective gravity is attributed to the presence of a nearby, unseen, secondary. We estimate a mass-loss rate of M{dot}=~10^-8^M_{sun}_/yr. Narrow absorption and emission lines are observed which are formed in a circumsystem disk with a typical radius of 10^2^R_*_.
- ID:
- ivo://CDS.VizieR/J/ApJS/155/257
- Title:
- NBC Quasar Candidate Catalog
- Short Name:
- J/ApJS/155/257
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of 100563 unresolved, UV-excess (UVX) quasar candidates to g=21 from 2099 deg^2^ of the Sloan Digital Sky Survey (SDSS) Data Release One (DR1) imaging data. Existing spectra of 22737 sources reveals that 22191 (97.6%) are quasars; accounting for the magnitude dependence of this efficiency, we estimate that 95502 (95.0%) of the objects in the catalog are quasars. Such a high efficiency is unprecedented in broadband surveys of quasars. This "proof-of-concept" sample is designed to be maximally efficient, but still has 94.7% completeness to unresolved, g~<19.5, UVX quasars from the DR1 quasar catalog. This efficient and complete selection is the result of our application of a probability density type analysis to training sets that describe the four-dimensional color distribution of stars and spectroscopically confirmed quasars in the SDSS. Specifically, we use a nonparametric Bayesian classification, based on kernel density estimation, to parameterize the color distribution of astronomical sources - allowing for fast and robust classification. We further supplement the catalog by providing photometric redshifts and matches to FIRST/VLA, ROSAT, and USNO-B sources.
- ID:
- ivo://CDS.VizieR/J/ApJ/814/40
- Title:
- Nearby galaxy filaments with UV obs.
- Short Name:
- J/ApJ/814/40
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Simulations of the formation of large-scale structures predict that dark matter, low density highly ionized gas, and galaxies form 10 to 40Mpc scale filaments. These structures are easily recognized in the distribution of galaxies. Here we use Ly{alpha} absorption lines to study the gas in 30x6Mpc filament at cz~3500km/s, defined using a new catalog of nearby (cz<10000km/s) galaxies, which is complete down to a luminosity of about 0.05L_*_ for the region of space analyzed here. Using Hubble Space Telescope spectra of 24 active galactic nuclei, we sample the gas in this filament. All of our sightlines pass outside the virial radius of any known filament galaxy. Within 500kpc of the filament axis the detection rate is ~80%, but no detections are seen more than 2.1Mpc from the filament axis. The width of the Ly{alpha} lines correlates with filament impact parameter and the four BLAs in our sample occur within 400kpc of the filament axis, indicating increased temperature and/or turbulence. Comparing to simulations, we find that the recent Haardt & Madau extragalactic ionizing background predicts a factor of 3-5 too few ionizing photons. Using a more intense radiation field matches the hydrogen density profile within 2.1Mpc of the filament axis, but the simulations still overpredict the detection rate between 2.1 and 5Mpc from the axis. The baryonic mass inside filament galaxies is 1.4x10^13^M_{sun}_, while the mass of filament gas outside galaxy halos is found to be 5.2x10^13^M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/ApJS/229/23
- Title:
- New FeI level energies from stellar spectra. II.
- Short Name:
- J/ApJS/229/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Fe I spectrum is critical to many areas of astrophysics, yet many of the high-lying levels remain uncharacterized. To remedy this deficiency, Peterson & Kurucz (2015, J/ApJS/216/1) identified Fe I lines in archival ultraviolet and optical spectra of metal-poor stars, whose warm temperatures favor moderate Fe I excitation. Sixty-five new levels were recovered, with 1500 detectable lines, including several bound levels in the ionization continuum of Fe I. Here, we extend the previous work by identifying 59 additional levels, with 1400 detectable lines, by incorporating new high-resolution UV spectra of warm metal-poor stars recently obtained by the Hubble Space Telescope Imaging Spectrograph. We provide gf values for these transitions, both computed as well as adjusted to fit the stellar spectra. We also expand our spectral calculations to the infrared, confirming three levels by matching high-quality spectra of the Sun and two cool stars in the H-band. The predicted gf values suggest that an additional 3700 Fe I lines should be detectable in existing solar infrared spectra. Extending the empirical line identification work to the infrared would help confirm additional Fe I levels, as would new high-resolution UV spectra of metal-poor turnoff stars below 1900{AA}.
- ID:
- ivo://CDS.VizieR/J/ApJS/206/17
- Title:
- New gamma-ray blazar candidates in the 3PBC
- Short Name:
- J/ApJS/206/17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We searched for {gamma}-ray blazar candidates among the 382 unidentified hard X-ray sources of the third Palermo BAT Catalog (3PBC) obtained from the analysis of 66 months of Swift Burst Alert Telescope (BAT) survey data and listing 1586 sources. We adopted a recently developed association method based on the peculiar infrared colors that characterize the {gamma}-ray blazars included in the second catalog of active galactic nuclei detected by the Fermi Large Area Telescope. We used this method exploiting the data of the all-sky survey performed by the Wide-field Infrared Survey Explorer (WISE) to establish correspondences between unidentified 3PBC sources and WISE {gamma}-ray blazar candidates located within the BAT positional uncertainty region at a 99% confidence level. We obtained a preliminary list of candidates for which we analyzed all the available data in the Swift archive to complement the information in the literature and in the radio, infrared, and optical catalogs with the information on their optical-UV and soft X-ray emission. Requiring the presence of radio and soft X-ray counterparts consistent with the infrared positions of the selected WISE sources, as well as a blazar-like radio morphology, we finally obtained a list of 24 {gamma}-ray blazar candidates.
290. NGC4395 light curves
- ID:
- ivo://CDS.VizieR/J/ApJ/632/799
- Title:
- NGC4395 light curves
- Short Name:
- J/ApJ/632/799
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A reverberation-mapping program on NGC 4395, the least luminous known Seyfert 1 galaxy, undertaken with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope yields a measurement of the mass of the central black hole M_BH_=(3.6+/-1.1)x10^5^M_{sun}_. The observations consist of two visits of five orbits each, in 2004 April and July. During each of these visits, the UV continuum varied by at least 10% (rms), and only C IV {lambda}1549 showed corresponding variations large enough to reliably determine the emission-line lag, which was measured to be of order 1-hr for both visits.
