- ID:
- ivo://CDS.VizieR/J/ApJ/712/585
- Title:
- Apparent velocity measurements of DA WDs
- Short Name:
- J/ApJ/712/585
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We measure apparent velocities (v_app_) of the H{alpha} and H{beta} Balmer line cores for 449 non-binary thin disk normal DA white dwarfs (WDs) using optical spectra taken for the European Southern Observatory SN Ia progenitor survey (SPY). Assuming these WDs are nearby and comoving, we correct our velocities to the local standard of rest so that the remaining stellar motions are random. By averaging over the sample, we are left with the mean gravitational redshift, <v_g_>: we find <v_g_>=<v_app_>=32.57+/-1.17km/s. Using the mass-radius relation from evolutionary models, this translates to a mean mass of 0.647^+0.013^_-0.014_M_{sun}_. We interpret this as the mean mass for all DAs.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/645/A19
- Title:
- Arcturus Lab (line list)
- Short Name:
- J/A+A/645/A19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-resolution spectroscopy in the near infrared (NIR) is a powerful tool to characterise the physical and chemical properties of cool star atmospheres. The current generation of NIR echelle spectrographs enables the sampling of many spectral features over the full 0.9-2.4um range for a detailed chemical tagging. Within the Stellar Population Astrophysics Large Program at the TNG, we used a high-resolution (R=50000) NIR spectrum of Arcturus acquired with the GIANO-B echelle spectrograph as a laboratory to define and calibrate an optimal line list and new diagnostic tools to derive accurate stellar parameters and chemical abundances. We inspected several hundreds of NIR atomic and molecular lines to derive abundances of 26 different chemical species, including CNO, iron-group, alpha, Z-odd and neutron-capture elements. We then performed a similar analysis in the optical using Arcturus VLT-UVES spectra. By the combined NIR and optical analysis we defined a new thermometer and a new gravitometer for giant stars, based on the comparison of Carbon and Oxygen abundances, respectively, as derived from atomic and molecular lines. We then derived self-consistent stellar parameters and chemical abundances of Arcturus over the full 4800-24500{AA} spectral range and we compared them with previous studies in the literature. We finally discussed a number of problematic lines, which can be affected by deviations from thermal equilibrium and/or chromospheric activity, as traced by the observed variability of HeI at 10830{AA}.
- ID:
- ivo://CDS.VizieR/J/AJ/132/1851
- Title:
- Arecibo obs. of formaldehyde in L1551
- Short Name:
- J/AJ/132/1851
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report observations of the formaldehyde (H_2_CO) 6cm (4.8GHz) line toward L1551. The observations were conducted with the Arecibo Telescope (beam FWHP~1') to verify the tentative detection of H_2_CO thermal emission reported by Duncan and collaborators in 1987MNRAS.224..721D. The H_2_CO emission lines were expected to be present with a signal-to-noise ratio of >~10 in our spectra. However, we did not detect H_2_CO emission; i.e., our data rule out their tentative detection. The absence of H_2_CO emission is also confirmed by the fact that the H_2_CO line profiles at the two positions of expected emission are well fitted by a single absorption component (accounting for the hyperfine structure of the line) in one of the positions and by a single absorption line plus a red-wing absorption component in the second position. The Orion BN/KL region remains the only H_2_CO 6cm thermal emitter known. Our observations also demonstrate that the H_2_CO 6cm absorption line traces not only the quiescent molecular cloud but also the kinematics associated with the star formation process in L1551-IRS5.
- ID:
- ivo://CDS.VizieR/J/ApJ/871/129
- Title:
- A redshift catalog of the galaxy cluster A2029
- Short Name:
- J/ApJ/871/129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the structure of galaxy cluster A2029 and its surroundings based on intensive spectroscopy along with X-ray and weak lensing observations. The redshift survey includes 4376 galaxies (1215 spectroscopic cluster members) within 40' of the cluster center; the redshifts are included here. Two subsystems, A2033 and a southern infalling group (SIG), appear in the infall region based on the spectroscopy, as well as on the weak lensing and X-ray maps. The complete redshift survey of A2029 also identifies at least 12 foreground and background systems (10 are extended X-ray sources) in the A2029 field; we include a census of their properties. The X-ray luminosities (L_X_)-velocity dispersions ({sigma}_cl_) scaling relations for A2029, A2033, SIG, and the foreground/background systems are consistent with the known cluster scaling relations. The combined spectroscopy, weak lensing, and X-ray observations provide a robust measure of the masses of A2029, A2033, and SIG. The total mass of the infalling groups (A2033 and SIG) is ~60% of the M200 of the primary cluster, A2029. Simple dynamical considerations suggest that A2029 will accrete these subsystems in the next few Gyr. In agreement with simulations and other clusters observed in a similar redshift range, the total mass in the A2029 infall region is comparable to the A2029 M200 and will mostly be accreted in the long-term future.
