- ID:
- ivo://CDS.VizieR/J/ApJ/901/L8
- Title:
- Molecular gas properties of 70 PHANGS-ALMA galaxies
- Short Name:
- J/ApJ/901/L8
- Date:
- 23 Feb 2022 00:10:50
- Publisher:
- CDS
- Description:
- Using the PHANGS-ALMA CO(2-1) survey, we characterize molecular gas properties on ~100pc scales across 102,778 independent sightlines in 70 nearby galaxies. This yields the best synthetic view of molecular gas properties on cloud scales across the local star-forming galaxy population obtained to date. Consistent with previous studies, we observe a wide range of molecular gas surface densities (3.4dex), velocity dispersions (1.7dex), and turbulent pressures (6.5dex) across the galaxies in our sample. Under simplifying assumptions about subresolution gas structure, the inferred virial parameters suggest that the kinetic energy of the molecular gas typically exceeds its self-gravitational binding energy at ~100pc scales by a modest factor (1.3 on average). We find that the cloud-scale surface density, velocity dispersion, and turbulent pressure (1) increase toward the inner parts of galaxies, (2) are exceptionally high in the centers of barred galaxies (where the gas also appears less gravitationally bound), and (3) are moderately higher in spiral arms than in inter-arm regions. The galaxy-wide averages of these gas properties also correlate with the integrated stellar mass, star formation rate, and offset from the star-forming main sequence of the host galaxies. These correlations persist even when we exclude regions with extraordinary gas properties in galaxy centers, which contribute significantly to the inter-galaxy variations. Our results provide key empirical constraints on the physical link between molecular cloud populations and their galactic environment.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/892/148
- Title:
- Molecular ISM in nearby star-forming galaxies
- Short Name:
- J/ApJ/892/148
- Date:
- 19 Jan 2022 09:08:29
- Publisher:
- CDS
- Description:
- We compare the observed turbulent pressure in molecular gas, P_turb_, to the required pressure for the interstellar gas to stay in equilibrium in the gravitational potential of a galaxy, P_DE_. To do this, we combine arcsecond resolution CO data from PHANGS-ALMA with multiwavelength data that trace the atomic gas, stellar structure, and star formation rate (SFR) for 28 nearby star-forming galaxies. We find that P_turb_ correlates with--but almost always exceeds--the estimated P_DE_ on kiloparsec scales. This indicates that the molecular gas is overpressurized relative to the large-scale environment. We show that this overpressurization can be explained by the clumpy nature of molecular gas; a revised estimate of P_DE_ on cloud scales, which accounts for molecular gas self-gravity, external gravity, and ambient pressure, agrees well with the observed P_turb_ in galaxy disks. We also find that molecular gas with cloud-scale P_turb_~P_DE_>~10^5^k_B_Kcm^-3^ in our sample is more likely to be self-gravitating, whereas gas at lower pressure it appears more influenced by ambient pressure and/or external gravity. Furthermore, we show that the ratio between P_turb_ and the observed SFR surface density, {Sigma}_SFR_, is compatible with stellar feedback-driven momentum injection in most cases, while a subset of the regions may show evidence of turbulence driven by additional sources. The correlation between {Sigma}_SFR_ and kpc-scale P_DE_ in galaxy disks is consistent with the expectation from self-regulated star formation models. Finally, we confirm the empirical correlation between molecular-to-atomic gas ratio and kpc-scale P_DE_ reported in previous works.
- ID:
- ivo://CDS.VizieR/J/ApJ/851/76
- Title:
- Molecular transitions toward NGC5128 with ALMA
- Short Name:
- J/ApJ/851/76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Centaurus A, with its gas-rich elliptical host galaxy, NGC 5128, is the nearest radio galaxy at a distance of 3.8Mpc. Its proximity allows us to study the interaction among an active galactic nucleus, radio jets, and molecular gas in great detail. We present ALMA observations of low-J transitions of three CO isotopologues, HCN, HCO+, HNC, CN, and CCH toward the inner projected 500pc of NGC 5128. Our observations resolve physical sizes down to 40pc. By observing multiple chemical probes, we determine the physical and chemical conditions of the nuclear interstellar medium of NGC 5128. This region contains molecular arms associated with the dust lanes and a circumnuclear disk (CND) interior to the molecular arms. The CND is approximately 400pc by 200pc and appears to be chemically distinct from the molecular arms. It is dominated by dense gas tracers while the molecular arms are dominated by ^12^CO and its rare isotopologues. The CND has a higher temperature, elevated CN/HCN and HCN/HNC intensity ratios, and much weaker ^13^CO and C^18^O emission than the molecular arms. This suggests an influence from the AGN on the CND molecular gas. There is also absorption against the AGN with a low velocity complex near the systemic velocity and a high velocity complex shifted by about 60km/s. We find similar chemical properties between the CND in emission and both the low and high velocity absorption complexes, implying that both likely originate from the CND. If the HV complex does originate in the CND, then that gas would correspond to gas falling toward the supermassive black hole.
