scholarly journals Uncovering the spatial distribution of stars and dust in z ∼ 2 Submillimeter Galaxies

2019 ◽  
Vol 15 (S352) ◽  
pp. 274-279
Author(s):  
Philipp Lang ◽  
Eva Schinnerer ◽  
Ian Smail ◽  
U. Dudzevičiūtė ◽  
A. M. Swinbank ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Star Formation ◽  
High Redshift ◽  
Dust Emission ◽  
Stellar Mass ◽  
Formation Mechanisms ◽  
Galaxy Interactions ◽  
Mass Distributions ◽  
Correction Technique ◽  
Dust Distribution

AbstractThe spatial distribution of the dust and stars contains crucial information about the evolutionary pathways of galaxies. We present results of our study combing high-resolution ALMA and HST observations of z ∼ 2 bright sub-millimeter galaxies (SMGs). We have developed a two-dimensional extinction and age correction technique to obtain accurate stellar mass distributions from HST/CANDELS. For the first time, we can directly compare the spatial distribution of assembled stellar mass and ongoing star formation on kpc scales for distant SMGs, shedding light on their highly debated formation mechanisms. We find that the dust distribution is more compact than the stellar component, regardless if the SMG lies on the main sequence or at the starburst regime. Taking the dust emission as a proxy for dust-obscured star formation, our results imply that high-redshift SMGs are experiencing centrally enhanced star formation. These findings suggests that major galaxy interactions are not necessarily the main formation channel for SMGs with secular disk formation remaining a viable option as suggested by state-of-the-art cosmological simulations. The sizes and stellar densities of our z ∼ 2 SMGs agree well with the most compact early-type galaxies in the local Universe, strongly supporting the idea that the latter systems are indeed the descendants of massive SMGs at z ∼ 2.

scholarly journals Planck’s dusty GEMS

2018 ◽  
Vol 620 ◽  
pp. A60 ◽  
Author(s):  
R. Cañameras ◽  
N. P. H. Nesvadba ◽  
M. Limousin ◽  
H. Dole ◽  
R. Kneissl ◽  
...  
Keyword(s):  
Star Formation ◽  
Near Infrared ◽  
Infrared Imaging ◽  
High Redshift ◽  
Dust Emission ◽  
Galaxy Cluster ◽  
Star Forming ◽  
The Galaxy ◽  
Mass Outflow ◽  
Gas Accretion

We report the discovery of a molecular wind signature from a massive intensely star-forming clump of a few 109 M⊙, in the strongly gravitationally lensed submillimeter galaxy “the Emerald” (PLCK_G165.7+49.0) at z = 2.236. The Emerald is amongst the brightest high-redshift galaxies on the submillimeter sky, and was initially discovered with the Planck satellite. The system contains two magnificient structures with projected lengths of 28.5″ and 21″ formed by multiple, near-infrared arcs, falling behind a massive galaxy cluster at z = 0.35, as well as an adjacent filament that has so far escaped discovery in other wavebands. We used HST/WFC3 and CFHT optical and near-infrared imaging together with IRAM and SMA interferometry of the CO(4–3) line and 850 μm dust emission to characterize the foreground lensing mass distribution, construct a lens model with LENSTOOL, and calculate gravitational magnification factors between 20 and 50 in most of the source. The majority of the star formation takes place within two massive star-forming clumps which are marginally gravitationally bound and embedded in a 9 × 1010 M⊙, fragmented disk with 20% gas fraction. The stellar continuum morphology is much smoother and also well resolved perpendicular to the magnification axis. One of the clumps shows a pronounced blue wing in the CO(4–3) line profile, which we interpret as a wind signature. The mass outflow rates are high enough for us to suspect that the clump might become unbound within a few tens of Myr, unless the outflowing gas can be replenished by gas accretion from the surrounding disk. The velocity offset of –200 km s−1 is above the escape velocity of the clump, but not that of the galaxy overall, suggesting that much of this material might ultimately rain back onto the galaxy and contribute to fueling subsequent star formation.

scholarly journals The relationship between masers and massive star formation: what can be learned from the infrared?

