- ID:
- ivo://CDS.VizieR/J/ApJ/869/123
- Title:
- Keck Lyman continuum spectroscopic survey (KLCS)
- Short Name:
- J/ApJ/869/123
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a deep spectroscopic survey quantifying the statistics of the escape of ionizing radiation from star-forming galaxies at z~3. We measure the ratio of ionizing to non-ionizing UV flux density <f_900_/f_1500_>_obs_, where f_900_ is the mean flux density evaluated over the range [880,910]{AA}. We quantify the emergent ratio of ionizing to non-ionizing UV flux density by analyzing high signal-to-noise ratio composite spectra formed from subsamples with common observed properties and numbers sufficient to reduce the statistical uncertainty in the modeled IGM+CGM correction to obtain precise values of <f_900_/f_1500_>_out_, including a full-sample average <f_900_/f_1500>_out_=0.057{+/-}0.006. We show that <f_900_/f_1500_>_out_ increases monotonically with W_{lambda}_(Ly{alpha}), inducing an inverse correlation with UV luminosity as a by-product. We fit the composite spectra using stellar spectral synthesis together with models of the ISM in which a fraction f_c_ of the stellar continuum is covered by gas with column density N_HI_. We show that the composite spectra simultaneously constrain the intrinsic properties of the stars (L_900_/L_1500_)_int_ along with f_c_, N_HI_, E(B-V), and f_esc,abs_, the absolute escape fraction of ionizing photons. We find a sample-averaged f_esc,abs_=0.09{+/-}0.01, with subsamples falling along a linear relation <f_esc,abs_>~0.75[W_{lambda}_(Ly{alpha})/110{AA}]. Using the far-UV luminosity function, the distribution function n(W(Ly{alpha})), and the relationship between W_{lambda}_(Ly{alpha}) and <f_900_/f_1500_>_out_, we estimate the total ionizing emissivity of z~3 star-forming galaxies with M_uv_<=-19.5, which exceeds the contribution of quasi-stellar objects by a factor of ~3, and accounts for ~50% of the total {epsilon}LyC at z~3 estimated using indirect methods.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/221/2
- Title:
- Keck+Magellan survey for LLSs. III.
- Short Name:
- J/ApJS/221/2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an absorption-line survey of optically thick gas clouds --Lyman Limit Systems (LLSs)-- observed at high dispersion with spectrometers on the Keck and Magellan telescopes. We measure column densities of neutral hydrogen N_H1_ and associated metal-line transitions for 157 LLSs at z_LLS_=1.76-4.39 restricted to 10^17.3^cm^-2^<=N_HI_<10^20.3^cm^-2^. An empirical analysis of ionic ratios indicates an increasing ionization state of the gas with decreasing N_H1_ and that the majority of LLSs are highly ionized, confirming previous expectations. The Si^+^/H^0^ ratio spans nearly four orders of magnitude, implying a large dispersion in the gas metallicity. Fewer than 5% of these LLSs have no positive detection of a metal transition; by z~3 nearly all gas that is dense enough to exhibit a very high Lyman limit opacity has previously been polluted by heavy elements. We add new measurements to the small subset of LLS (~5%-10%) that may have super-solar abundances. High Si^+^/Fe^+^ ratios suggest an {alpha}-enhanced medium, whereas the Si^+^/C^+^ ratios do not exhibit the super-solar enhancement inferred previously for the Ly{alpha} forest.
- ID:
- ivo://CDS.VizieR/J/ApJ/834/101
- Title:
- Keck/MOSFIRE spectroscopy of ZFOURGE galaxies
- Short Name:
- J/ApJ/834/101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compare galaxy scaling relations as a function of environment at z~2 with our ZFIRE survey where we have measured H{alpha} fluxes for 90 star-forming galaxies selected from a mass-limited (log(M_*_/M_{sun}_)>9) sample based on ZFOURGE. The cluster galaxies (37) are part of a confirmed system at z=2.095 and the field galaxies (53) are at 1.9<z<2.4; all are in the COSMOS legacy field. There is no statistical difference between H{alpha}-emitting cluster and field populations when comparing their star formation rate (SFR), stellar mass (M_*_), galaxy size (r_eff_), SFR surface density ({Sigma}(H{alpha}_star_)), and stellar age distributions. The only difference is that at fixed stellar mass, the H{alpha}-emitting cluster galaxies are log(r_eff_)~0.1 larger than in the field. Approximately 19% of the H{alpha} emitters in the cluster and 26% in the field are IR-luminous (L_IR_>2x10^11^L_{sun}_). Because the luminous IR galaxies in our combined sample are ~5 times more massive than the low-IR galaxies, their radii are ~70% larger. To track stellar growth, we separate galaxies into those that lie above, on, or below the H{alpha} star-forming main sequence (SFMS) using {Delta}SFR(M*)=+/-0.2dex. Galaxies above the SFMS (starbursts) tend to have higher H{alpha} SFR surface densities and younger light-weighted stellar ages than galaxies below the SFMS. Our results indicate that starbursts (+SFMS) in the cluster and field at z~2 are growing their stellar cores. Lastly, we compare to the (SFR-M*) relation from Rhapsody-G cluster simulations and find that the predicted slope is nominally consistent with the observations. However, the predicted cluster SFRs tend to be too low by a factor of ~2, which seems to be a common problem for simulations across environment.
