GLOBAL STAR FORMATION RATES AND DUST EMISSION OVER THE GALAXY INTERACTION SEQUENCE

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.

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Dust properties and star formation of approximately a thousand local galaxies

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834553 ◽

2019 ◽

Vol 631 ◽

pp. A38 ◽

Cited By ~ 1

Author(s):

S. Lianou ◽

P. Barmby ◽

A. A. Mosenkov ◽

M. Lehnert ◽

O. Karczewski

Keyword(s):

Star Formation ◽

Spectral Energy Distribution ◽

Dust Emission ◽

Distribution Functions ◽

Spectral Energy ◽

Emission Properties ◽

Galaxy Type ◽

Dust Mass ◽

The Galaxy ◽

Stellar Masses

Aims. We derived the dust properties for 753 local galaxies and examine how these relate to some of their physical properties. We present the derived dust emission properties, including model spectral energy distribution (SEDs), star formation rates (SFRs) and stellar masses, as well as their relations. Methods. We modelled the global dust-SEDs for 753 galaxies, treated statistically as an ensemble within a hierarchical Bayesian dust-SED modelling approach, so as to derive their infrared (IR) emission properties. To create the observed dust-SEDs, we used a multi-wavelength set of observations, ranging from near-IR to far-IR-to-submillimeter wavelengths. The model-derived properties are the dust masses (Mdust), the average interstellar radiation field intensities (Uav), the mass fraction of very small dust grains (“QPAH” fraction), as well as their standard deviations. In addition, we used mid-IR observations to derive SFR and stellar masses, quantities independent of the dust-SED modelling. Results. We derive distribution functions of the properties for the galaxy ensemble and as a function of galaxy type. The mean value of Mdust for the early-type galaxies (ETGs) is lower than that for the late-type and irregular galaxies (LTGs and Irs, respectively), despite ETGs and LTGs having stellar masses spanning across the whole range observed. The Uav and “QPAH” fraction show no difference among different galaxy types. When fixing Uav to the Galactic value, the derived “QPAH” fraction varies across the Galactic value (0.071). The specific SFR increases with galaxy type, while this is not the case for the dust-specific SFR (SFR/Mdust), showing an almost constant star formation efficiency per galaxy type. The galaxy sample is characterised by a tight relationship between the dust mass and the stellar mass for the LTGs and Irs, while ETGs scatter around this relation and tend towards smaller dust masses. While the relation indicates that Mdust may fundamentally be linked to M⋆, metallicity and Uav are the second parameter driving the scatter, which we investigate in a forthcoming work. We used the extended Kennicutt–Schmidt (KS) law to estimate the gas mass and the gas-to-dust mass ratio (GDR). The gas mass derived from the extended KS law is on average ∼20% higher than that derived from the KS law, and a large standard deviation indicates the importance of the average star formation present to regulate star formation and gas supply. The average GDR for the LTGs and Irs is 370, and including the ETGs gives an average of 550.

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Kinematic asymmetry of galaxy pairs

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319008305 ◽

2019 ◽

Vol 14 (S353) ◽

pp. 262-263

Author(s):

Shuai Feng ◽

Shi-Yin Shen ◽

Fang-Ting Yuan

Keyword(s):

Star Formation ◽

Velocity Field ◽

Star Formation Rate ◽

Formation Rate ◽

Control Sample ◽

Interacting Galaxies ◽

Ionized Gas ◽

Galaxy Interaction ◽

The Galaxy

AbstractThe interaction between galaxies is believed to be the main origin of the peculiarities of galaxies. It can disturb not only the morphology but also the kinematics of galaxies. These disturbed and asymmetric features are the indicators of galaxy interaction. We study the velocity field of ionized gas in galaxy pairs based on MaNGA survey. Using the kinemetry package, we fit the velocity field and quantify the degree of kinematic asymmetry. We find that the fraction of high kinematic asymmetry is much higher for galaxy pairs with dp⩽30h−1kpc. Moreover, compared to a control sample of single galaxies, we find that the star formation rate is enhanced in paired galaxies with high kinematic asymmetry. For paired galaxies with low kinematic asymmetry, no significant SFR enhancement has been found. The galaxy pairs with high kinematic asymmetry are more likely to be real interacting galaxies rather than projected pairs.

