scholarly journals J-PLUS: Measuring Hα emission line fluxes in the nearby universe

2019 ◽  
Vol 622 ◽  
pp. A180 ◽  
Author(s):  
R. Logroño-García ◽  
G. Vilella-Rojo ◽  
C. López-Sanjuan ◽  
J. Varela ◽  
K. Viironen ◽  
...  
Keyword(s):  
Star Formation ◽  
Emission Line ◽  
Star Formation Rate ◽  
Narrow Band ◽  
Formation Rate ◽  
Photometric Data ◽  
Star Forming ◽  
Spatially Resolved ◽  
Band Filter ◽  
Narrow Band Filter

In this paper we aim to validate a methodology designed to obtain Hα emission line fluxes from J-PLUS photometric data. J-PLUS is a multi narrow-band filter survey carried out with the 2 deg2 field of view T80Cam camera, mounted on the JAST/T80 telescope in the OAJ, Teruel, Spain. The information of the twelve J-PLUS bands, including the J0660 narrow-band filter located at rest-frame Hα, is used over the first 42 deg2 observed to retrieve de-reddened and [NII] decontaminated Hα emission line fluxes of 46 star-forming regions with previous SDSS and/or CALIFA spectroscopic information. The agreement between the J-PLUS Hα fluxes and those obtained with spectroscopic data is remarkable, finding a median comparison ratio with a scatter of $ \mathcal{R}\,{=}\,F^{\mathrm{J-PLUS}}_{\mathrm{H\alpha}}/F^{\mathrm{spec}}_{\mathrm{H\alpha}}\,{=}\,1.05\,{\pm}\,0.25 $. This demonstrates that it is possible to retrieve reliable Hα emission line fluxes from J-PLUS photometric data. With an expected area of thousands of square degrees upon completion, the J-PLUS dataset will allow the study of several star formation science cases in the nearby universe, as the spatially resolved star formation rate of nearby galaxies at z  ≤  0.015, and how it is influenced by the environment, morphology, stellar mass, and nuclear activity. As an illustrative example, the close pair of interacting galaxies NGC 3994 and NGC 3995 is analysed, finding an enhancement of the star formation rate not only in the centre, but also in outer parts of the disk of NGC 3994.

scholarly journals A cautionary tale of attenuation in star-forming regions

2020 ◽  
Vol 494 (4) ◽  
pp. 4751-4770 ◽  
Author(s):  
Mallory Molina ◽  
Nikhil Ajgaonkar ◽  
Renbin Yan ◽  
Robin Ciardullo ◽  
Caryl Gronwall ◽  
...  
Keyword(s):  
Star Formation ◽  
Emission Line ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Dust Content ◽  
Physical Parameters ◽  
Star Forming ◽  
Total Dust ◽  
Star Forming Regions ◽  
Field Unit

ABSTRACT The attenuation of light from star-forming galaxies is correlated with a multitude of physical parameters including star formation rate, metallicity and total dust content. This variation in attenuation is even more evident on kiloparsec scales, which is the relevant size for many current spectroscopic integral field unit surveys. To understand the cause of this variation, we present and analyse Swift/UVOT near-UV (NUV) images and SDSS/MaNGA emission-line maps of 29 nearby (z < 0.084) star-forming galaxies. We resolve kiloparsec-sized star-forming regions within the galaxies and compare their optical nebular attenuation (i.e. the Balmer emission line optical depth, $\tau ^{l}_{B}\equiv \tau _{\textrm {H}\beta }-\tau _{\textrm {H}\alpha }$) and NUV stellar continuum attenuation (via the NUV power-law index, β) to the attenuation law described by Battisti et al. We show the data agree with that model, albeit with significant scatter. We explore the dependence of the scatter of the β–$\tau ^{l}_{B}$ measurements from the star-forming regions on different physical parameters, including distance from the nucleus, star formation rate and total dust content. Finally, we compare the measured $\tau ^{l}_{B}$ and β values for the individual star-forming regions with those of the integrated galaxy light. We find a strong variation in β between the kiloparsec scale and the larger galaxy scale that is not seen in $\tau ^{l}_{B}$. We conclude that the sightline dependence of UV attenuation and the reddening of β due to the light from older stellar populations could contribute to the scatter in the β–$\tau ^{l}_{B}$ relation.

