scholarly journals Metallicity gradients of galaxies in the Herschel Reference Survey

2014 ◽  
Vol 10 (S309) ◽  
pp. 320-320
Author(s):  
Thomas M. Hughes
Keyword(s):  
Far Infrared ◽  
Pilot Project ◽  
Strong Emission ◽  
Star Forming ◽  
Star Forming Regions ◽  
Very Large Telescope ◽  
Photometric Observations ◽  
The Galaxy ◽  
Nearby Galaxies ◽  
Cold Dust

AbstractWe introduce a pilot project to measure metallicitiy gradients for a sample of twenty nearby galaxies drawn from the Herschel Reference Survey (HRS), representative of normal, star-forming spiral galaxies. We have obtained optical spectroscopic observations using the Very Large Telescope with the FORS2 instrument in multi-object mode, targeting individual Hii and star-forming regions across the galaxy discs (P. I.: L. Cortese). From the ratios of the strong emission lines, we estimate the local gas-phase oxygen abundance and construct metallicity gradients. Combining these new data with Herschel PACS/SPIRE far-infrared photometric observations and Hi 21 cm line maps, to trace the cold dust and gas respectively, will allow the study of the relationships between stars, gas, dust and metals on sub-kiloparsec scales.

scholarly journals Ionized and neutral gas in the XUV discs of nearby spiral galaxies

2014 ◽  
Vol 10 (S309) ◽  
pp. 65-68
Author(s):  
López-Sánchez ◽  
B. S. Koribalski ◽  
T. Westmeier ◽  
C. Esteban
Keyword(s):  
Spiral Galaxies ◽  
Dwarf Galaxy ◽  
Chemical Abundances ◽  
Ionized Gas ◽  
Galaxy Interactions ◽  
Star Forming ◽  
Star Forming Regions ◽  
Neutral Gas ◽  
The Galaxy ◽  
Nearby Galaxies

AbstractWe are conducting a multiwavelength study of XUV discs in nearby, gas-rich spiral galaxies combining the available UV (GALEX) observations with H i data obtained at the ATCA as part of the Local Volume HI Survey (LVHIS) project and multi-object fibre spectroscopy obtained using the 2dF/AAOmega instrument at the 3.9m AAT. Here we present the results of the multiwavelength analysis of the galaxy pair NGC 1512/1510. The H i distribution of NGC 1512 is very extended with two pronounced spiral/tidal arms. Hundreds of independent UV-bright regions are associated with dense H i clouds in the galaxy outskirts. We confirm the detection of ionized gas in the majority of them and characterize their physical properties, chemical abundances and kinematics. Both the gas distribution andthe distribution of the star-forming regions are affected by gravitational interactionwith the neighbouring blue compact dwarf galaxy NGC 1510. Our multiwavelength analysis provides new clues about local star-formation processes, the metal redistribution in the outer gaseous discs of spiral galaxies, the importance of galaxy interactions, the fate of the neutral gas and the chemical evolution in nearby galaxies.

scholarly journals The Distribution of Young Stars in Nearby Galaxies

1986 ◽  
Vol 116 ◽  
pp. 61-80 ◽  
Author(s):  
W. L. Freedman
Keyword(s):  
Spatial Distribution ◽  
Milky Way ◽  
Young Stars ◽  
Panoramic View ◽  
Star Forming ◽  
Individual Stars ◽  
Star Forming Regions ◽  
The Galaxy ◽  
External Galaxies ◽  
Nearby Galaxies

Although luminous stars are relatively rare, they can potentially be studied out to large distances. In our own Milky Way, this advantage is offset by obscuration due to dust in the plane of the Galaxy. In addition, distances to these individual stars are extremely difficult to determine. The study of external galaxies allows a panoramic view of the system and its individually brightest stars which are all at a common distance. The spatial distribution of star forming regions is immediately apparent, and the effects of obscuration are minimized. Nearby resolved galaxies therefore provide a rich resource for examining the properties of the intrinsically brightest stars and their relation to other components of the galaxy.

scholarly journals Early galaxy growth: mergers or gravitational instability?

