- ID:
- ivo://CDS.VizieR/J/ApJ/679/194
- Title:
- Low-z intergalactic medium. III.
- Short Name:
- J/ApJ/679/194
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We conduct an ultraviolet (HST and FUSE) spectroscopic survey of HI (Lyman lines) and seven metal ions (OVI, NV, CIV, CIII, SiIV, SiIII, FeIII) in the low-redshift IGM at z<0.4. We analyzed 650 Ly{alpha} absorbers over redshift path length {Delta}z=5.27, detecting numerous absorbers: 83 OVI systems, 39 CIII, 53 SiIII, 24 CIV, 24 NV, and so on. In the low-z IGM, we have accounted for ~40% of the baryons: 30% in the photoionized Ly{alpha} forest and 10% in the (T=10^5^-10^6^) WHIM traced by OVI. Statistical metallicities are consistent with the canonical value of 10% solar, with considerable scatter.
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- ID:
- ivo://CDS.VizieR/J/A+A/575/A57
- Title:
- LQ Hya activity and Li variations
- Short Name:
- J/A+A/575/A57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the rotational modulation of chromospheric and photospheric parameters of the young, active, single K2 dwarf LQ Hya and their connection with the variability of the LiI 670.8nm line. A total of 199 high-resolution STELLA spectra were used to compute effective temperature, gravity, and chromospheric activity indicators like H{alpha} and H{beta} emission, Balmer decrement, and chromospheric electron density, as a function of the rotational phase. The variation of the LiI 670.8nm line were characterized in terms of equivalent width, abundance, and of ^6^Li/^7^Li isotopic ratio in the form of line shifts.
- ID:
- ivo://CDS.VizieR/J/A+A/599/A76
- Title:
- L-{sigma} relation for HII galaxies
- Short Name:
- J/A+A/599/A76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The correlation between emission-line luminosity (L) and profile-width ({sigma}) for HII galaxies provides a powerful method to measure the distances to galaxies over a wide range of redshifts. In this paper, we use SDSS spectrophotometry to explore the systematics of the correlation using the [OIII]5007 lines instead of H{alpha} or H{beta} to measure luminosities and line widths. We also examine possible systematic effects involved in measuring the profile-widths and the luminosities through different apertures. We find that the green L-{sigma} relation, defined using [OIII]5007 luminosities, is significantly more sensitive than H{beta} to the effects of age and the physical conditions of the nebulae, which more than offsets the advantage of the higher strength of the [OIII]5007 lines. We then explore the possibility of mixing [OIII]5007 profile-widths with SDSS H{beta} luminosities using the Hubble constant H_0_ to quantify the possible systematic effects. We find the mixed L(H{beta})-{sigma}_[OIII]_ relation to be at least as powerful as the canonical L-{sigma} relation as a distance estimator, and we show that evolutionary corrections do not change the slope and the scatter of the correlation and, therefore, do not bias the L-{sigma} distance indicator at high redshifts. Locally, however, the luminosities of the giant HII regions that provide the zero-point calibrators are sensitive to evolutionary corrections and may bias the Hubble constant if their mean ages, as measured by the equivalent widths of H{beta}, are significantly different from the mean age of the HII galaxies. Using a small sample of 16 ad-hoc zero point calibrators we obtain a value of H_0_=66.4^+5.0^_-4.5_km/s/Mpc for the Hubble constant, which is fully consistent with the best modern determinations, and which is not biased by evolutionary corrections.
- ID:
- ivo://CDS.VizieR/J/MNRAS/442/3565
- Title:
- L-{sigma} relation for massive star formation
- Short Name:
- J/MNRAS/442/3565
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The validity of the emission-line luminosity versus ionized gas velocity dispersion (L-{sigma}) correlation for HII galaxies (HIIGx) and its potential as an accurate distance estimator are assessed. For a sample of 128 local (0.02<~z<~0.2) compact HIIGx with high equivalent widths of their Balmer emission lines, we obtained the ionized gas velocity dispersion from high signal-to-noise ratio (S/N) high-dispersion spectroscopy (Subaru High Dispersion Spectrograph (HDS) and European Southern Observatory (ESO) Very Large Telescope Ultraviolet and Visual Echelle Spectrograph (VLT-UVES)) and integrated H{beta} fluxes from low-dispersion wide aperture spectrophotometry. We find that the L(H{beta})-{sigma} relation is strong and stable against restrictions in the sample (mostly based on the emission-line profiles). The `Gaussianity' of the profile is important for reducing the root-mean-square (rms) uncertainty of the distance indicator, but at the expense of substantially reducing the sample. By fitting other physical parameters into the correlation, we are able to decrease the scatter significantly without reducing the sample. The size of the star-forming region is an important second parameter, while adding the emission-line equivalent width or the continuum colour and metallicity produces the solution with the smallest rms scatter={delta}logL(H{beta})=0.233. The derived coefficients in the best L(H{beta})-{sigma} relation are very close to what is expected from virialized ionizing clusters, while the derived sum of the stellar and ionized gas masses is similar to the dynamical mass estimated using the Hubble Space Telescope} (HST}) corrected Petrosian radius. These results are compatible with gravity being the main mechanism causing the broadening of the emission lines in these very young and massive clusters. The derived masses range from about 2x10^6^M_{sun}_ to 10^9^M_{sun}_ and their 'corrected' Petrosian radius ranges from a few tens to a few hundred pc.