- ID:
- ivo://CDS.VizieR/J/ApJ/842/88
- Title:
- A redshift survey of the central region of A2199
- Short Name:
- J/ApJ/842/88
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results from an extensive spectroscopic survey of the central region of the nearby galaxy cluster Abell 2199 (A2199) at z=0.03. By combining 775 new redshifts from the MMT/Hectospec observations with the data in the literature, we construct a large sample of 1624 galaxies with measured redshifts at R<30', which results in high spectroscopic completeness at r_petro,0_<20.5 (77%). We use these data to study the kinematics and clustering of galaxies, focusing on the comparison with those of the intracluster medium (ICM) from Suzaku X-ray observations. We identify 406 member galaxies of A2199 at R<30' using the caustic technique. The velocity dispersion profile of cluster members appears smoothly connected to the stellar velocity dispersion profile of the cD galaxy. The luminosity function is well fitted with a Schechter function at M_r_< -15. The radial velocities of cluster galaxies generally agree well with those of the ICM, but there are some regions where the velocity difference between the two is about a few hundred kilometers per second. The cluster galaxies show a hint of global rotation at R<5' with v_rot_=300-600km/s, but the ICM in the same region does not show such rotation. We apply a friends-of-friends algorithm to the cluster galaxy sample at R<60' and identify 32 group candidates, and examine the spatial correlation between the galaxy groups and X-ray emission. This extensive survey in the central region of A2199 provides an important basis for future studies of interplay among the galaxies, the ICM, and the dark matter in the cluster.
- ID:
- ivo://CDS.VizieR/J/A+A/592/A21
- Title:
- Are infrared dark clouds really quiescent?
- Short Name:
- J/A+A/592/A21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The dense, cold regions where high-mass stars form are poorly characterised, yet they represent an ideal opportunity to learn more about the initial conditions of high-mass star formation (HMSF), since high-mass starless cores (HMSCs) lack the violent feedback seen at later evolutionary stages. We present continuum maps obtained from the Submillimeter Array (SMA) interferometry at 1.1mm for four infrared dark clouds (IRDCs, G28.34S, IRDC 18530, IRDC 18306, and IRDC 18308). We also present 1mm/3mm line surveys using IRAM 30m single-dish observations. Our results are: (1) At a spatial resolution of 10^4^AU, the 1.1mm SMA observations resolve each source into several fragments. The mass of each fragment is on average >10M_{sun}_, which exceeds the predicted thermal Jeans mass of the whole clump by a factor of up to 60, indicating that thermal pressure does not dominate the fragmentation process. Our measured velocity dispersions in the 30m lines imply that non-thermal motions provides the extra support against gravity in the fragments. (2) Both non-detection of high-J transitions and the hyperfine multiplet fit of N_2_H^+^(1-0), C_2_H(1-0), HCN(1-0), and H^13^CN(1-0) indicate that our sources are cold and young. However, obvious detection of SiO and the asymmetric line profile of HCO^+^(1-0) in G28.34S indicate a potential protostellar object and probable infall motion. (3) With a large number of N-bearing species, the existence of carbon rings and molecular ions, and the anti-correlated spatial distributions between N_2_H^+^/NH_2_D and CO, our large-scale high-mass clumps exhibit similar chemical features as small-scale low-mass prestellar objects. This study of a small sample of IRDCs illustrates that thermal Jeans instability alone cannot explain the fragmentation of the clump into cold (~15K), dense (>10^5^cm^-3^) cores and that these IRDCs are not completely quiescent.
- ID:
- ivo://CDS.VizieR/J/A+A/643/A91
- Title:
- ArH+ and p-H2O+ spectra towards 7 molecular clouds
- Short Name:
- J/A+A/643/A91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- One of the surprises of the Herschel mission was the detection of ArH+, toward the Crab Nebula in emission and in absorption toward strong Galactic background sources. Although, these detections were limited to the first quadrant of the Galaxy, the existing data suggests that ArH+ ubiquitously and exclusively probes the diffuse atomic regions of the interstellar medium. In this study we extend the coverage of ArH+ to other parts of the Galaxy with new observations of its J=1-0 transition along seven Galactic sight lines toward bright sub-millimetre continuum sources. We aim to benchmark its efficiency as a tracer of purely atomic gas by evaluating its correlation (or lack of correlation as suggested by chemical models) with other well known atomic gas tracers like OH+ and H_2_O+ and the molecular gas tracer CH. The observations of the J=1-0 line of ArH+ near 617.5GHz were made feasible with the new, sensitive SEPIA660 receiver on the APEX 12m telescope. Further, the two sidebands of this receiver allowed us to observe the N_KaKc_=1_1,0_-1_0,1_ transitions of para-H_2_O+ at 607.227GHz simultaneously with the ArH+ line. We model the optically thin absorption spectra of the different species and subsequently derived their column densities. By analysing the steady state chemistry of OH+ and o-H_2_O+ we derive on average a cosmic-ray ionisation rate of 2.3+/-0.3x10^-16^s^-1^, toward the sightlines studied in this work. Using the derived values of the cosmic-ray ionisation rates and the observed ArH+ abundances we constrain the molecular fraction of the gas traced by ArH+ to lie below 2x10^-2^ with a median value of 8.8x10^-4^. Combined, our observations of ArH+, OH+, H_2_O+ and CH probe different regimes of the interstellar medium, from diffuse atomic to diffuse and translucent molecular clouds. Over Galactic scales, we see that the distribution of N(ArH+) is associated with that of N(H), particularly in the inner Galaxy (within 7 kpc of the Galactic center) with potentially even contributions from the warm neutral medium phase of atomic gas at larger galactocentric distances. We derive an average ortho-to-para ratio for H_2_O+ of 2.1+/-1.0, which corresponds to a nuclear spin temperature of 41K, consistent with the typical gas temperatures of diffuse clouds.