scholarly journals A contribution of star-forming clumps and accreting satellites to the mass assembly of z ∼ 2 galaxies

2019 ◽  
Vol 489 (2) ◽  
pp. 2792-2818 ◽  
Author(s):  
A Zanella ◽  
E Le Floc’h ◽  
C M Harrison ◽  
E Daddi ◽  
E Bernhard ◽  
...  
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Stellar Mass ◽  
Mass Ratio ◽  
Star Forming ◽  
Spatially Resolved ◽  
The Galaxy ◽  
Mass Assembly

ABSTRACT We investigate the contribution of clumps and satellites to the galaxy mass assembly. We analysed spatially resolved HubbleSpace Telescope observations (imaging and slitless spectroscopy) of 53 star-forming galaxies at z ∼ 1–3. We created continuum and emission line maps and pinpointed residual ‘blobs’ detected after subtracting the galaxy disc. Those were separated into compact (unresolved) and extended (resolved) components. Extended components have sizes ∼2 kpc and comparable stellar mass and age as the galaxy discs, whereas the compact components are 1.5 dex less massive and 0.4 dex younger than the discs. Furthermore, the extended blobs are typically found at larger distances from the galaxy barycentre than the compact ones. Prompted by these observations and by the comparison with simulations, we suggest that compact blobs are in situ formed clumps, whereas the extended ones are accreting satellites. Clumps and satellites enclose, respectively, ∼20 per cent and ≲80 per cent of the galaxy stellar mass, ∼30 per cent and ∼20 per cent of its star formation rate. Considering the compact blobs, we statistically estimated that massive clumps (M⋆ ≳ 109 M⊙) have lifetimes of ∼650 Myr, and the less massive ones (108 < M⋆ < 109 M⊙) of ∼145 Myr. This supports simulations predicting long-lived clumps (lifetime ≳ 100 Myr). Finally, ≲30 per cent (13 per cent) of our sample galaxies are undergoing single (multiple) merger(s), they have a projected separation ≲10 kpc, and the typical mass ratio of our satellites is 1:5 (but ranges between 1:10 and 1:1), in agreement with literature results for close pair galaxies.

scholarly journals Are galactic star formation and quenching governed by local, global, or environmental phenomena?

2019 ◽  
Vol 492 (1) ◽  
pp. 96-139 ◽  
Author(s):  
Asa F L Bluck ◽  
Roberto Maiolino ◽  
Sebastian F Sánchez ◽  
Sara L Ellison ◽  
Mallory D Thorp ◽  
...  
Keyword(s):  
Star Formation ◽  
Velocity Dispersion ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Empirical Relationship ◽  
Environmental Parameters ◽  
Single Parameter ◽  
Star Forming ◽  
Spatially Resolved ◽  
Artificial Neural Network Ann

ABSTRACT We present an analysis of star formation and quenching in the SDSS-IV MaNGA-DR15, utilizing over 5 million spaxels from ∼3500 local galaxies. We estimate star formation rate surface densities (ΣSFR) via dust corrected H α flux where possible, and via an empirical relationship between specific star formation rate (sSFR) and the strength of the 4000 Å break (D4000) in all other cases. We train a multilayered artificial neural network (ANN) and a random forest (RF) to classify spaxels into ‘star-forming’ and ‘quenched’ categories given various individual (and groups of) parameters. We find that global parameters (pertaining to the galaxy as a whole) perform collectively the best at predicting when spaxels will be quenched, and are substantially superior to local/spatially resolved and environmental parameters. Central velocity dispersion is the best single parameter for predicting quenching in central galaxies. We interpret this observational fact as a probable consequence of the total integrated energy from active galactic neucleus (AGN) feedback being traced by the mass of the black hole, which is well known to correlate strongly with central velocity dispersion. Additionally, we train both an ANN and RF to estimate ΣSFR values directly via regression in star-forming regions. Local/spatially resolved parameters are collectively the most predictive at estimating ΣSFR in these analyses, with stellar mass surface density at the spaxel location (Σ*) being by far the best single parameter. Thus, quenching is fundamentally a global process but star formation is governed locally by processes within each spaxel.