2002 ◽  
Vol 206 ◽  
pp. 18-21 ◽  
Author(s):  
James M. De Buizer
Keyword(s):  
Star Formation ◽  
Accretion Disks ◽  
Massive Star ◽  
Near Infrared ◽  
Dust Emission ◽  
Thermal Infrared ◽  
Dense Medium ◽  
Maser Emission ◽  
Dust Distribution ◽  
The Relationship

The infrared represents an alternative wavelength regime in which to study the environments of maser emission, while at the same time complementing the information obtained through radio techniques. The near infrared (1–2 μm) yields information on outflows, shocks, and reflected dust emission, while the thermal infrared (3–30 μm) yields information on the thermal dust distribution around stars. Thus, the infrared regime yields important clues in determining whether masers exist in shocks, outflows, circumstellar accretion disks, or in the dense medium close to protostars.

scholarly journals Evolution of Massive Galaxy Structural Properties and Sizes via Star Formation

2012 ◽  
Vol 10 (H16) ◽  
pp. 128-128
Author(s):  
Jamie R. Ownsworth ◽  
Christopher J. Conselice ◽  
Alice Mortlock ◽  
William G. Hartley ◽  
Fernando Buitrago
Keyword(s):  
Star Formation ◽  
Rest Frame ◽  
High Redshift ◽  
Formation Rate ◽  
Stellar Mass ◽  
Massive Galaxies ◽  
Mass Profile ◽  
Individual Galaxy ◽  
Mass Profiles

We investigate the resolved star formation properties of a sample of 45 massive galaxies (M* > 1011 M⊙) within a redshift range of 1.5 ⩽ z ⩽ 3 detected in the GOODS NICMOS Survey (Conselice et al. 2011), a HST H160-band imaging program. We derive the star formation rate as a function of radius using rest frame UV data from deep z850 ACS imaging. The star formation present at high redshift is then extrapolated to z = 0, and we examine the stellar mass produced in individual regions within each galaxy. We also construct new stellar mass profiles of the in situ stellar mass at high redshift from Sérsic fits to rest-frame optical, H160-band, data. We combine the two stellar mass profiles to produce an evolved stellar mass profile. We then fit a new Sérsic profile to the evolved profile, from which we examine what effect the resulting stellar mass distribution added via star formation has on the structure and size of each individual galaxy.

scholarly journals Which Galaxy Property Best Predicts Quiescence?

2012 ◽  
Vol 8 (S295) ◽  
pp. 177-177
Author(s):  
Joel Leja ◽  
Pieter van Dokkum ◽  
Keyword(s):  
Spatial Distribution ◽  
Star Formation ◽  
Velocity Dispersion ◽  
High Redshift ◽  
Line Emission ◽  
Elliptical Galaxies ◽  
High Dispersion ◽  
Quenching Mechanism ◽  
Line Flux ◽  
Line Equivalent Width

AbstractIt is generally accepted that local elliptical galaxies assembled most of their mass in a burst of star formation between 1 < z < 3, yet today, their star formation has been almost entirely quenched. In order to constrain this quenching mechanism, we measure Hα line emission in galaxies sorted by multiple galaxy properties as a function of redshift to what galaxy parameter best predicts quiescence. This is done for samples of the most massive, most luminous, and galaxies with the highest velocity dispersion both locally (0.05 < z < 0.07 in the SDSS) and at high redshift (0.7 < z < 1.5 in 3D-HST). It is demonstrated through spectral stacking that velocity dispersion results in the lowest Hα line equivalent width both locally and at high redshift. The spatial distribution of the emission line flux is available from grism spectroscopy: the line flux from the high dispersion stack is centrally peaked and thus likely associated with AGN activity rather than star formation, strengthening this conclusion. Since velocity dispersion may also be the best predictor of halo mass (Wake et al. 2012), this may imply that the quenching mechanism is directly related to halo mass.

scholarly journals THE STAR FORMATION HISTORIES OF EARLY-TYPE GALAXIES: INSIGHTS FROM THE REST-FRAME ULTRAVIOLET

2008 ◽  
Vol 23 (03) ◽  
pp. 153-167 ◽  
Author(s):  
SUGATA KAVIRAJ
Keyword(s):  
Star Formation ◽  
Rest Frame ◽  
High Redshift ◽  
Stellar Mass ◽  
Early Type ◽  
Redshift Range ◽  
Colour Distribution ◽  
Type Population ◽  
Minor Mergers ◽  
Star Formation Histories