- ID:
- ivo://CDS.VizieR/J/A+A/559/A10
- Title:
- Arp 102B spectral optical monitoring
- Short Name:
- J/A+A/559/A10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of long-term (1987-2010) optical spectral monitoring of the broad-line radio galaxy Arp 102B, a prototype of an active galactic nucleus with double-peaked broad emission lines that are commonly assumed to be emitted from an accretion disk. To explore the structure of the broad-line region (BLR), we analyze the light-curves of the broad H{alpha} and H{beta} lines and the continuum flux. We aim to estimate the dimensions of the broad-line emitting regions and the mass of the central black hole. We used the cross correlation function to find lags between the lines and continuum variations. We investigated the correlation between line and continuum fluxes in more detail, and explored periodical variations of the red-to-blue line flux ratio using Lomb-Scargle periodograms.
- ID:
- ivo://CDS.VizieR/J/A+A/613/A72
- Title:
- AS1063 and MACS1206-08 datacubes
- Short Name:
- J/A+A/613/A72
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from the KMOS LENsing Survey (KLENS), which is exploiting gravitational lensing to study the kinematics of 24 star-forming galaxies at 1.4<z<3.5 with a median mass of log(M*/M_{sun}_)=9.6 and a median star formation rate (SFR) of 7.5M_{sun}/yr. We find that 25% of these low mass/low SFR galaxies are rotation-dominated, while the majority of our sample shows no velocity gradient. When combining our data with other surveys, we find that the fraction of rotation-dominated galaxies increases with the stellar mass, and decreases for galaxies with a positive offset from the main sequence (higher specific star formation rate). We also investigate the evolution of the intrinsic velocity dispersion, sigma_0_, as a function of the redshift, z, and stellar mass, M*, assuming galaxies in quasi-equilibrium (Toomre Q parameter equal to 1). From the z-sigma_0_ relation, we find that the redshift evolution of the velocity dispersion is mostly expected for massive galaxies (log(M*/M_{sun}_)>10). We derive a M*-sigma_0_ relation, using the Tully-Fisher relation, which highlights that a different evolution of the velocity dispersion is expected depending on the stellar mass, with lower velocity dispersions for lower masses, and an increase for higher masses, stronger at higher redshift. The observed velocity dispersions from this work and from comparison samples spanning 0<z<3.5 appear to follow this relation, except at higher redshift (z>2), where we observe higher velocity dispersions for low masses (log(M*/M_{sun}_)~9.6) and lower velocity dispersions for high masses (log(M*/M_{sun}_)~10.9) than expected. This discrepancy could, for instance, suggest that galaxies at high redshift do not satisfy the stability criterion, or that the adopted parametrization of the specific star formation rate and molecular properties fail at high redshift.
- ID:
- ivo://CDS.VizieR/J/ApJ/777/64
- Title:
- A search for double-peaked AGNs in AGES
- Short Name:
- J/ApJ/777/64
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dual supermassive black holes (SMBHs) with kiloparsec-scale separations in merger-remnant galaxies are informative tracers of galaxy evolution, but the avenue for identifying them in large numbers for such studies is not yet clear. One promising approach is to target spectroscopic signatures of systems where both SMBHs are fueled as dual active galactic nuclei (AGNs), or where one SMBH is fueled as an offset AGN. Dual AGNs may produce double-peaked narrow AGN emission lines, while offset AGNs may produce single-peaked narrow AGN emission lines with line-of-sight velocity offsets relative to the host galaxy. We search for such dual and offset systems among 173 Type 2 AGNs at z<0.37 in the AGN and Galaxy Evolution Survey (AGES), and we find two double-peaked AGNs and five offset AGN candidates. When we compare these results to a similar search of the DEEP2 Galaxy Redshift Survey and match the two samples in color, absolute magnitude, and minimum velocity offset, we find that the fraction of AGNs that are dual SMBH candidates increases from z=0.25 to z=0.7 by a factor of ~6 (from 2/70 to 16/91, or 2.9_-1.9_^+3.6^% to 18_-5_^+5^%). This may be associated with the rise in the galaxy merger fraction over the same cosmic time. As further evidence for a link with galaxy mergers, the AGES offset and dual AGN candidates are tentatively ~3 times more likely than the overall AGN population to reside in a host galaxy that has a companion galaxy (from 16/173 to 2/7, or 9_-2_^+3^% to 29_-19_^+26^%). Follow-up observations of the seven offset and dual AGN candidates in AGES will definitively distinguish velocity offsets produced by dual SMBHs from those produced by narrow-line region kinematics, and will help sharpen our observational approach to detecting dual SMBHs.
