scholarly journals Lessons on early structure formation from a mature galaxy cluster observed at cosmic noon

2020 ◽  
Vol 495 (2) ◽  
pp. 1700-1705
Author(s):  
Boyuan Liu ◽  
Anna T P Schauer ◽  
Volker Bromm
Keyword(s):  
Star Formation ◽  
Structure Formation ◽  
Hubble Space Telescope ◽  
Age Distribution ◽  
Rapid Evolution ◽  
Galaxy Cluster ◽  
Starburst Galaxies ◽  
Boson Mass ◽  
First Stars ◽  
Low Mass

ABSTRACT We demonstrate a new approach of indirectly constraining both early star and structure formation via mature galaxy clusters at cosmic noon (z ∼ 2), using the cluster XLSSC 122 as an example. With the standard Press Schechter formalism, we infer a rapid evolution of the star formation efficiency (the ratio of stellar to halo mass) from 10−4 to 0.01 during z ∼ 20−13, based on the age distribution of stars in post-starburst galaxies of XLSSC 122, measured by Hubble Space Telescope photometry assuming no dust extinction. Here, we consider all low-mass haloes, including minihaloes, that host the first stars and galaxies ($5\times 10^5\ \rm M_{\odot }\lesssim M_{\rm halo}\lesssim 10^{10}\ \rm M_{\odot }$). We also place new constraints on fuzzy dark matter models of ma ≲ 5 × 10−21 eV/c2 for the ultralight boson mass, from the abundance of galaxies with star formation at z ≳ 13 in XLSSC 122. Our exploratory results are consistent with existing constraints. More comprehensive results will be obtained if our approach is extended to a large sample of clusters or field post-starburst galaxies at cosmic noon, with improved modelling of halo and stellar populations.

scholarly journals Young and intermediate-age massive star clusters

2010 ◽  
Vol 368 (1913) ◽  
pp. 867-887 ◽  
Author(s):  
Søren S. Larsen
Keyword(s):  
Star Formation ◽  
Star Clusters ◽  
Mass Function ◽  
Starburst Galaxies ◽  
Open Clusters ◽  
High Mass ◽  
Current Evidence ◽  
Power Law Distribution ◽  
Low Mass ◽  
Massive Clusters

An overview of our current understanding of the formation and evolution of star clusters is given, with the main emphasis on high-mass clusters. Clusters form deeply embedded within dense clouds of molecular gas. Left-over gas is cleared within a few million years and, depending on the efficiency of star formation, the clusters may disperse almost immediately or remain gravitationally bound. Current evidence suggests that a small percentage of star formation occurs in clusters that remain bound, although it is not yet clear whether this fraction is truly universal. Internal two-body relaxation and external shocks will lead to further, gradual dissolution on time scales of up to a few hundred million years for low-mass open clusters in the Milky Way, while the most massive clusters (>10 5  M ⊙ ) have lifetimes comparable to or exceeding the age of the Universe. The low-mass end of the initial cluster mass function is well approximated by a power-law distribution, , but there is mounting evidence that quiescent spiral discs form relatively few clusters with masses M >2×10 5  M ⊙ . In starburst galaxies and old globular cluster systems, this limit appears to be higher, at least several ×10 6  M ⊙ . The difference is likely related to the higher gas densities and pressures in starburst galaxies, which allow denser, more massive giant molecular clouds to form. Low-mass clusters may thus trace star formation quite universally, while the more long-lived, massive clusters appear to form preferentially in the context of violent star formation.

scholarly journals The distribution of dark matter and gas spanning 6 Mpc around the post-merger galaxy cluster MS 0451−03

2020 ◽  
Vol 496 (3) ◽  
pp. 4032-4050 ◽  
Author(s):  
Sut-Ieng Tam ◽  
Mathilde Jauzac ◽  
Richard Massey ◽  
David Harvey ◽  
Dominique Eckert ◽  
...  
Keyword(s):  
Dark Matter ◽  
Star Formation ◽  
Hubble Space Telescope ◽  
Excess Entropy ◽  
Galaxy Cluster ◽  
Formation Processes ◽  
Matter Distribution ◽  
Future Studies ◽  
Major Merger ◽  
Dark Matter Distribution

