- ID:
- ivo://CDS.VizieR/J/MNRAS/445/881
- Title:
- LVL global optical photometry
- Short Name:
- J/MNRAS/445/881
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the global optical photometry of 246 galaxies in the Local Volume Legacy (LVL) survey. The full volume-limited sample consists of 258 nearby (D<11Mpc) galaxies whose absolute B-band magnitude span a range of -9.6<M_B_<-20.7mag. A composite optical (UBVR) data set is constructed from observed UBVR and Sloan Digital Sky Survey ugriz imaging, where the ugriz magnitudes are transformed into UBVR. We present photometry within three galaxy apertures defined at UV, optical, and IR wavelengths. Flux comparisons between these apertures reveal that the traditional optical R25 galaxy apertures do not fully encompass extended sources. Using the larger IR apertures, we find colour-colour relationships where later type spiral and irregular galaxies tend to be bluer than earlier type galaxies. These data provide the missing optical emission from which future LVL studies can construct the full panchromatic (UV-optical-IR) spectral energy distributions.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/696/546
- Title:
- Ly{alpha} emitters at z~4.86
- Short Name:
- J/ApJ/696/546
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a survey for Ly{alpha} emitters at z~4.86 based on optical narrowband ({lambda}c=7126{AA}, {Delta}{lambda}=73{AA}) and broadband (B, V, r', i', and z') observations of the Cosmic Evolution Survey field using Suprime-Cam on the Subaru Telescope. We find 79 Ly{alpha} emitter (LAE) candidates at z~4.86 over a contiguous survey area of 1.83deg^2^, down to the Ly{alpha} line flux of 1.47x10^-17^erg/s/cm^2^. We obtain the Ly{alpha} luminosity function with a best-fit Schechter parameters of log L*=42.9^+0.5^_-0.3_erg/s and {Phi}*=1.2^+8.0^_-1.1_x10^-4^Mpc^-3^ for {alpha}=-1.5 (fixed). The two-point correlation function for our LAE sample is {xi}(r)=(r/4.4^+5.7^_-2.9_Mpc)^-1.90+/-0.22^. In order to investigate the field-to-field variations of the properties of Ly{alpha} emitters, we divide the survey area into nine tiles of 0.5x0.5{deg} each. We find that the number density varies with a factor of ~2 from field to field with high statistical significance. However, we find no significant field-to-field variance when we divide the field into four tiles with 0.7x0.7{deg} each. We conclude that at least 0.5deg^2^ survey area is required to derive averaged properties of LAEs at z~5, and our survey field is wide enough to overcome the cosmic variance.
- ID:
- ivo://CDS.VizieR/J/ApJ/736/48
- Title:
- 48 Lyman break galaxies at z~3 in HUDF
- Short Name:
- J/ApJ/736/48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present evidence for spatially extended low surface brightness emission around Lyman break galaxies (LBGs) in the V-band image of the Hubble Ultra Deep Field, corresponding to the z~3 rest-frame far-UV (FUV) light, which is a sensitive measure of star formation rates (SFRs). We find that the covering fraction of molecular gas at z~3 is not adequate to explain the emission in the outskirts of LBGs, while the covering fraction of neutral atomic-dominated hydrogen gas at high redshift is sufficient. We develop a theoretical framework to connect this emission around LBGs to the expected emission from neutral HI gas, i.e., damped Ly{alpha} systems (DLAs), using the Kennicutt-Schmidt (KS) relation. Working under the hypothesis that the observed FUV emission in the outskirts of LBGs is from in situ star formation in atomic-dominated hydrogen gas, the results suggest that the SFR efficiency in such gas at z~3 is between factors of 10 and 50 lower than predictions based on the local KS relation. The total SFR density in atomic-dominated gas at z~3 is constrained to be ~10% of that observed from the inner regions of LBGs. In addition, the metals produced by in situ star formation in the outskirts of LBGs yield metallicities comparable to those of DLAs, which is a possible solution to the "Missing Metals" problem for DLAs. Finally, the atomic-dominated gas in the outskirts of galaxies at both high and low redshifts has similar reduced SFR efficiencies and is consistent with the same power law.