Our current understanding of the star formation histories of early-type galaxies is reviewed, in the context of recent observational studies of their ultraviolet (UV) properties. Combination of UV and optical spectro-photometric data indicates that the bulk of the stellar mass in the early-type population forms at high redshift (z>2), possibly over short timescales (<1 Gyr). Nevertheless, early-types of all luminosities form stars over the lifetime of the Universe, with most luminous (-23<M(V)<-21) systems forming 10–15% of their stellar mass after z = 1 (with a scatter to higher value), while their less luminous (M(V)>-21) counterparts form 30–60% of their mass in the same redshift range. The large scatter in the (rest-frame) UV colours in the redshift range 0<z<0.7 indicates widespread low-level star formation in the early-type population over the last 8 billion years. The mass fraction of young (<1 Gyr old) stars in luminous early-type galaxies varies between 1% and 6% at z ~ 0 and is in the range 5–13% at z ~ 0.7. The intensity of recent star formation and the bulk of the UV colour distribution is consistent with what might be expected from minor mergers (mass ratios ≲ 1:6) in a ΛCDM cosmology.

scholarly journals GOODS-Herschel: Dust attenuation up to z∼4

2012 ◽  
Vol 8 (S292) ◽  
pp. 289-289 ◽  
Author(s):  
M. Pannella ◽  
D. Elbaz ◽  
E. Daddi
Keyword(s):  
Star Formation ◽  
High Redshift ◽  
Line Emission ◽  
Stellar Mass ◽  
Massive Galaxies ◽  
Star Forming ◽  
Main Driver ◽  
Galaxy Sample ◽  
Stellar Masses ◽  
Dust Attenuation

AbstractWe quantitatively explore in a unbiased way the evolution of dust attenuation up to z ≈ 4 as a function of galaxy properties. We have used one of the deepest datasets available at present, in the GOODS-N field, to select a star forming galaxy sample and robustly measure galaxy redshifts, star formation rates, stellar masses and UV restframe properties. Our main results can be summarized as follows: i) we confirm that galaxy stellar mass is a main driver of UV dust attenuation in star forming galaxies: more massive galaxies are more dust attenuated than less massive ones; ii) strikingly, we find that the correlation does not evolve with redshift: the amount of dust attenuation is the same at all cosmic epochs for a fixed stellar mass; iii) this finding explains why and how the SFR–AUV relation evolves with redshift: the same amount of star formation is less attenuated at higher redshift because it is hosted in less massive galaxies; iv) combining our finding with results from line emission surveys, we confirm that line reddening is larger than continuum reddening, at least up to z ≈ 1.5; v) given the redshift evolution of the mass-metallicity relation, we predict that star forming galaxies at a fixed metal content are more attenuated at high redshift. Finally, we explored the correlation between UV dust attenuation and the spectral slope: vi) the correlation is evolving with redshift with star forming galaxies at lower redshift having redder spectra than higher redshift ones for the same amount of dust attenuation.

scholarly journals The VLT-FLAMES Tarantula Survey

2018 ◽  
Vol 618 ◽  
pp. A73 ◽  
Author(s):  
F. R. N. Schneider ◽  
O. H. Ramírez-Agudelo ◽  
F. Tramper ◽  
J. M. Bestenlehner ◽  
N. Castro ◽  
...  
Keyword(s):  
Star Formation ◽  
Massive Star ◽  
Massive Stars ◽  
High Redshift ◽  
Large Magellanic Cloud ◽  
Giant Molecular Clouds ◽  
Stellar Content ◽  
Massive Star Formation ◽  
Hii Region ◽  
Mass Distributions

The 30 Doradus (30 Dor) nebula in the Large Magellanic Cloud (LMC) is the brightest HII region in the Local Group and a prototype starburst similar to those found in high redshift galaxies. It is thus a stepping stone to understand the complex formation processes of stars in starburst regions across the Universe. Here, we have studied the formation history of massive stars in 30 Dor using masses and ages derived for 452 mainly OB stars from the spectroscopic VLT-FLAMES Tarantula Survey (VFTS). We find that stars of all ages and masses are scattered throughout 30 Dor. This is remarkable because it implies that massive stars either moved large distances or formed independently over the whole field of view in relative isolation. We find that both channels contribute to the 30 Dor massive star population. Massive star formation rapidly accelerated about 8 Myr ago, first forming stars in the field before giving birth to the stellar populations in NGC 2060 and NGC 2070. The R136 star cluster in NGC 2070 formed last and, since then, about 1 Myr ago, star formation seems to be diminished with some continuing in the surroundings of R136. Massive stars within a projected distance of 8 pc of R136 are not coeval but show an age range of up to 6 Myr. Our mass distributions are well populated up to 200 M⊙. The inferred IMF is shallower than a Salpeter-like IMF and appears to be the same across 30 Dor. By comparing our sample of stars to stellar models in the Hertzsprung–Russell diagram, we find evidence for missing physics in the models above log L/L⊙ = 6 that is likely connected to enhanced wind mass loss for stars approaching the Eddington limit. Our work highlights the key information about the formation, evolution and final fates of massive stars encapsulated in the stellar content of 30 Dor, and sets a new benchmark for theories of massive star formation in giant molecular clouds.

