507 research outputs found
Molecular gas in super spiral galaxies
We thank the referee for the careful revision of the manuscript and constructive comments. UL acknowledges support by the research projects AYA2017-84897-P and PID2020-114414GB-I00 from the Spanish Ministerio de EconomĂa y Competitividad, from the European Regional Development Funds (FEDER) and the Junta de AndalucĂa (Spain) grants FQM108. This work is based on observations carried out under project numbers 205-19 and 068-20 with the IRAM 30m telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain). This research made use of the âK-corrections calculatorâ service available at http://kcor.sai.msu.ru/ . This research made use of Astropy, a community- developed core Python ( http://www.python.org ) package for Astronomy (Astropy Collaboration 2013, 2018); ipython (PĂ©rez & Granger 2007); matplotlib (Hunter 2007); SciPy, a collection of open source software for scientific computing in Python (Virtanen et al. 2020); and NumPy, a structure for efficient numerical computation (van der Walt et al. 2011). This publication makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. This work was made possible by the NASA/IPAC Extragalactic Database and the NASA/ IPAC Infrared Science Archive, which are both operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. We acknowledge the usage of the HyperLeda database ( http://leda.univ-lyon1.fr ).At the highest stellar masses (log(M*) âł 11.5 Mâ), only a small fraction of galaxies are disk-like and actively star-forming objects. These so-called âsuper spiralsâ are ideal objects to better understand how galaxy evolution proceeds and to extend our knowledge about the relation between stars and gas to a higher stellar mass regime. We present new CO(1â0) data for a sample of 46 super spirals and for 18 slightly lower-mass (log(M*) > 11.0 Mâ) galaxies with broad HI lines â HI fast-rotators (HI-FRs). We analyze their molecular gas mass, derived from CO(1â0), in relation to their star formation rate (SFR) and stellar mass, and compare the results to values and scaling relations derived from lower-mass galaxies. We confirm that super spirals follow the same star-forming main sequence (SFMS) as lower-mass galaxies. We find that they possess abundant molecular gas (mean redshift-corrected molecular gas mass fraction (log(fmol,âzcorr) = â1.36 ± 0.02), which lies above the extrapolation of the scaling relation with stellar mass derived from lower-mass galaxies, but within the relation between fmol and the distance to the SFMS. The molecular gas depletion time, Ïdep = Mmol/SFR, is higher than for lower-mass galaxies on the SFMS (Ïdep = 9.30 ± 0.03, compared to Ïdep = 9.00 ± 0.02 for the comparison sample) and seems to continue an increasing trend with stellar mass. HI-FR galaxies have an atomic-to-molecular gas mass ratio that is in agreement with that of lower-mass galaxies, indicating that the conversion from the atomic to molecular gas proceeds in a similar way. We conclude that the availability of molecular gas is a crucial factor to enable star formation to continue and that, if gas is present, quenching is not a necessary destiny for high-mass galaxies. The difference in gas depletion time suggests that the properties of the molecular gas at high stellar masses are less favorable for star formation.Spanish Ministerio de EconomĂa y Competitividad AYA2017-84897-P, PID2020-114414GB-I00European Regional Development Funds (FEDER) AYA2017-84897-P, PID2020-114414GB-I00Junta de AndalucĂa (Spain) FQM108INSU/CNRS (France) 205-19, 068-20MPG (Germany) 205-19, 068-20IGN (Spain) 205-19, 068-20IPACNational Aeronautics and Space Administration
NASACentre National de la Recherche Scientifique
CNR
Radio galaxies and their magnetic fields out to z <= 3
We present polarization properties at 1.4âGHz of two separate extragalactic source populations: passive quiescent galaxies and luminous quasar-like galaxies. We use data from the Wide-Field Infrared Survey Explorer to determine the host galaxy population of the polarized extragalactic radio sources. The quiescent galaxies have higher percentage polarization, smaller radio linear size, and 1.4âGHz luminosity of 6 Ă 1021 < L1.4 < 7 Ă 1025âW Hzâ1, while the quasar-like galaxies have smaller percentage polarization, larger radio linear size at radio wavelengths, and a 1.4âGHz luminosity of 9 Ă 1023 < L1.4 < 7 Ă 1028âW Hzâ1, suggesting that the environment of the quasar-like galaxies is responsible for the lower percentage polarization. Our results confirm previous studies that found an inverse correlation between percentage polarization and total flux density at 1.4âGHz. We suggest that the population change between the polarized extragalactic radio sources is the origin of this inverse correlation and suggest a cosmic evolution of the space density of quiescent galaxies. Finally, we find that the extragalactic contributions to the rotation measures (RMs) of the nearby passive galaxies and the distant quasar-like galaxies are different. After accounting for the RM contributions by cosmological large-scale structure and intervening Mg II absorbers we show that the distribution of intrinsic RMs of the distant quasar-like sources is at most four times as wide as the RM distribution of the nearby quiescent galaxies, if the distribution of intrinsic RMs of the WISEâStar sources itself is at least several rad mâ2 wide