scholarly journals The evolution of the equivalent width of the Hα emission line and specific star formation rate in star-forming galaxies at 1 < z < 5

2016 ◽  
Vol 460 (4) ◽  
pp. 3587-3597 ◽  
Author(s):  
E. Mármol-Queraltó ◽  
R. J. McLure ◽  
F. Cullen ◽  
J. S. Dunlop ◽  
A. Fontana ◽  
...  
Keyword(s):  
Star Formation ◽  
Emission Line ◽  
Equivalent Width ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Star Forming ◽  
Hα Emission

scholarly journals What drives galaxy quenching? Resolving molecular gas and star formation in the green valley

2020 ◽  
Vol 498 (1) ◽  
pp. L66-L71 ◽  
Author(s):  
Simcha Brownson ◽  
Francesco Belfiore ◽  
Roberto Maiolino ◽  
Lihwai Lin ◽  
Stefano Carniani
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Gas Content ◽  
Molecular Gas ◽  
Data Sets ◽  
Star Forming ◽  
Spatially Resolved ◽  
Star Forming Regions ◽  
Central Regions

ABSTRACT We study quenching in seven green valley galaxies on kpc scales by resolving their molecular gas content using 12CO(1–0) observations obtained with NOrthern Extended Millimeter Array and Atacama Large Millimeter Array, and their star formation rate using spatially resolved optical spectroscopy from the Mapping Nearby Galaxies at Apache Point Observatory survey. We perform radial stacking of both data sets to increase the sensitivity to molecular gas and star formation, thereby avoiding biases against strongly quenched regions. We find that both spatially resolved gas fraction (fgas) and star formation efficiency ($\rm {SFE}$) are responsible for quenching green valley galaxies at all radii: both quantities are suppressed with respect to typical star-forming regions. fgas and $\rm {SFE}$ have roughly equal influence in quenching the outer disc. We are, however, unable to identify the dominant mechanism in the strongly quenched central regions. We find that fgas is reduced by $\rm \sim\! 1~dex$ in the central regions, but the star formation rate is too low to be measured, leading to upper limits for the $\rm {SFE}$. Moving from the outer disc to central regions, the reduction in fgas is driven by an increasing $\rm \Sigma _{\star }$ profile rather than a decreasing $\rm \Sigma _{H_{2}}$ profile. The reduced fgas may therefore be caused by a decrease in the gas supply rather than molecular gas ejection mechanisms, such as winds driven by active galactic nuclei. We warn more generally that studies investigating fgas may be deceiving in inferring the cause of quenching, particularly in the central (bulge-dominated) regions of galaxies.

scholarly journals Properties of galaxies with an offset between the position angles of the major kinematic and photometric axes

2020 ◽  
Vol 634 ◽  
pp. A26 ◽  
Author(s):  
L. S. Pilyugin ◽  
E. K. Grebel ◽  
I. A. Zinchenko ◽  
J. M. Vílchez ◽  
F. Sakhibov ◽  
...  
Keyword(s):  
Star Formation ◽  
Surface Brightness ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Velocity Fields ◽  
Oxygen Abundance ◽  
Star Forming ◽  
Measured Position ◽  
Central Oxygen ◽  
Straight Lines