2020 ◽  
Vol 500 (1) ◽  
pp. 118-137
Author(s):  
A Zanella ◽  
A Pallottini ◽  
A Ferrara ◽  
S Gallerani ◽  
S Carniani ◽  
...  
Keyword(s):  
Gravitational Instability ◽  
Far Infrared ◽  
Joint Effect ◽  
Data Sets ◽  
Star Forming ◽  
Spatially Resolved ◽  
Star Forming Regions ◽  
James Webb Space Telescope ◽  
The Galaxy ◽  
Hydrodynamical Simulations

ABSTRACT We investigate the spatially resolved morphology of galaxies in the early Universe. We consider a typical redshift z = 6 Lyman break galaxy, ‘Althæa’, from the SERRA hydrodynamical simulations. We create mock rest-frame ultraviolet (UV), optical, and far-infrared observations, and perform a two-dimensional morphological analysis to deblend the galaxy disc from substructures (merging satellites or star-forming regions). We find that the [C ii]158 μm emitting region has an effective radius 1.5–2.5 times larger than the optical one, consistent with recent observations. This [C ii] halo in our simulated galaxy arises as the joint effect of stellar outflows and carbon photoionization by the galaxy UV field, rather than from the emission of unresolved nearby satellites. At the typical angular resolution of current observations (≳ 0.15 arcsec) only merging satellites can be detected; detection of star-forming regions requires resolutions of ≲ 0.05 arcsec. The [C ii]-detected satellite has a 2.5-kpc projected distance from the galaxy disc, whereas the star-forming regions are embedded in the disc itself (distance ≲ 1 kpc). This suggests that multicomponent systems reported in the literature, which have separations ≳ 2 kpc, are merging satellites, rather than galactic substructures. Finally, the star-forming regions found in our mock maps follow the local L[C ii]–SFRUV relation of galaxy discs, although sampling the low-luminosity, low-SFR tail of the distribution. We show that future James Webb Space Telescope observations, bridging UV and [C ii] data sets, will be exceptionally suited to characterize galaxy substructures, thanks to their exquisite spatial resolution and sensitivity to both low-metallicity and dust-obscured regions that are bright at infrared wavelengths.

scholarly journals The case for thermalization as a contributor to the [C ii] deficit

2021 ◽  
Vol 503 (1) ◽  
pp. 911-919
Author(s):  
Jessica Sutter ◽  
Daniel A Dale ◽  
Karin Sandstrom ◽  
J D T Smith ◽  
Alberto Bolatto ◽  
...  
Keyword(s):  
Far Infrared ◽  
Infrared Emission ◽  
Continuum Emission ◽  
H Ii Regions ◽  
Observable Universe ◽  
Star Forming ◽  
Star Forming Regions ◽  
Wide Range ◽  
Nearby Galaxies ◽  
Selection Of

ABSTRACT The [C ii] deficit, which describes the observed decrease in the ratio of [C ii] 158 μm emission to continuum infrared emission in galaxies with high star formation surface densities, places a significant challenge to the interpretation of [C ii] detections from across the observable universe. In an attempt to further decode the cause of the [C ii] deficit, the [C ii] and dust continuum emission from 18 Local Volume galaxies has been split based on conditions within the interstellar medium where it originated. This is completed using the Key Insights in Nearby Galaxies: a Far-Infrared Survey with Herschel (KINGFISH) and Beyond the Peak (BtP) surveys and the wide-range of wavelength information, from UV to far-infrared emission lines, available for a selection of star-forming regions within these samples. By comparing these subdivided [C ii] emissions to isolated infrared emission and other properties, we find that the thermalization (collisional de-excitation) of the [C ii] line in H ii regions plays a significant role in the deficit observed in our sample.

scholarly journals PÉGASE.3: A code for modeling the UV-to-IR/submm spectral and chemical evolution of galaxies with dust

2019 ◽  
Vol 623 ◽  
pp. A143 ◽  
Author(s):  
Michel Fioc ◽  
Brigitte Rocca-Volmerange
Keyword(s):  
Near Infrared ◽  
Far Infrared ◽  
Spectral Energy ◽  
Star Forming ◽  
Star Forming Regions ◽  
The Galaxy ◽  
History Of ◽  
Mass Assembly ◽  
Individual Grains ◽  
The Masses