Infrared-faint radio sources: A new population of high-redshift radio galaxies
We present a sample of 1317 Infrared-faint radio sources (IFRSs) that, for the first time, are reliably detected in the infrared, generated by cross-correlating the Wide-field Infrared Survey Explorer (WISE) all-sky survey with major radio surveys. Our IFRSs are brighter in both radio and infrared than the first-generation IFRSs that were undetected in the infrared by the Spitzer Space Telescope. We present the first spectroscopic redshifts of IFRSs, and find that all but one of the IFRSs with spectroscopy have z > 2. We also report the first X-ray counterparts of IFRSs, and present an analysis of radio spectra and polarization, and show that they include gigahertz peaked-spectrum, compact steep-spectrum and ultra-steep-spectrum sources. These results, together with their WISE infrared colours and radio morphologies, imply that our sample of IFRSs represents a population of radio-loud active galactic nuclei at z > 2. We conclude that our sample consists of lower redshift counterparts of the extreme first-generation IFRSs, suggesting that the fainter IFRSs are at even higher redshift
Combined Norepinephrine/Serotonergic Reuptake Inhibition: Effects on Maternal Behavior, Aggression, and Oxytocin in the Rat
Background: Few systematic studies exist on the effects of chronic reuptake of monoamine neurotransmitter systems during pregnancy on the regulation of maternal behavior (MB), although many drugs act primarily through one or more of these systems. Previous studies examining fluoxetine and amfonelic acid treatment during gestation on subsequent MB in rodents indicated significant alterations in postpartum maternal care, aggression, and oxytocin levels. In this study, we extended our studies to include chronic gestational treatment with desipramine or amitriptyline to examine differential effects of reuptake inhibition of norepinephrine and combined noradrenergic and serotonergic systems on MB, aggression, and oxytocin system changes. Methods: Pregnant Sprague-Dawley rats were treated throughout gestation with saline or one of three doses of either desipramine, which has a high affinity for the norepinephrine monoamine transporter, or amitriptyline, an agent with high affinity for both the norepinephrine and serotonin monoamine transporters. MB and postpartum aggression were assessed on postpartum days 1 and 6 respectively. Oxytocin levels were measured in relevant brain regions on postpartum day 7. Predictions were that amitriptyline would decrease MB and increase aggression relative to desipramine, particularly at higher doses. Amygdaloidal oxytocin was expected to decrease with increased aggression. Results: Amitriptyline and desipramine differentially reduced MB, and at higher doses reduced aggressive behavior. Hippocampal oxytocin levels were lower after treatment with either drug but were not correlated with specific behavioral effects. These results, in combination with previous findings following gestational treatment with other selective neurotransmitter reuptake inhibitors, highlight the diverse effects of multiple monoamine systems thought to be involved in maternal care
The 6df galaxy survey: The near-infrared fundamental plane of early-type galaxies
We determine the near-infrared Fundamental Plane (FP) for ~10 4 early-type galaxies in the 6-degree Field Galaxy Survey (6dFGS). We fit the distribution of central velocity dispersion, near-infrared surface brightness and half-light radius with a 3D Gaussian model using a maximum-likelihood method. The model provides an excellent empirical fit to the observed FP distribution and the method proves robust and unbiased. Tests using simulations show that it gives superior results to regression techniques in the presence of significant and correlated uncertainties in all three parameters, censoring of the data by various selection effects and outliers in the data sample. For the 6dFGS J-band sample we find an FP with ReâÏ01.52±0.03Ie-0.89±0.01, similar to previous near-infrared determinations and consistent with the H- and K-band FPs once allowance is made for differences in mean colour. The overall scatter in R e about the FP is Ï r = 29 per cent, and is the quadrature sum of an 18 per cent scatter due to observational errors and a 23 per cent intrinsic scatter. Because of the Gaussian distribution of galaxies in FP space, Ï r is not the distance error, which we find to be Ï d = 23 per cent. Using group richness and local density as measures of environment, and morphologies based on visual classifications, we find that the FP slopes do not vary with environment or morphology. However, for fixed velocity dispersion and surface brightness, field galaxies are on average 5 per cent larger than galaxies in groups or higher density environments, and the bulges of early-type spirals are on average 10 per cent larger than ellipticals and lenticulars. The residuals about the FP show significant trends with environment, morphology and stellar population. The strongest trend is with age, and we speculate that age is the most important systematic source of offsets from the FP, and may drive the other trends through its correlations with environment, morphology and metallicity. These results will inform our use of the near-infrared FP in deriving relative distances and peculiar velocities for 6dFGS galaxies