- ID:
- ivo://CDS.VizieR/J/A+A/369/57
- Title:
- Monitoring Mkn 279 in BVRI and H{beta} fluxes
- Short Name:
- J/A+A/369/57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Mid-infrared images of the Seyfert 1 galaxy Mrk 279 obtained with the ISO satellite are presented together with the results of a one-year monitoring campaign of the 2.5-11.7{mu}m spectrum. Contemporaneous optical photometric and spectrophotometric observations are also presented. The galaxy appears as a point-like source at the resolution of the ISOCAM instrument (4-5"). The 2.5-11.7{mu}m average spectrum of the nucleus in Mrk 279 shows a strong power law continuum with {alpha}=-0.80+/-0.05 (F_{nu}_{prop.to}{nu}^{alpha}^) and weak PAH emission features. The Mrk 279 spectral energy distribution shows a mid-IR bump, which extends from 2 to 15-20{mu}m. The mid-IR bump is consistent with thermal emission from dust grains at a distance of >100 light-days. No significant variations of the mid-IR flux have been detected during our observing campaign, consistent with the relatively low amplitude (~10% rms) of the optical variability during the campaign. The time delay for H{beta} line emission in response to the optical continuum variations is {tau}=16.7^+5.3^_-5.6_days, consistent with previous measurements.
- ID:
- ivo://CDS.VizieR/J/ApJ/873/117
- Title:
- Monitoring of the double quasar SDSS J1442+4055
- Short Name:
- J/ApJ/873/117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present r-band photometric monitoring of the two images, A and B, of the gravitationally lensed quasar SDSS J1442+4055 using the Liverpool Telescope (LT). From the LT light curves between 2015 December and 2018 August, we derive at once a time delay of 25.0+/-1.5d (1{sigma} confidence interval; A is leading) and microlensing magnification gradients below 10^-4^mag/d. The delay interval is not expected to be affected by an appreciable microlensing-induced bias, so it can be used to estimate cosmological parameters. This paper also focuses on new Gran Telescopio Canarias (GTC) and LT spectroscopic observations of the lens system. We determine the redshift of two bright galaxies around the doubly imaged quasar using LT spectroscopy, while GTC data lead to low-noise individual spectra of A, B, and the main lensing galaxy, G1. The G1 spectral shape is accurately matched to an early-type galaxy template at z=0.284, and it has potential for further relevant studies. Additionally, the quasar spectra show absorption by metal-rich gas at z~2. This dusty absorber is responsible for an extinction bump at a rest-frame wavelength of 2209+/-2{AA}, which has strengths of ~0.47 and 0.76mag/{mu}m for A and B, respectively. In such an intervening system, the dust-to-gas ratio, gas-phase metallicity indicator [Zn/H], and dust depletion level [Fe/Zn] are relatively high.
- ID:
- ivo://CDS.VizieR/J/A+A/609/A30
- Title:
- Monochromatic conversion factors to LIR & Mdust
- Short Name:
- J/A+A/609/A30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new, publicly available library of dust spectral energy distributions (SEDs). These SEDs are characterized by only three parameters: the dust mass (Mdust), the dust temperature (Tdust), and the mid-to-total infrared color (IR8=LIR/L8). The latter measures the relative contribution of polycyclic aromatic hydrocarbon (PAH) molecules to the total infrared luminosity. We used this library to model star-forming galaxies at 0.5<z<4 in the deep CANDELS fields, using both individual detections and stacks of Herschel and ALMA imaging, and extending this sample to z=0 using the Herschel Reference Survey. At first order, the dust SED of a galaxy was observed to be independent of stellar mass, but evolving with redshift. We found trends of increasing Tdust and IR8 with redshift and distance from the SFR-M* main sequence, and quantified for the first time their intrinsic scatter. Half of the observed variations of these parameters was captured by the above empirical relations, and after subtracting the measurement errors we found residual scatters of {delta}Tdust/Tdust=12% and {delta}logIR8=0.18dex. We observed second order variations with stellar mass: massive galaxies (M*>10^119M_{sun}_) at z<=1 have slightly lower temperatures indicative of a reduced star formation efficiency, while low mass galaxies (M*<10^10^M_{sun}_) at z>=1 showed reduced PAH emission, possibly linked to their lower metallicities. Building on these results, we constructed high-fidelity mock galaxy catalogs to predict the accuracy of infrared luminosities and dust masses determined using a single broadband measurement. Using a single James Webb Space Telescope (JWST) MIRI band, we found that LIR is typically uncertain by 0.15dex, with a maximum of 0.25dex when probing the rest-frame 8um, and this is not significantly impacted by typical redshift uncertainties. On the other hand, we found that ALMA bands 8 to 7 and 6 to 3 measured the dust mass at better than 0.2 and 0.15dex, respectively, and independently of redshift, while bands 9 to 6 only measured LIR at better than 0.2dex at z>1, 3.2, 3.8, and 5.7, respectively. Starburst galaxies had their LIR significantly underestimated when measured by a single JWST or ALMA band, while their dust mass from a single ALMA band were moderately overestimated. This dust library and the results of this paper can be used immediately to improve the design of observing proposals, and interpret more accurately the large amount of archival data from Spitzer, Herschel and ALMA.