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Deeply Embedded Protostellar Population in the Central Molecular Zone Suggested by H2O Masers and Dense Cores

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316012114 ◽

2016 ◽

Vol 11 (S322) ◽

pp. 99-102

Author(s):

Xing Lu ◽

Qizhou Zhang ◽

Jens Kauffmann ◽

Thushara Pillai ◽

Steven N. Longmore ◽

...

Keyword(s):

Star Formation ◽

Dust Emission ◽

High Sensitivity ◽

High Angular Resolution ◽

Physical Conditions ◽

Dense Cores ◽

The Galaxy ◽

Water Masers ◽

Water Maser

AbstractThe Central Molecular Zone (CMZ), usually referring to the inner 500 pc of the Galaxy, contains a dozen of massive (~105M⊙) molecular clouds. Are these clouds going to actively form stars like Sgr B2? How are they affected by the extreme physical conditions in the CMZ, such as strong turbulence? Here we present a first step towards answering these questions. Using high-sensitivity, high angular resolution radio and (sub)millimeter observations, we studied deeply embedded star formation in six massive clouds in the CMZ, including the 20 and 50 km s−1 clouds, Sgr B1 off (as known as dust ridge clouds e/f), Sgr C, Sgr D, and G0.253 – 0.016. The VLA water maser observations suggest a population of deeply embedded protostellar candidates, many of which are new detections. The SMA 1.3 mm continuum observations reveal peaks in dust emission associated with the masers, suggesting the existence of dense cores. While our findings confirm that clouds such as G0.253 – 0.016 lack internal compact substructures and are quiescent in terms of star formation, two clouds (the 20 km s−1 cloud and Sgr C) stand out with clusters of water masers with associated dense cores which may suggest a population of deeply embedded protostars at early evolutionary phases. Follow-up observations with VLA and ALMA are necessary to confirm their protostellar nature.

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Numerical Simulations of Star Formation Bursts Induced by the Galaxy-Galaxy Interaction

Symposium - International Astronomical Union ◽

10.1017/s0074180900096741 ◽

1987 ◽

Vol 115 ◽

pp. 650-653

Author(s):

Masafumi Noguchi ◽

Shiro Ishibashi

Keyword(s):

Star Formation ◽

Kinetic Energy ◽

Supernova Explosion ◽

Particle Model ◽

Disk Galaxies ◽

Triggering Mechanism ◽

Cloud Particle ◽

Test Particles ◽

Galaxy Interaction ◽

The Galaxy

The galaxy-galaxy interaction has been proposed as a possible triggering mechanism of the star formation bursts in some galaxies (e.g. Larson and Tinsley 1978). To investigate the nature of star formation bursts triggered by interaction we have numerically simulated close encounters between disk galaxies, taking the star formation process into account (see Noguchi and Ishibashi 1986 for details). We used the cloud-particle model, in which gas clouds move as test particles in the gravitational field of the galaxies. When two clouds collide with each other, an OB-star is formed. The cloud system loses its kinetic energy by inelastic cloud-cloud collisions. The supernova explosion which follows the formation of an OB-star provides kinetic energy to the nearby clouds.