Ultraviolet through far-infrared spatially resolved analysis of the recent star formation in M81 (NGC 3031)
The recent star formation (SF) in the early-type spiral galaxy M81 is characterized using imaging observations from the far-ultraviolet to the far-infrared. We compare these data with models of the stellar, gas, and dust emission for subgalactic regions. Our results suggest the existence of a diffuse dust emission not directly linked to the recent star formation. We find a radial decrease of the dust temperature and dust mass density, and in the attenuation of the stellar light. The IR emission in M81 can be modeled with three components: (1) cold dust with a temperature = 18 ± 2 K, concentrated near the H II regions but also presenting a diffuse distribution; (2) warm dust with = 53 ± 7 K, directly linked with the H II regions; and (3) aromatic molecules, with diffuse morphology peaking around the H II regions. We derive several relationships to obtain total IR luminosities from IR monochromatic fluxes, and we compare five different star formation rate (SFR) estimators for H II regions in M81 and M51: the UV, H alpha, and three estimators based on Spitzer data. We find that the H alpha luminosity absorbed by dust correlates tightly with the 24 mu m emission. The correlation with the total IR luminosity is not as good. Important variations from galaxy to galaxy are found when estimating the total SFR with the 24 mu m or the total IR emission alone. The most reliable estimations of the total SFRs are obtained by combining the H alpha emission (or the UV) and an IR luminosity (especially the 24 mu m emission), which probe the unobscured and obscured SF, respectively. For the entire M81 galaxy, about 50% of the total SF is obscured by dust. The percentage of obscured SF ranges from 60% in the inner regions of the galaxy to 30% in the outer zones
The 2MASS Redshift Survey in the Zone of Avoidance
The Two Micron All-Sky Survey (2MASS) Redshift Survey was started two decades ago with the goal of mapping the three-dimensional distribution of an all-sky flux-limited (K s < 11.75 mag) sample of ~45,000 galaxies. Our first data release presented an unprecedented uniform coverage for most of the celestial sphere, with redshifts for ~98% of our sample. However, we were missing redshifts for ~18% of the catalog entries that were located within the "Zone of Avoidance" ()âan important region of the sky for studies of the large-scale structure and cosmic flows. In this second and final data release, we present redshifts for all 1041 2MRS galaxies that previously lacked this information, as well as updated measurements for 27 others.Fil: Macri, Lucas M.. Texas A&M University; Estados UnidosFil: Kraan Korteweg, Renee Christine. University of Cape Town; SudĂĄfricaFil: Lambert, Trystan. South African Astronomical Observatory; SudĂĄfricaFil: Alonso, Maria Victoria. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba. Instituto de AstronomĂa TeĂłrica y Experimental. Universidad Nacional de CĂłrdoba. Observatorio AstronĂłmico de CĂłrdoba. Instituto de AstronomĂa TeĂłrica y Experimental; ArgentinaFil: Berlind, Perry. South African Astronomical Observatory; SudĂĄfricaFil: Calkins, Michael. Harvard-Smithsonian Center for Astrophysics; Estados UnidosFil: Erdogdu, Pirin. University College London. Department of Physics and Astronomy; Reino UnidoFil: Falco, Emilio. Harvard-Smithsonian Center for Astrophysics; Estados UnidosFil: Jarrett, Thomas. University of Cape Town; SudĂĄfricaFil: Mink, Jessica. Harvard-Smithsonian Center for Astrophysics; Estados Unido
A Break in Spiral Galaxy Scaling Relations at the Upper Limit of Galaxy Mass
Super spirals are the most massive star-forming disk galaxies in the universe. We measured rotation curves for 23 massive spirals with the Southern African Large Telescope (SALT) and found a wide range of fast rotation speeds (240â570 km s^(â1)), indicating enclosed dynamical masses of (0.6â4) Ă 10^(12) Mâ. Super spirals with mass in stars log M_(stars)/Mâ > 11.5 break from the baryonic TullyâFisher relation (BTFR) established for lower-mass galaxies. The BTFR power-law index breaks from 3.75 ± 0.11 to 0.25 ± 0.41 above a rotation speed of ~340 km s^(â1). Super spirals also have very high specific angular momenta that break from the Fall relation. These results indicate that super spirals are undermassive for their dark matter halos, limited to a mass in stars of log M_(stars)/Mâ < 11.8. Most giant elliptical galaxies also obey this fundamental limit, which corresponds to a critical dark halo mass of log M_(halo)/Mâ â 12.7. Once a halo reaches this mass, its gas can no longer cool and collapse in a dynamical time. Super spirals survive today in halos as massive as log M_(halo)/Mâ â 13.6, continuing to form stars from the cold baryons they captured before their halos reached critical mass. The observed high-mass break in the BTFR is inconsistent with the Modified Newtonian Dynamics theory
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