We derive the photometric, kinematic, and abundance characteristics of 18 star-forming MaNGA galaxies with fairly regular velocity fields and surface brightness distributions and with a large offset between the measured position angles of the major kinematic and photometric axes, ΔPA ≳ 20°. The aim is to examine if there is any other distinctive characteristic common to these galaxies. We found morphological signs of interaction in some (in 11 out of 18) but not in all galaxies. The observed velocity fields show a large variety; the maps of the isovelocities vary from an hourglass-like appearance to a set of straight lines. The position angles of the major kinematic axes of the stellar and gas rotations are close to each other. The values of the central oxygen abundance, radial abundance gradient, and star formation rate are distributed within the intervals defined by galaxies with small (no) ΔPA of similar mass. Thus, we do not find any specific characteristic common to all galaxies with large ΔPA. Instead, the properties of these galaxies are similar to those of galaxies with small (no) ΔPA. This suggests that either the reason responsible for the large ΔPA does not influence other characteristics or the galaxies with large ΔPA do not share a common origin, they can, instead, originate through different channels.

scholarly journals Morphometry as a probe of the evolution of jellyfish galaxies: evidence of broadening in the surface brightness profiles of ram-pressure stripping candidates in the multicluster system A901/A902

2020 ◽  
Vol 500 (1) ◽  
pp. 40-53
Author(s):  
Fernanda Roman-Oliveira ◽  
Ana L Chies-Santos ◽  
Fabricio Ferrari ◽  
Geferson Lucatelli ◽  
Bruno Rodríguez Del Pino
Keyword(s):  
Star Formation ◽  
Surface Brightness ◽  
Quantitative Measurement ◽  
Star Formation Rate ◽  
Hubble Space Telescope ◽  
Formation Rate ◽  
Structural Evolution ◽  
Star Forming ◽  
Irregular Structures ◽  
Ram Pressure

ABSTRACT We explore the morphometric properties of a group of 73 ram-pressure stripping candidates in the A901/A902 multicluster system, at z∼ 0.165, to characterize the morphologies and structural evolution of jellyfish galaxies. By employing a quantitative measurement of morphometric indicators with the algorithm morfometryka on Hubble Space Telescope (F606W) images of the galaxies, we present a novel morphology-based method for determining trail vectors. We study the surface brightness profiles and curvature of the candidates and compare the results obtained with two analysis packages, morfometryka and iraf/ellipse on retrieving information of the irregular structures present in the galaxies. Our morphometric analysis shows that the ram-pressure stripping candidates have peculiar concave regions in their surface brightness profiles. Therefore, these profiles are less concentrated (lower Sérsic indices) than other star-forming galaxies that do not show morphological features of ram-pressure stripping. In combination with morphometric trail vectors, this feature could both help identify galaxies undergoing ram-pressure stripping and reveal spatial variations in the star formation rate.

scholarly journals The ionization parameter of star-forming galaxies evolves with the specific star formation rate

2018 ◽  
Vol 477 (4) ◽  
pp. 5568-5589 ◽  
Author(s):  
Melanie Kaasinen ◽  
Lisa Kewley ◽  
Fuyan Bian ◽  
Brent Groves ◽  
Daichi Kashino ◽  
...  
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Star Forming ◽  
Ionization Parameter

scholarly journals THE STAR-FORMATION-RATE-DENSITY RELATION AT 0.6

2011 ◽  
Vol 735 (1) ◽  
pp. 53 ◽  
Author(s):  
Shannon G. Patel ◽  
Daniel D. Kelson ◽  
Bradford P. Holden ◽  
Marijn Franx ◽  
Garth D. Illingworth
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Star Forming ◽  
Density Relation

scholarly journals Far-Infrared Emission from Clumpy Irregular Galaxies

1987 ◽  
Vol 115 ◽  
pp. 647-647
Author(s):  
U. Klein ◽  
J. Heidmann ◽  
R. Wielebinski ◽  
E. Wunderlich
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Hubble Constant ◽  
Far Infrared ◽  
Hii Regions ◽  
Infrared Emission ◽  
Star Forming ◽  
Irregular Galaxies

The four clumpy irregular galaxies Mkr 8, 296,297 and 325 have been observed by IRAS. All galaxies have been detected in at least two of the four detector bands. The ratios of the 100 to 60-m flux densities are comparable to those of HII regions or violently star forming galaxies. The average star formation rate in clumpy irregular galaxies is of the order of a few solar masses per year (based on their average far-infrared luminosity and a Hubble constant of 75 km s−1 Mpc−1.

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