- ID:
- ivo://CDS.VizieR/J/AJ/105/35
- Title:
- Montreal Blue Galaxy Survey
- Short Name:
- J/AJ/105/35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe and present the first results of a UV-bright galaxy survey using the Montreal-Cambridge-Tololo (MCT) plate collection. Visual inspection of 57 CTIO Curtis Schmidt plates, covering more than 1300 sq. deg., has resulted in the identification of 95 UV-bright galaxies brighter than B = 15.5. Even though 80% of these objects are IRAS sources, barely 20% have their nature already established. The initial result of our survey shows that the bulk of our UV-bright candidates are narrow emission-line galaxies commonly known as starburst or HII galaxies. The fraction of AGNs found is somewhat less than 10%, but comparable to what has been found by the Markarian survey. We expect to find approximately 500 UV-bright galaxies in the 7000 sq. deg. of The MCT Survey with b < -40 deg. As we go further south, a large number of bright new objects will be discovered.
- ID:
- ivo://CDS.VizieR/J/AJ/108/405
- Title:
- Montreal Blue Galaxy Survey. II.
- Short Name:
- J/AJ/108/405
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present and discuss the second list of the Montreal Blue Galaxy survey. Following the inspection of 71 plates, we found 237 new candidates with B<15.5. 73 percent of them are also detected by IRAS. Spectrophotometry was carried out, at medium resolution, for a subset of 40 objects leading to the identification of three new AGNs and producing 13 new radial velocities. Spectral classification of our candidates confirms our previous finding that the majority of our candidates are starburst nucleus galaxies similar to the objects studied by Balzano [1983ApJ...268..602B]. Our survey is biased against the high excitation starburst H II galaxies and the LINER galaxies. Metallicities of our galaxies are found to be from log(O/H)=8.4 to 9.0, which suggests galaxies in advanced stages of chemical evolution.
- ID:
- ivo://CDS.VizieR/J/MNRAS/355/82
- Title:
- Morphological analysis of HDF-N and HDF-S
- Short Name:
- J/MNRAS/355/82
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on drizzled F606W and F814W images, we present quantitative structural parameters in the V-band rest-frame for all galaxies with z<1 and I_814_(AB)<24.5mag in the Hubble Deep Fields North and South. Our structural parameters are based on a two-component surface brightness distribution using a Sersic bulge and an exponential disc. Detailed simulations and comparisons with previous work are presented.
- ID:
- ivo://CDS.VizieR/VII/62A
- Title:
- Morphological Cat. of Gal. (MCG)
- Short Name:
- VII/62A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog is a compilation of information for approximately 34000 galaxies found and examined on the Palomar Observatory Sky Survey (POSS). Individual identifiers are assigned for about 29000 galaxies and information on the remaining 5000 is present in the extensive notes of the published catalogs (Vorontsov-Velyaminov et al. 1962-1968). The catalog is structured according to the POSS zones, counting from the equator, and is numbered from +15 (corresponding to +90 deg) to +01 (+06 zone) and +00 (equatorial zone) to -05 (-30 zone); the fields are numbered with increasing right ascension. The catalog includes cross-identifications to the NGC (Dreyer 1888) and IC (Dreyer 1895, 1908) catalogs, equatorial coordinates for B1950.0, magnitudes, estimated sizes and intensities of the brighter inner region and the entire object, and estimated inclinations.