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Numerical Simulations of Star Formation Bursts Induced by the Galaxy-Galaxy Interaction

Star Forming Regions ◽

10.1007/978-94-009-4782-5_199 ◽

1987 ◽

pp. 650-653

Author(s):

Masafumi Noguchi ◽

Shiro Ishibashi

Keyword(s):

Star Formation ◽

Numerical Simulations ◽

Galaxy Interaction ◽

The Galaxy

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Influence of AGN on the properties of galaxies during the (U)LIRG phase

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313001063 ◽

2012 ◽

Vol 8 (S292) ◽

pp. 193-193

Author(s):

Ming-Yi Lin ◽

Sébastien Foucaud ◽

Yasuhiro Hashimoto

Keyword(s):

Star Formation ◽

Galaxy Formation ◽

Formation Theory ◽

X Ray ◽

Dust Temperature ◽

Cosmic Evolution ◽

Galaxy Interaction ◽

The Galaxy ◽

Multi Wavelength ◽

Luminous Objects

AbstractMerging, resulting from galaxy interaction and collision, is one essential scenario to interpret the distinct evolutionary stages of galaxy formation. However AGNs are believed to play an essential role towards the final stages of this scenario, in particular to clear the galaxy from a large excess of dust. Selecting galaxies with both 70μm and X-ray detection will help to understand the relation between star formation and AGN. We are taking advantage of the extensive multi-wavelength coverage of the Cosmic Evolution Survey (COSMOS) field to dissect the AGN influence on infrared luminous objects. We demonstrate that enhanced star formation is more probably responsible for additional obscuration of the central AGN than the dust torus, in agreement with current galaxy formation theory. Furthermore, we demonstrate that the presence of an AGN does not increase the galaxy dust temperature significantly.

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Jekyll & Hyde: quiescence and extreme obscuration in a pair of massive galaxies 1.5 Gyr after the Big Bang

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731917 ◽

2018 ◽

Vol 611 ◽

pp. A22 ◽

Cited By ~ 21

Author(s):

C. Schreiber ◽

I. Labbé ◽

K. Glazebrook ◽

G. Bekiaris ◽

C. Papovich ◽

...

Keyword(s):

Star Formation ◽

Dust Emission ◽

Rotating Disk ◽

Big Bang ◽

Star Formation History ◽

Massive Galaxies ◽

The Galaxy ◽

Dusty Galaxies ◽

Ir Emission ◽

The Big Bang

We obtained ALMA spectroscopy and deep imaging to investigate the origin of the unexpected sub-millimeter emission toward the most distant quiescent galaxy known to date, ZF-COSMOS-20115 at z = 3.717. We show here that this sub-millimeter emission is produced by another massive (M*~ 1011 M⊙), compact (r1∕2 = 0.67 ± 0.14 kpc) and extremely obscured galaxy (AV ~ 3.5), located only 0.43′′ (3.1 kpc) away from the quiescent galaxy. We dub the quiescent and dusty galaxies Jekyll and Hyde, respectively. No dust emission is detected at the location of the quiescent galaxy, implying SFR < 13 M⊙ yr−1 which is the most stringent upper limit ever obtained for a quiescent galaxy at these redshifts. The two sources are spectroscopically confirmed to lie at the same redshift thanks to the detection of [C II]158 in Hyde (z = 3.709), which provides one the few robust redshifts for a highly-obscured “H-dropout” galaxy (H − [4.5] = 5.1 ± 0.8). The [C II] line shows a clear rotating-disk velocity profile which is blueshifted compared to the Balmer lines of Jekyll by 549 ± 60 km s−1, demonstrating that it is produced by another galaxy. Careful de-blending of the Spitzer imaging confirms the existence of this new massive galaxy, and its non-detection in the Hubble images requires extremely red colors and strong attenuation by dust. Full modeling of the UV-to-far-IR emission of both galaxies shows that Jekyll has fully quenched at least 200Myr prior to observation and still presents a challenge for models, while Hyde only harbors moderate star-formation with SFR ≲ 120 M⊙ yr−1, and is located at least a factor 1.4 below the z ~ 4 main sequence. Hyde could also have stopped forming stars less than 200 Myr before being observed; this interpretation is also suggested by its compactness comparable to that of z ~ 4 quiescent galaxies and its low [C II]/FIR ratio, but significant on-going star-formation cannot be ruled out. Lastly, we find that despite its moderate SFR, Hyde hosts a dense reservoir of gas comparable to that of the most extreme starbursts. This suggests that whatever mechanism has stopped or reduced its star-formation must have done so without expelling the gas outside of the galaxy. Because of their surprisingly similar mass, compactness, environment and star-formation history, we argue that Jekyll and Hyde can be seen as two stages of the same quenching process, and provide a unique laboratory to study this poorly understood phenomenon.