scholarly journals The roles of atomic and molecular gas on the redshift evolution of star formation and metallicity in galaxy formation models

2012 ◽  
Vol 8 (S292) ◽  
pp. 245-245
Author(s):  
Jian Fu ◽  
Guinevere Kauffmann
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Time Scale ◽  
High Redshift ◽  
Formation Rate ◽  
Stellar Mass ◽  
Formation Time ◽  
Model Parameters ◽  
Molecular Gas ◽  
Mass Relation

AbstractWe study the redshift evolution of neutral and molecular gas in the interstellar medium with the results from semi-analytic models of galaxy formation and evolution, which track the cold gas related physical processes in radially resolved galaxy disks. Two kinds of prescriptions are adopted to describe the conversion between molecular and neutral gas in the ISM: one is related to the gas surface density and gas metallicity based on the model results by Krumholz, Mckee & Tumlinson; the other is related the pressure of ISM. We try four types of star formation laws in the models to study the effect of the molecular gas component and the star formation time scale on the model results, and find that the H2 dependent star formation rate with constant star formation efficiency is the preferred star formation law. We run the models based on both Millennium and Millennium II Simulation haloes, and the model parameters are adjusted to fit the observations at z = 0 from THINGS/HERACLES and ALFALFA/COLD GASS. We give predictions for the redshift evolution of cosmic star formation density, H2 to HI cosmic ratios, gas to star mass ratios and gas metallicity vs stellar mass relation. Based on the model results, we find that: (i) the difference in the H2 to HI ratio at z > 3 between the two H2 fraction prescriptions can help future observations to test which prescription is better; (ii) a constant redshift independent star formation time scale will postpone the star formation processes at high redshift and cause obvious redshift evolution for the relation between gas metallicity and stellar mass in galaxies at z < 3.

scholarly journals Mid-IR Spectroscopy of Submm Galaxies: Extended Star Formation in High-z Galaxies

2009 ◽  
Vol 5 (H15) ◽  
pp. 423-424
Author(s):  
K. Menéndez-Delmestre ◽  
A. W. Blain ◽  
I. Smail ◽  
D. M. Alexander ◽  
S. C. Chapman ◽  
...  
Keyword(s):  
Star Formation ◽  
High Redshift ◽  
Dust Emission ◽  
Infrared Galaxies ◽  
Local Universe ◽  
Star Forming ◽  
Luminous Infrared Galaxies ◽  
Star Formation Activity ◽  
Polycyclic Aromatic ◽  
Intense Star Formation

AbstractUltra-luminous infrared galaxies (ULIRGs; L > 1012 L⊙) are quite rare in the local universe, but seem to dominate the co-moving energy density at z > 2. Many are optically-faint, dust-obscured galaxies that have been identified only relatively recently by the detection of their thermal dust emission redshifted into the sub-mm wavelengths. These submm galaxies (SMGs) have been shown to be a massive objects (M* ~ 1011 M⊙) undergoing intense star-formation(SFRs ~ 102 − 103 M⊙ yr−1) and the likely progenitors of massive ellipticals today. However, the AGN contribution to the far-IR luminosity had for years remained a caveat to these results. We used the Spitzer Infrared Spectrograph (IRS) to investigate the energetics of 24 radio-identified and spectroscopically-confirmed SMGs in the redshift range of 0.6 < z < 3.2. We find emission from Polycyclic Aromatic Hydrocarbons (PAHs) – which are associated with intense star-formation activity – in >80% of our sample and find that the median mid-IR spectrum is well described by a starburst component with an additional power-law continuum representing < 32% AGN contribution to the far-IR luminosity. We also find evidence for a more extended distribution of warm dust in SMGs compared to the more compact nuclear bursts in local ULIRGs and starbursts, suggesting that SMGs are not simple high-redshift analogs of local ULIRGs or nuclear starbursts, but have star formation which resembles that seen in less-extreme star-forming environments at z ~ 0.

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