The ALMaQUEST survey – III. Scatter in the resolved star-forming main sequence is primarily due to variations in star formation efficiency

Using a sample of 11,478 spaxels in 34 galaxies with molecular gas, star formation and stellar maps taken from the ALMA-MaNGA QUEnching and STar formation (ALMaQUEST) survey, we investigate the parameters that correlate with variations in star formation rates on kpc scales. We use a combination of correlation statistics and an artificial neural network to quantify the parameters that drive both the absolute star formation rate surface density (Sigma_SFR), as well as its scatter around the resolved star forming main sequence (Delta Sigma_SFR). We find that Sigma_SFR is primarily regulated by molecular gas surface density (Sigma_H2) with a secondary dependence on stellar mass surface density (Sigma_*), as expected from an `extended Kennicutt-Schmidt relation'. However, Delta Sigma_SFR is driven primarily by changes in star formation efficiency (SFE), with variations in gas fraction playing a secondary role. Taken together, our results demonstrate that whilst the absolute rate of star formation is primarily set by the amount of molecular gas, the variation of star formation rate above and below the resolved star forming main sequence (on kpc scales) is primarily due to changes in SFE

1862-12-13 List of casualties in the 2nd Maine Regiment at the Battle of Fredericksburg

https://digitalmaine.com/cw_me_2nd_regiment_corr/1422/thumbnail.jp

1863-02-24 Lieutenant Colonel D.F. Sargent verifies commission of Lieutenant Sewall H. Downs

https://digitalmaine.com/cw_me_2nd_regiment_corr/1495/thumbnail.jp

COLDz: Karl G. Jansky Very Large Array discovery of a gas-rich galaxy in COSMOS

The broad spectral bandwidth at mm and cm-wavelengths provided by the recent upgrades to the Karl G. Jansky Very Large Array (VLA) has made it possible to conduct unbiased searches for molecular CO line emission at redshifts, z > 1.31. We present the discovery of a gas-rich, star-forming galaxy at z = 2.48, through the detection of CO(1-0) line emission in the COLDz survey, through a sensitive, Ka-band (31 to 39 GHz) VLA survey of a 6.5 square arcminute region of the COSMOS field. We argue that the broad line (FWHM ~570 +/- 80 km/s) is most likely to be CO(1-0) at z=2.48, as the integrated emission is spatially coincident with an infrared-detected galaxy with a photometric redshift estimate of z = 3.2 +/- 0.4. The CO(1-0) line luminosity is L'_CO = (2.2 +/- 0.3) x 10^{10} K km/s pc^2, suggesting a cold molecular gas mass of M_gas ~ (2 - 8)x10^{10}M_solar depending on the assumed value of the molecular gas mass to CO luminosity ratio alpha_CO. The estimated infrared luminosity from the (rest-frame) far-infrared spectral energy distribution (SED) is L_IR = 2.5x10^{12} L_solar and the star-formation rate is ~250 M_solar/yr, with the SED shape indicating substantial dust obscuration of the stellar light. The infrared to CO line luminosity ratio is ~114+/-19 L_solar/(K km/s pc^2), similar to galaxies with similar SFRs selected at UV/optical to radio wavelengths. This discovery confirms the potential for molecular emission line surveys as a route to study populations of gas-rich galaxies in the future

Exposure to Smoking Imagery in Popular Films and Adolescent Smoking in Mexico

Background: Exposure to smoking imagery in films in consistently associated with smoking behavior and its psychological antecedents among adolescents in high-income countries, but its association with adolescent smoking in middle-income countries is unknown. Methods: In 2006, a cross-sectional sample of 3876 Mexican adolescents in secondary school was surveyed on smoking behavior, smoking risk factors, and exposure to 42 popular films that contained smoking. Participants were classified into quartiles of exposure to smoking imagery across all films they reported having seen. Models were estimated to determine associations among quartiles of film-smoking exposure, smoking behavior, and the psychological antecedents of smoking, adjusting for age, gender, sensation seeking, self-esteem, parental smoking, sibling smoking, best-friend smoking, having a bedroom TV, and private versus public school attendance. Analyses were conducted in 2007. Results: Adolescents were exposed to an average of 51.7 (SE=1.3) minutes of smoking in the films they viewed. Crude and adjusting ORs indicated positive associations between quartiles of film-smoking exposure and both current smoking (AOR4v1=3.13; p\u3c0.0001) and having ever smoked (AOR4v1=2.42;p\u3c0.0001). Data from never-smokers (n=2098) were analyzed to determine associations between film-smoking exposure and psychological antecedents of smoking uptake. Crude and adjusted coefficients indicated significant, positive associations between exposure and susceptibility to smoking (AOR4v1=1.66; p\u3c0.05); favorable attitudes toward smoking (Adjusted B4v1=0.44;p\u3c0.0001); and perceived peer prevalence of smoking (Adjusted B4v1=0.26; p\u3c0.0001). Conclusions: Exposure to smoking in films appears associated with smoking among Mexican adolescents. Policies could aim to decrease youth exposure to smoking in nationally and internationally distributed

A molecular line scan in the Hubble Deep Field North

We present a molecular line scan in the Hubble Deep Field North (HDF-N) that covers the entire 3mm window (79-115 GHz) using the IRAM Plateau de Bure Interferometer. Our CO redshift coverage spans z2. We reach a CO detection limit that is deep enough to detect essentially all z>1 CO lines reported in the literature so far. We have developed and applied different line searching algorithms, resulting in the discovery of 17 line candidates. We estimate that the rate of false positive line detections is ~2/17. We identify optical/NIR counterparts from the deep ancillary database of the HDF-N for seven of these candidates and investigate their available SEDs. Two secure CO detections in our scan are identified with star-forming galaxies at z=1.784 and at z=2.047. These galaxies have colors consistent with the `BzK' color selection and they show relatively bright CO emission compared with galaxies of similar dust continuum luminosity. We also detect two spectral lines in the submillimeter galaxy HDF850.1 at z=5.183. We consider an additional 9 line candidates as high quality. Our observations also provide a deep 3mm continuum map (1-sigma noise level = 8.6 μJy/beam). Via a stacking approach, we find that optical/MIR bright galaxies contribute only to <50% of the SFR density at 1<z<3, unless high dust temperatures are invoked. The present study represents a first, fundamental step towards an unbiased census of molecular gas in `normal' galaxies at high-z, a crucial goal of extragalactic astronomy in the ALMA era