- ID:
- ivo://CDS.VizieR/J/MNRAS/465/316
- Title:
- Lyman continuum LAEs and LBGs in SSA22 field
- Short Name:
- J/MNRAS/465/316
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the largest to date sample of hydrogen Lyman continuum (LyC) emitting galaxy candidates at any redshift, with 18 Lyman {alpha} emitters (LAEs) and seven Lyman break galaxies (LBGs), obtained from the SSA22 field with Subaru/Suprime-Cam. The sample is based on the 159 LAEs and 136 LBGs observed in the field, all with spectroscopically confirmed redshifts, and these LyC candidates are selected as galaxies with counterparts in a narrow-band filter image which traces LyC at z>=3.06. Many LyC candidates show a spatial offset between the rest-frame non-ionizing ultraviolet (UV) detection and the LyC-emitting substructure or between the Ly{alpha} emission and LyC. The possibility of foreground contamination complicates the analysis of the nature of LyC emitters, although statistically it is highly unlikely that all candidates in our sample are contaminated by foreground sources. Many viable LyC LAE candidates have flux density ratios inconsistent with standard models, while also having too blue UV slopes to be foreground contaminants. Stacking reveals no significant LyC detection, suggesting that there is a dearth of objects with marginal LyC signal strength, perhaps due to a bimodality in the LyC emission. The foreground contamination corrected 3{sigma} upper limits of the observed average flux density ratios are fLyC/fUV < 0.08 from stacking LAEs and f_LyC_/f_UV_<0.02 from stacking LBGs. There is a sign of a positive correlation between LyC and Ly{alpha}, suggesting that both types of photons escape via a similar mechanism. The LyC detection rate among protocluster LBGs is seemingly lower compared to the field.
- ID:
- ivo://CDS.VizieR/J/MNRAS/465/302
- Title:
- Lyman continuum leaking AGN in SSA22 field
- Short Name:
- J/MNRAS/465/302
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Subaru/SuprimeCam narrow-band photometry of the SSA22 field reveals the presence of four Lyman continuum (LyC) candidates among a sample of 14 active galactic nuclei (AGNs). Two show offsets and likely have stellar LyCin nature or are foreground contaminants. The remaining two LyC candidates are type I AGN. We argue that the average LyC escape fraction of high-redshift, low-luminosity AGN is not likely to be unity, as often assumed in the literature. From direct measurement we obtain the average LyC-to-UV flux density ratio and ionizing emissivity for a number of AGN classes and find it at least a factor of 2 lower than values obtained assuming f_esc_=1. Comparing to recent Ly{alpha} forest measurements, AGNs at redshift z~3 make up at most ~12 per cent and as little as ~5 per cent of the total ionizing budget. Our results suggest that AGNs are unlikely to dominate the ionization budget of the Universe at high redshifts.
- ID:
- ivo://CDS.VizieR/J/AJ/134/1963
- Title:
- MACHO r,b light curves of MC eclipsing binaries
- Short Name:
- J/AJ/134/1963
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new sample of 4634 eclipsing binary stars in the Large Magellanic Cloud (LMC), expanding on a previous sample of 611 objects and a new sample of 1509 eclipsing binary stars in the Small Magellanic Cloud (SMC), that were identified in the light-curve database of the MACHO project. We perform a cross-correlation with the OGLE-II LMC sample, finding 1236 matches. A cross correlation with the OGLE-II SMC sample finds 698 matches. We then compare the LMC subsamples corresponding to the center and periphery of the LMC and find only minor differences between the two populations. These samples are sufficiently large and complete that statistical studies of the binary star populations are possible.
- ID:
- ivo://CDS.VizieR/J/AJ/115/1894
- Title:
- M31A eclipsing binaries and Cepheids
- Short Name:
- J/AJ/115/1894
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have undertaken a long-term project, DIRECT, to obtain the direct distances to two important galaxies in the cosmological distance ladder, M31 and M33, using detached eclipsing binaries (DEBs) and Cepheids. While rare and difficult to detect, DEBs provide us with the potential to determine these distances with an accuracy better than 5%. The extensive photometry obtained in order to detect DEBs provides us with good light curves for the Cepheid variables. These are essential to the parallel project to derive direct Baade-Wesselink distances to Cepheids in M31 and M33. For both Cepheids and eclipsing binaries, the distance estimates will be free of any intermediate steps. As a first step in the DIRECT project, between 1996 September and 1997 January we obtained 36 full nights on the Michigan-Dartmouth-MIT Observatory 1.3m telescope and 45 full/partial nights on the F. L. Whipple Observatory 1.2m telescope to search for DEBs and new Cepheids in the M31 and M33 galaxies. In this paper, second in a series, we present the catalog of variable stars, most of them newly detected, found in the field M31A [({alpha},{delta})=(11.34{deg}, 41.73{deg}), J2000.0]. We have found 75 variable stars: 15 eclipsing binaries, 43 Cepheids, and 17 other periodic, possible long-period or nonperiodic variables. The catalog of variables, as well as their photometry and finding charts, is available via anonymous ftp and the World Wide Web. The CCD frames are available upon request.