ABSTRACT Using the largest mosaic of Hubble Space Telescope images around a galaxy cluster, we map the distribution of dark matter throughout an ∼6 × 6 Mpc2 area centred on the cluster MS 0451−03 (z = 0.54, $M_{200}=1.65\times 10^{15}\, {\rm M}_{\odot }$). Our joint strong- and weak-lensing analysis shows three possible filaments extending from the cluster, encompassing six group-scale substructures. The dark matter distribution in the cluster core is elongated, consists of two distinct components, and is characterized by a concentration parameter of c200 = 3.79 ± 0.36. By contrast, XMM–Newton observations show the gas distribution to be more spherical, with excess entropy near the core, and a lower concentration of $c_{200}=2.35^{+0.89}_{-0.70}$ (assuming hydrostatic equilibrium). Such a configuration is predicted in simulations of major mergers 2–7 Gyr after the first core passage, when the two dark matter haloes approach second turnaround, and before their gas has relaxed. This post-merger scenario finds further support in optical spectroscopy of the cluster’s member galaxies, which shows that star formation was abruptly quenched 5 Gyr ago. MS 0451−03 will be an ideal target for future studies of the growth of structure along filaments, star formation processes after a major merger, and the late-stage evolution of cluster collisions.

scholarly journals Clustered Star Formation in the Magellanic Clouds

2007 ◽  
Vol 3 (S246) ◽  
pp. 61-62
Author(s):  
Dimitrios A. Gouliermis
Keyword(s):  
Star Formation ◽  
Hubble Space Telescope ◽  
Magellanic Clouds ◽  
Initial Mass Function ◽  
Star Formation History ◽  
Wide Field ◽  
Space Telescope ◽  
Low Mass ◽  
Pms Stars ◽  
The Impact

AbstractThe Large and Small Magellanic Cloud (LMC, SMC) offer an outstanding variety of young stellar associations, in which large samples of low-mass stars (withM≤ 1 M⊙) currently in the act of formation can be resolved and explored sufficiently with theHubble Space Telescope. Previous observations with theWide-Field Planetary Camera 2(WFPC2) provided the first evidence of the existence of low-mass pre-main sequence (PMS) stars in the vicinity of star forming associations in the Magellanic Clouds (MCs) (Gouliermiset al. 2006a), and recent results from deeper observations with theAdvanced Camera for Surveys(ACS) enhanced dramatically the picture of these systems with the discovery of large numbers of PMS stars. The associations LH 95 (Gouliermiset al. 2002, 2007a) in the LMC, and NGC 346 (Gouliermiset al. 2006b) and NGC 602 (Gouliermiset al. 2007b) in the SMC, are currently under investigation with the use of observations from bothHubbleandSpitzer Space Telescope. I present the impact of our recent results in terms of the star formation history and Initial Mass Function (IMF) of these interesting systems, using as example the case of NGC 602.

scholarly journals Star Formation as Seen by Low Mass Stars

2014 ◽  
Vol 1 (1) ◽  
pp. 113-117
Author(s):  
Nino Panagia ◽  
Guido De Marchi
Keyword(s):  
Star Formation ◽  
Physical Properties ◽  
Main Sequence ◽  
Hubble Space Telescope ◽  
Ongoing Study ◽  
Low Mass Stars ◽  
Homogeneous Sample ◽  
Wide Range ◽  
Low Mass ◽  
Pms Stars

Using the Hubble Space Telescope (HST) we have characterised and compared the physical properties of a large sample of pre-main sequence (PMS) stars spanning a wide range of masses (0:5 - 4M<sub>ʘ</sub>), metallicities (0:1 - 1 Z<sub>ʘ</sub>) and ages (0:5 - 30 Myr). This is presently the largest and most homogeneous sample of PMS objects with known physical properties. The main results of this ongoing study are briefly summarised here.

scholarly journals The Galactic interstellar medium: foregrounds and star formation

2017 ◽  
Vol 12 (S333) ◽  
pp. 138-145
Author(s):  
Marc-Antoine Miville-Deschênes
Keyword(s):  
Star Formation ◽  
Interstellar Medium ◽  
Structure Formation ◽  
Statistical Properties ◽  
Line Of Sight ◽  
First Stars ◽  
Atomic Gas ◽  
Multi Phase