A code computing consistently the evolution of stars, gas and dust, as well as the energy they radiate, is required to derive reliably the history of galaxies by fitting synthetic spectral energy distributions (SEDs) to multiwavelength observations. The new code PÉGASE.3 described in this paper extends to the far-infrared/submillimeter the ultraviolet-to-near-infrared modeling provided by previous versions of PÉGASE. It first computes the properties of single stellar populations at various metallicities. It then follows the evolution of the stellar light of a galaxy and the abundances of the main metals in the interstellar medium (ISM), assuming some scenario of mass assembly and star formation. It simultaneously calculates the masses of the various grain families, the optical depth of the galaxy and the attenuation of the SED through the diffuse ISM in spiral and spheroidal galaxies, using grids of radiative transfer precomputed with Monte Carlo simulations taking scattering into account. The code determines the mean radiation field and the temperature probability distribution of stochastically heated individual grains. It then sums up their spectra to yield the overall emission by dust in the diffuse ISM. The nebular emission of the galaxy is also computed, and a simple modeling of the effects of dust on the SED of star-forming regions is implemented. The main outputs are ultraviolet-to-submillimeter SEDs of galaxies from their birth up to 20 Gyr, colors, masses of galactic components, ISM abundances of metallic elements and dust species, supernova rates. The temperatures and spectra of individual grains are also available. The paper discusses several of these outputs for a scenario representative of Milky Way-like spirals. PÉGASE.3 is fully documented and its Fortran 95 source files are public. The code should be especially useful for cosmological simulations and to interpret future mid- and far-infrared data, whether obtained by JWST, LSST, Euclid or e-ELT.

scholarly journals Reproducing the Universe: a comparison between the EAGLE simulations and the nearby DustPedia galaxy sample

2020 ◽  
Vol 494 (2) ◽  
pp. 2823-2838 ◽  
Author(s):  
Ana Trčka ◽  
Maarten Baes ◽  
Peter Camps ◽  
Sharon E Meidt ◽  
James Trayford ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Physical Properties ◽  
Numerical Models ◽  
Far Infrared ◽  
Spectral Energy ◽  
Star Forming ◽  
Star Forming Regions ◽  
Global Emission ◽  
Galaxy Sample ◽  
Galaxy Population

ABSTRACT We compare the spectral energy distributions (SEDs) and inferred physical properties for simulated and observed galaxies at low redshift. We exploit UV-submillimetre mock fluxes of ∼7000 z = 0 galaxies from the EAGLE suite of cosmological simulations, derived using the radiative transfer code skirt. We compare these to ∼800 observed galaxies in the UV-submillimetre range, from the DustPedia sample of nearby galaxies. To derive global properties, we apply the SED fitting code cigale consistently to both data sets, using the same set of ∼80 million models. The results of this comparison reveal overall agreement between the simulations and observations, both in the SEDs and in the derived physical properties, with a number of discrepancies. The optical and far-infrared regimes, and the scaling relations based upon the global emission, diffuse dust, and stellar mass, show high levels of agreement. However, the mid-infrared fluxes of the EAGLE galaxies are overestimated while the far-UV domain is not attenuated enough, compared to the observations. We attribute these discrepancies to a combination of galaxy population differences between the samples and limitations in the subgrid treatment of star-forming regions in the EAGLE-skirt post-processing recipe. Our findings show the importance of detailed radiative transfer calculations and consistent comparison, and provide suggestions for improved numerical models.

Mid- to far-infrared mapping spectroscopy of galactic star-forming regions with ISO, spitzer, and AKARI

2008 ◽  
Vol 31 ◽  
pp. 191-192
Author(s):  
Y. Okada ◽  
T. Onaka ◽  
T. Miyata ◽  
Y.K. Okamoto ◽  
I. Sakon ◽  
...  
Keyword(s):  
Far Infrared ◽  
Star Forming ◽  
Star Forming Regions

scholarly journals Less than the sum of its parts: the dust-corrected H α luminosity of star-forming galaxies explored at different spatial resolutions with MaNGA and MUSE

2020 ◽  
Vol 498 (3) ◽  
pp. 4205-4221
Author(s):  
N Vale Asari ◽  
V Wild ◽  
A L de Amorim ◽  
A Werle ◽  
Y Zheng ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Formation Rate ◽  
Flux Ratio ◽  
Star Forming ◽  
The Galaxy ◽  
Nearby Galaxies ◽  
Point To Point ◽  
Dust Attenuation ◽  
The Impact ◽  
Lower Limits