- ID:
- ivo://CDS.VizieR/J/ApJ/893/4
- Title:
- KiDS ultracompact massive galaxies sp. obs.
- Short Name:
- J/ApJ/893/4
- Date:
- 03 Dec 2021 00:37:06
- Publisher:
- CDS
- Description:
- Ultracompact massive galaxies (UCMGs), i.e., galaxies with stellar masses M_*_>8x10^10^M_{sun}_ and effective radii R_e_<1.5kpc, are very rare systems, in particular at low and intermediate redshifts. Their origin as well as their number density across cosmic time are still under scrutiny, especially because of the paucity of spectroscopically confirmed samples. We have started a systematic census of UCMG candidates within the ESO Kilo Degree Survey, together with a large spectroscopic follow-up campaign to build the largest possible sample of confirmed UCMGs. This is the third paper of the series and the second based on the spectroscopic follow-up program. Here, we present photometrical and structural parameters of 33 new candidates at redshifts 0.15<~z<~0.5 and confirm 19 of them as UCMGs, based on their nominal spectroscopically inferred M_*_ and R_e_. This corresponds to a success rate of ~58% , nicely consistent with our previous findings. The addition of these 19 newly confirmed objects allows us to fully assess the systematics on the system selection-and to finally reduce the number density uncertainties. Moreover, putting together the results from our current and past observational campaigns and some literature data, we build the largest sample of ucmgs ever collected, comprising 92 spectroscopically confirmed objects at 0.1<~z<~0.5. This number raises to 116, allowing for a 3{sigma} tolerance on the M_*_ and R_e_ thresholds for the ucmg definition. For all these galaxies, we have estimated the velocity dispersion values at the effective radii, which have been used to derive a preliminary mass-velocity dispersion correlation.
- ID:
- ivo://CDS.VizieR/J/AJ/109/874
- Title:
- Kinematics of MKW and AWM Poor Clusters
- Short Name:
- J/AJ/109/874
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report 472 new redshifts for 416 galaxies in the regions of the 23 poor clusters of galaxies originally identified by Morgan, Kayser, and White, and Albert, White and Morgan. Eighteen of the poor clusters now have 10 or more available redshifts within 1.5h^-1 Mpc of the central galaxy; 11 clusters have at least 20 available redshifts. Based on the 21 clusters for which we have sufficient velocity information, the median velocity scale is 336 km/s, a factor of 2 smaller than found for rich clusters. Several of the poor clusters exhibit complex velocity distributions due to the presence of nearby clumps of galaxies. We check on the velocity of the dominant galaxy in each poor cluster relative to the remaining cluster members. Significantly high relative velocities of the dominant galaxy are found in only 4 of 21 poor clusters, 3 of which we suspect are due to contamination of the parent velocity distribution. Several statistical tests indicate that the D/cD galaxies are at the kinematic centers of the parent poor cluster velocity distributions. Mass-to-light ratios for 13 of the 15 poor clusters for which we have the required data are in the range 50 <= M/L_B(0) <= 200 Msun/Lsun. The complex nature of the regions surrounding many of the poor clusters suggests that these groupings may represent an early epoch of cluster formation. For example, the poor clusters MKW7 and MKW8 are shown to be gravitationally bound and likely to merge to form a richer cluster within the next several Gyrs. Eight of the nine other poor clusters for which simple two-body dynamical models can be carried out are consistent with being bound to other clumps in their vicinity. Additional complex systems with more than two gravitationally bound clumps are observed among the poor clusters.