- ID:
- ivo://CDS.VizieR/J/ApJ/656/437
- Title:
- LS I +61 303 radial velocities and Halpha EW
- Short Name:
- J/ApJ/656/437
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of an Halpha monitoring campaign on the BeXRB and microquasar system LS I +61 303. We use radial velocity measurements of HeI lines in our spectra to reevaluate the orbital elements and to better establish the time of periastron. We list equivalent widths and other parameters for the Halpha emission line and discuss the orbital phase related variations observed.
- ID:
- ivo://CDS.VizieR/J/ApJ/656/431
- Title:
- LS I +65 010 radial velocities and Halpha EW
- Short Name:
- J/ApJ/656/431
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on a 3yr spectroscopic monitoring program of the Halpha emission in the massive X-ray binary LS I +65 010 = 2S 0114+650, which consists of a B supergiant and a slowly rotating X-ray pulsar. We present revised orbital elements that yield a period of P=11.5983+/-0.0006days and confirm that the orbit has a nonzero eccentricity e=0.18+/-0.05. The Halpha emission profile is formed in the base of the wind of the B supergiant primary, and we show how this spectral feature varies on timescales that are probably related to the rotational period of the B supergiant. We also examine the X-ray fluxes from the Rossi X-ray Timing Explorer All-Sky Monitor instrument, and we show that the X-ray orbital light curve has a maximum at periastron and a minimum at the inferior conjunction of the B supergiant. We also show that the wind emission strength and the high-energy X-ray flux appear to vary in tandem on timescales of approximately 1yr.
- ID:
- ivo://CDS.VizieR/J/A+A/617/A130
- Title:
- Luminous infrared galaxies AKARI 2.5-5um data
- Short Name:
- J/A+A/617/A130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present AKARI 2.5-5um spectra of 145 local luminous infrared galaxies (LIRG; L_IR_>=10^11^L_{sun}_) in the Great Observatories All-sky LIRG Survey (GOALS). In all of the spectra, we measure the line fluxes and equivalent widths (EQWs) of the polycyclic aromatic hydrocarbon (PAH) at 3.3um and the hydrogen recombination line Br{alpha} at 4.05um, with apertures matched to the slit sizes of the Spitzer low-resolution spectrograph and with an aperture covering ~95% of the total flux in the AKARI two-dimensional (2D) spectra. The star formation rates (SFRs) derived from the Br{alpha} emission measured in the latter aperture agree well with SFRs estimated from LIR, when the dust extinction correction is adopted based on the 9.7um silicate absorption feature. Together with the Spitzer Infrared Spectrograph (IRS) 5.2-38um spectra, we are able to compare the emission of the PAH features detected at 3.3um and 6.2um. These are the two most commonly used near/mid-infrared indicators of starburst or active galactic nucleus (AGN) dominated galaxies. We find that the 3.3um and 6.2um PAH EQWs do not follow a linear correlation and at least a third of the galaxies classified as AGN-dominated sources using the 3.3um feature are classified as starbursts based on the 6.2um feature. These galaxies have a bluer continuum slope than galaxies that are indicated to be starburst-dominated by both PAH features. The bluer continuum emission suggests that their continuum is dominated by stellar emission rather than hot dust. We also find that the median Spitzer/IRS spectra of these sources are remarkably similar to the pure starburst-dominated sources indicated by high PAH EQWs in both 3.3um and 6.2um. Based on these results, we propose a revised starburst/AGN diagnostic diagram using 2-5um data: the 3.3um PAH EQW and the continuum color, F{nu}(4.3um)/F{nu}(2.8um). We use the AKARI and Spitzer spectra to examine the performance of our new starburst/AGN diagnostics and to estimate 3.3um PAH fluxes using the James Webb Space Telescope (JWST) photometric bands in the redshift range 0<z<5. Of the known PAH features and mid-infrared high ionization emission lines used as starburst/AGN indicators, only the 3.3um PAH feature is observable with JWST at z>3.5, because the rest of the features at longer wavelengths fall outside the JWST wavelength coverage.