ABSTRACT The H α and H β emission-line luminosities measured in a single integrated spectrum are affected in non-trivial ways by point-to-point variations in dust attenuation in a galaxy. This work investigates the impact of this variation when estimating global H α luminosities corrected for the presence of dust by a global Balmer decrement. Analytical arguments show that the dust-corrected H α luminosity is always underestimated when using the global H α/H β flux ratio to correct for dust attenuation. We measure this effect on 156 face-on star-forming galaxies from the Mapping Nearby Galaxies at APO (MaNGA) survey. At 1–2 kpc spatial resolution, the effect is small but systematic, with the integrated dust-corrected H α luminosity underestimated by 2–4 per cent (and typically not more than by 10 per cent), and depends on the specific star formation rate of the galaxy. Given the spatial resolution of MaNGA, these are lower limits for the effect. From Multi Unit Spectroscopic Explorer (MUSE) observations of NGC 628 with a resolution of 36 pc, we find the discrepancy between the globally and the point-by-point dust-corrected H α luminosity to be 14 ± 1 per cent, which may still underestimate the true effect. We use toy models and simulations to show that the true difference depends strongly on the spatial variance of the H α/H β flux ratio, and on the slope of the relation between H αluminosity and dust attenuation within a galaxy. Larger samples of higher spatial resolution observations are required to quantify the dependence of this effect as a function of galaxy properties.

scholarly journals Dust in the Magellanic Clouds

1991 ◽  
Vol 148 ◽  
pp. 57-62
Author(s):  
Paul Hodge
Keyword(s):  
Heavy Element ◽  
Magellanic Clouds ◽  
Dust Content ◽  
Optical Observations ◽  
Optical Data ◽  
Star Forming ◽  
Element Abundances ◽  
Star Forming Regions ◽  
The Galaxy ◽  
Far Ultraviolet

The dust content of the Magellanic Clouds can be studied using optical, ultraviolet, infrared and, indirectly, radio wavelength data. All recent studies show that the dust content is lower than that of the Milky Way Galaxy for both Clouds and that the optical properties of the dust are different. At ultraviolet wavelengths, the 2165 Å “bump” in the extinction curve is significantly smaller than in the Galaxy (this now appears NOT to be a consequence of the lower heavy element abundances) and the far ultraviolet (shortward of ˜2000 Å) extinction is greater than in the Galaxy (this IS likely to be a consequence of the lower heavy element abundances). New optical data on background galaxies suggest that the total extinction in the central parts of both the LMC and the SMC is approximately 1.5 magnitudes. High local extinction values are derived from uv and optical observations of star-forming regions, where a spatial correlation with CO detections is sometimes, but not always, found.

scholarly journals High-J CO Intensity Measurements for Galaxies Observed by the Herschel FTS

2015 ◽  
Vol 11 (S315) ◽  
pp. 26-29
Author(s):  
Julia Kamenetzky ◽  
Naseem Rangwala ◽  
Jason Glenn ◽  
Philip Maloney ◽  
Alex Conley
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Raw Material ◽  
Molecular Gas ◽  
Star Forming ◽  
Star Forming Regions ◽  
J 13 ◽  
Systematic Effects ◽  
Nearby Galaxies ◽  
Co Emission

AbstractMolecular gas is the raw material for star formation and is commonly traced by the carbon monoxide (CO) molecule. The atmosphere blocks all but the lowest-J transitions of CO for observatories on the ground, but the launch of the Herschel Space Observatory revealed the CO emission of nearby galaxies from J = 4−3 to J = 13−12. Herschel showed that mid- and high-J CO lines in nearby galaxies are emitted from warm gas, accounting for approximately 10% of the molecular mass, but the majority of the CO luminosity. The energy budget of this warm, highly-excited gas is a significant window into the feedback interactions among molecular gas, star formation, and galaxy evolution. Likely, mechanical heating is required to explain the excitation. Such gas has also been observed in star forming regions within our galaxy.We have examined all ~300 spectra of galaxies from the Herschel Fourier Transform Spectrometer and measured line fluxes or upper limits for the CO J = 4−3 to J = 13−12, [CI], and [NII] 205 micron lines in ~200 galaxies, taking systematic effects of the FTS into account. We will present our line fitting method, illustrate trends available so far in this large sample, and preview the full 2-component radiative transfer likelihood modeling of the CO emission using an illustrative sample of 20 galaxies, including comparisons to well-resolved galactic regions. This work is a comprehensive study of mid- and high-J CO emission among a variety of galaxy types, and can be used as a resource for future (sub)millimeter studies of galaxies with ground-based instruments.

Sign in / Sign up

Export Citation Format

Share Document