- ID:
- ivo://CDS.VizieR/J/AJ/130/496
- Title:
- KISS emission-line galaxy candidates
- Short Name:
- J/AJ/130/496
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectroscopic observations for 315 emission-line galaxy (ELG) candidates from the KPNO International Spectroscopic Survey (KISS) have been obtained using the MDM Observatory 2.4m telescope on Kitt Peak. KISS is a wide-field objective-prism survey for extragalactic emission-line objects that has cataloged over 2200 ELG candidates to date. Spectroscopic follow-up observations are being carried out to study the characteristics of the survey objects. The observational data presented here include redshifts, reddening estimates, line equivalent widths, H{alpha} line fluxes, and emission-line ratios. The galaxies have been classified based on their emission-line characteristics.
- ID:
- ivo://CDS.VizieR/J/AJ/130/2584
- Title:
- KISS emission-line galaxy candidates. IV
- Short Name:
- J/AJ/130/2584
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectroscopic observations for 614 emission-line galaxy (ELG) candidates from the KPNO International Spectroscopic Survey (KISS) have been obtained using the KPNO 2.1m telescope and the WIYN 3.5m telescope. KISS is a wide-field objective-prism survey for extragalactic emission-line objects that has cataloged over 2400 ELG candidates to date. Spectroscopic follow-up observations are being carried out at several telescopes to study the characteristics of the survey objects. We present the following data derived from the KPNO spectra: redshifts, reddening estimates, line equivalent widths, H{alpha} line fluxes, and emission-line ratios. The galaxies have been classified based on their emission-line characteristics.
- ID:
- ivo://CDS.VizieR/J/AJ/121/66
- Title:
- KISS H{alpha} survey list 1
- Short Name:
- J/AJ/121/66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The KPNO International Spectroscopic Survey (KISS) is a new objective-prism survey for extragalactic emission-line objects. It combines many of the features of previous slitless spectroscopic surveys with the advantages of modern CCD detectors and is the first purely digital objective-prism survey for emission-line galaxies. Here we present the first list of emission-line galaxy candidates selected from our red spectral data, which cover the spectral range 6400 to 7200{AA}. In most cases, the detected emission line is H{alpha}. The current survey list covers a 1{deg}-wide strip located at {delta}= 29{deg} 30' (B1950.0) and spanning the right ascension range 12h 15m to 17h 0m. An area of 62.2{deg}^2^ is covered. A total of 1128 candidate emission-line objects have been selected for inclusion in the survey list (18.1{deg}^-2^). We tabulate accurate coordinates and photometry for each source, as well as estimates of the redshift and emission-line flux and equivalent width based on measurements of the digital objective-prism spectra. The properties of the KISS emission-line galaxies are examined using the available observational data.
- ID:
- ivo://CDS.VizieR/J/AJ/123/1292
- Title:
- KISS III. [O III]-selected survey list
- Short Name:
- J/AJ/123/1292
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The KPNO International Spectroscopic Survey (KISS) is an objective-prism survey for extragalactic emission-line objects. It combines many of the features of previous slitless spectroscopic surveys with the advantages of modern CCD detectors, and it is the first purely digital objective-prism survey for emission-line galaxies. Here we present the first list of emission-line galaxy candidates selected from our blue spectral data, which cover the wavelength range 4800-5500{AA}. In most cases, the detected emission line is [O III] {lambda}5007. The current survey list covers a 1{deg}-wide strip located at {delta}=29{deg}30' (B1950.0) and spanning the right ascension range 8h30min to 17h0min. An area of 116.6d{deg}^2^ is covered. A total of 223 candidate emission-line objects have been selected for inclusion in the survey list (1.91{deg}^-2^). We tabulate accurate coordinates and photometry for each source, as well as estimates of the redshift, emission-line flux, and equivalent width based on measurements of the digital objective-prism spectra. The median apparent magnitude of the sample is B=18.2, and galaxies with redshifts approaching z=0.1 are detected.
- ID:
- ivo://CDS.VizieR/J/ApJS/109/45
- Title:
- Kitt Peak galaxy redshift survey
- Short Name:
- J/ApJS/109/45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Redshifts, four-band photometry (U B_J_ R_F_ I_N_), and astrometry are presented for faint galaxies in four widely separated fields. We provide the necessary information to enable well-defined, statistically complete subsamples of faint galaxies to be constructed from the master catalog. The redshift survey is 86% and 71% complete to R_F_<=18.5 and R_F<=19, respectively, yielding 328 galaxies with reliable redshifts to R_F_<=19, with a median redshift of 0.142. Adding the galaxies from the fainter statistical sample yields a total of 583 reliable redshifts with a median redshift of 0.202. An additional 156 redshifts in the same fields, but not part of the samples defined here, are also given. Of the 739 galaxy redshifts presented, 212 are for galaxies with R_F_>20.