- ID:
- ivo://CDS.VizieR/J/MNRAS/477/2817
- Title:
- Luminous Ly{alpha} emitters at z~2-3
- Short Name:
- J/MNRAS/477/2817
- Date:
- 02 Mar 2022 00:40:05
- Publisher:
- CDS
- Description:
- Deep narrow-band surveys have revealed a large population of faint Ly{alpha} emitters (LAEs) in the distant Universe, but relatively little is known about the most luminous sources (L_Lya_>~10^42.7^erg/s; L_Lya>~L^*^_Lya_). Here we present the spectroscopic follow-up of 21 luminous LAEs at z~2-3 found with panoramic narrow-band surveys over five independent extragalactic fields (=~4x10^6^Mpc^3^ surveyed at z~2.2 and z~3.1). We use WHT/ISIS, Keck/DEIMOS, and VLT/X-SHOOTER to study these sources using high ionization UV lines. Luminous LAEs at z~2-3 have blue UV slopes ({beta}=-2.0^+0.3^_-0.1_) and high Ly{alpha} escape fractions (50^+20^_-15_ per cent) and span five orders of magnitude in UV luminosity (M_UV_=~-19 to -24). Many (70 per cent) show at least one high ionization rest-frame UV line such as CIV, NV, CIII], HeII or OIII], typically blue-shifted by =~100-200km/s relative to Ly{alpha}. Their Ly{alpha} profiles reveal a wide variety of shapes, including significant blue-shifted components and widths from 200 to 4000km/s. Overall, 60+/-11 per cent appear to be active galactic nucleus (AGN) dominated, and at L_Lya_>10^43.3^erg/s and/or M_UV_<-21.5 virtually all LAEs are AGNs with high ionization parameters (logU=0.6+/-0.5) and with metallicities of =~0.5-1Z_{sun}_. Those lacking signatures of AGNs (40+/-11 per cent) have lower ionization parameters (logU=-3.0^+1.6^_-0.9_ and log{xi}_ion_=25.4+/-0.2) and are apparently metal-poor sources likely powered by young, dust-poor 'maximal' starbursts. Our results show that luminous LAEs at z~2-3 are a diverse population and that 2xL^*^_Lya_ and 2*M_UV_^*^ mark a sharp transition in the nature of LAEs, from star formation dominated to AGN dominated.
- ID:
- ivo://CDS.VizieR/J/ApJ/888/89
- Title:
- Lya galaxies in 3 CFHTLS overdense regions
- Short Name:
- J/ApJ/888/89
- Date:
- 25 Oct 2021 10:16:31
- Publisher:
- CDS
- Description:
- We have carried out follow-up spectroscopy on three overdense regions of g- and r-dropout galaxies in the Canada-France-Hawaii Telescope Legacy Survey Deep Fields, finding two new protoclusters at z=4.898 and 3.721 and a possible protocluster at z=3.834. The z=3.721 protocluster overlaps with a previously identified protocluster at z=3.675. The redshift separation between these two protoclusters is {Delta}z=0.05, which is slightly larger than the size of typical protoclusters. Therefore, if they are not the progenitors of a >10^15^M_{sun}_ halo, they would grow into closely located independent halos like a supercluster. The other protocluster at z=4.898 is also surrounded by smaller galaxy groups. These systems including protoclusters and neighboring groups are regarded as the early phase of superclusters. We quantify the spatial distribution of member galaxies of the protoclusters at z=3.675 and 3.721 by fitting triaxial ellipsoids, finding a tentative difference: one has a pancake-like shape, while the other is filamentary. This could indicate that these two protoclusters are in different stages of formation. We investigate the relation between redshift and the velocity dispersion of protoclusters, including other protoclusters from the literature, in order to compare their dynamical states. Although there is no significant systematic trend in the velocity dispersions of protoclusters with redshift, the distribution is skewed to higher velocity dispersion over the redshift range of z=2-6. This could be interpreted as two phases of cluster formation, one dominated by the steady accretion of galaxies and the other by the merging between group-size halos, perhaps depending on the surrounding large-scale environments.
- ID:
- ivo://CDS.VizieR/J/ApJ/559/654
- Title:
- Ly{alpha} absorption systems. V.
- Short Name:
- J/ApJ/559/654
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a program to obtain and analyze HST WFPC2 images and ground-based images of galaxies identified in an imaging and spectroscopic survey of faint galaxies in fields of HST spectroscopic target QSOs. Here we present the additional HST WFPC2 observations of galaxies in 10 QSO fields that were not included in Paper I (Chen et al., 1998, Cat. <J/ApJ/498/77>) and near-infrared imaging observations of galaxies in 15 QSO fields.