- ID:
- ivo://CDS.VizieR/J/AJ/128/1606
- Title:
- Magellanic Clouds Photometric Survey: the LMC
- Short Name:
- J/AJ/128/1606
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present our catalog of U, B, V, and I stellar photometry of the central 64deg^2^ area of the Large Magellanic Cloud. Internal and external astrometric and photometric tests using existing optical photometry (U, B, and V from Massey's bright star catalog (Cat. <II/236>) and I from the near-infrared sky survey DENIS) are used to confirm our observational uncertainty estimates. We fit stellar atmosphere models to the optical data to check the consistency of the photometry for individual stars across the passbands and to estimate the line-of-sight extinction. Finally, we use the estimated line-of-sight extinctions to produce an extinction map across the Large Magellanic Cloud, confirm the variation of extinction as a function of stellar population, and produce a simple geometric model for the extinction as a function of stellar population.
- ID:
- ivo://CDS.VizieR/J/AJ/123/855
- Title:
- Magellanic Clouds Photometric Survey: the SMC
- Short Name:
- J/AJ/123/855
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present our catalog of U, B, V, and I stellar photometry of the central 18{deg}^2^ area of the Small Magellanic Cloud. We combine our data with the Two Micron All Sky Survey (2MASS) and Deep Near-Infrared Southern Sky Survey (DENIS) catalogs to provide, when available, U through K_s_ data for stars. Internal and external astrometric and photometric tests using existing optical photometry (U, B, and V from Massey's (ApJS, in press) bright star catalog; B, V, and I from the microlensing database of OGLE; and I from the near-infrared sky survey DENIS) are used to determine the observational uncertainties and identify systematic errors. We fit stellar atmosphere models to the optical data to check the consistency of the photometry for individual stars across the passbands and to estimate the line-of-sight extinction. Finally, we use the estimated line-of-sight extinctions to produce an extinction map across the Small Magellanic Cloud, and we investigate the nature of extinction as a function of stellar population.
- ID:
- ivo://CDS.VizieR/J/ApJ/819/53
- Title:
- Magellan/M2FS spectroscopy of Tucana 2 and Grus 1
- Short Name:
- J/ApJ/819/53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from spectroscopic observations with the Michigan/Magellan Fiber System (M2FS) of 147 stellar targets along the line of sight to the newly discovered "ultrafaint" stellar systems Tucana 2 (Tuc 2) and Grus 1 (Gru 1). Based on simultaneous estimates of line of sight velocity and stellar-atmospheric parameters, we identify 8 and 7 stars as probable members of Tuc 2 and and Gru 1, respectively. Our sample for Tuc 2 is sufficient to resolve an internal velocity dispersion of 8.6^+4.4^_-2.7_km/s about a mean of -129.1+/-3.5km/s (solar rest frame), and to estimate a mean metallicity of [Fe/H]=-2.23^+0.18^_-0.12_. These results place Tuc 2 on chemodynamical scaling relations followed by dwarf galaxies, suggesting a dominant dark matter component with dynamical mass 2.7^+3.1^_-1.3_x10^6^M_{sun}_ enclosed within the central ~160pc, and dynamical mass-to-light ratio 1913^+2234^_-950_M_{sun}_/L_{nu},{sun}_. For Gru 1 we estimate a mean velocity of -140.5^+2.4^_-1.6_km/s and a mean metallicity of [Fe/H]=-1.42^+0.55^_-0.42_ but our sample does not resolve Gru 1's velocity dispersion. The radial coordinates of Tuc 2 and Gru 1 in Galactic phase space suggest that their orbits are among the most energetic within a distance of <~300pc. Moreover, their proximity to each other in this space arises naturally if both objects are trailing the Large Magellanic Cloud.