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Survival of molecular gas in a stellar feedback-driven outflow witnessed with the MUSE TIMER project and ALMA

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz1844 ◽

2019 ◽

Vol 488 (3) ◽

pp. 3904-3928 ◽

Cited By ~ 6

Author(s):

Ryan Leaman ◽

Francesca Fragkoudi ◽

Miguel Querejeta ◽

Gigi Y C Leung ◽

Dimitri A Gadotti ◽

...

Keyword(s):

Magnetic Field ◽

Star Formation ◽

Mechanical Energy ◽

Molecular Gas ◽

Ionized Gas ◽

Star Forming ◽

Stellar Feedback ◽

Dominant Component ◽

The Galaxy ◽

Field Lines

ABSTRACT Stellar feedback plays a significant role in modulating star formation, redistributing metals, and shaping the baryonic and dark structure of galaxies – however, the efficiency of its energy deposition to the interstellar medium is challenging to constrain observationally. Here we leverage HST and ALMA imaging of a molecular gas and dust shell ($M_{\mathrm{ H}_2} \sim 2\times 10^{5}\, {\rm M}_{\odot }$) in an outflow from the nuclear star-forming ring of the galaxy NGC 3351, to serve as a boundary condition for a dynamical and energetic analysis of the outflowing ionized gas seen in our MUSE TIMER survey. We use starburst99 models and prescriptions for feedback from simulations to demonstrate that the observed star formation energetics can reproduce the ionized and molecular gas dynamics – provided a dominant component of the momentum injection comes from direct photon pressure from young stars, on top of supernovae, photoionization heating, and stellar winds. The mechanical energy budget from these sources is comparable to low luminosity active galactic neuclei, suggesting that stellar feedback can be a relevant driver of bulk gas motions in galaxy centres – although here ≲10−3 of the ionized gas mass is escaping the galaxy. We test several scenarios for the survival/formation of the cold gas in the outflow, including in situ condensation and cooling. Interestingly, the geometry of the molecular gas shell, observed magnetic field strengths and emission line diagnostics are consistent with a scenario where magnetic field lines aided survival of the dusty ISM as it was initially launched (with mass-loading factor ≲1) from the ring by stellar feedback. This system’s unique feedback-driven morphology can hopefully serve as a useful litmus test for feedback prescriptions in magnetohydrodynamical galaxy simulations.

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Astrophysical MHD turbulence: confluence of observations, simulations, and theory

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313002718 ◽

2012 ◽

Vol 8 (S294) ◽

pp. 325-336 ◽

Cited By ~ 1

Author(s):

Blakesley Burkhart ◽

Alex Lazarian

Keyword(s):

Star Formation ◽

Interstellar Medium ◽

Magnetic Reconnection ◽

Particle Transport ◽

Recent Progress ◽

Critical Component ◽

Dynamo Theory ◽

Mhd Turbulence ◽

The Galaxy

AbstractMagnetohydrodynamic (MHD) turbulence is a critical component of the current paradigms of star formation, dynamo theory, particle transport, magnetic reconnection and evolution of the ISM. In order to gain understanding of how MHD turbulence regulates processes in the Galaxy, a confluence of numerics, observations and theory must be imployed. In these proceedings we review recent progress that has been made on the connections between theoretical, numerical, and observational understanding of MHD turbulence as it applies to both the neutral and ionized interstellar medium.

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