AbstractThis review presents briefly two aspects of Galactic interstellar medium science that seem relevant for studying EoR. First, we give some statistical properties of the Galactic foreground emission in the diffuse regions of the sky. The properties of the emission observed in projection on the plane of the sky are then related to how matter is organised along the line of sight. The diffuse atomic gas is multi-phase, with dense filamentary structures occupying only about 1% of the volume but contributing to about 50% of the emission. The second part of the review presents aspect of structure formation in the Galactic interstellar medium that could be relevant for the subgrid physics used to model the formation of the first stars.

scholarly journals Dissecting the stellar content of Leo I: A dwarf irregular caught in transition

2020 ◽  
Author(s):  
T Ruiz-Lara ◽  
C Gallart ◽  
M Monelli ◽  
T K Fritz ◽  
G Battaglia ◽  
...  
Keyword(s):  
Star Formation ◽  
Hubble Space Telescope ◽  
Star Formation History ◽  
Stellar Content ◽  
Mass System ◽  
Star Forming ◽  
Formation History ◽  
Low Metallicity ◽  
Low Mass ◽  
Gaseous Star

Abstract Leo I is considered one of the youngest dwarf spheroidals (dSph) in the Local Group. Its isolation, extended star formation history (SFH), and recent perigalacticon passage (∼1 Gyr ago) make Leo I one of the most interesting nearby stellar systems. Here, we analyse deep photometric Hubble Space Telescope data via colour-magnitude diagram fitting techniques to study its global and radially-resolved SFH. We find global star formation enhancements in Leo I ∼13, 5.5, 2.0, and 1.0 Gyr ago, after which it was substantially quenched. Within the context of previous works focused on Leo I, we interpret the most ancient and the youngest ones as being linked to an early formation (surviving reionisation) and the latest perigalacticon passage (transition from dIrr to dSph), respectively. We clearly identify the presence of very metal poor stars ([Fe/H] ∼ −2) ageing ∼5–6 and ∼13 Gyr old. We speculate with the possibility that this metal-poor population in Leo I is related to the merging with a low mass system (possibly an ultra-faint dwarf). This event would have triggered star formation (peak of star formation ∼5.5 Gyr ago) and accumulated old, metal poor stars from the accreted system in Leo I. Some of the stars born during this event would also form from accreted gas of low-metallicity (giving rise to the 5-6 Gyr low-metallicity tail). Given the intensity and extension of the 2.0 Gyr burst, we hypothesise that this enhancement could also have an external origin. Despite the quenching of star formation around 1 Gyr ago (most probably induced by ram pressure stripping with the Milky Way halo at pericentre), we report the existence of stars as young as 300-500 Myr. We also distinguish two clear spatial regions: the inner ∼190 pc presents an homogeneous stellar content (size of the gaseous star forming disc in Leo I from ∼4.5 to 1 Gyr ago), whereas the outer regions display a clear positive age gradient.

Low‐Mass Star Formation and the Initial Mass Function in IC 348

1998 ◽  
Vol 508 (1) ◽  
pp. 347-369 ◽  
Author(s):  
K. L. Luhman ◽  
G. H. Rieke ◽  
C. J. Lada ◽  
E. A. Lada
Keyword(s):  
Star Formation ◽  
Mass Function ◽  
Initial Mass Function ◽  
Initial Mass ◽  
Mass Star ◽  
Low Mass

scholarly journals On the emergent system mass function: the contest between accretion and fragmentation

2020 ◽  
Vol 500 (2) ◽  
pp. 1697-1707
Author(s):  
Paul C Clark ◽  
Anthony P Whitworth
Keyword(s):  
Star Formation ◽  
Standard Deviation ◽  
Mass Distribution ◽  
Power Law ◽  
Accretion Rate ◽  
Mass Function ◽  
High Mass ◽  
New Model ◽  
System Formation ◽  
Low Mass

ABSTRACT We propose a new model for the evolution of a star cluster’s system mass function (SMF). The model involves both turbulent fragmentation and competitive accretion. Turbulent fragmentation creates low-mass seed proto-systems (i.e. single and multiple protostars). Some of these low-mass seed proto-systems then grow by competitive accretion to produce the high-mass power-law tail of the SMF. Turbulent fragmentation is relatively inefficient, in the sense that the creation of low-mass seed proto-systems only consumes a fraction, ${\sim }23{{\ \rm per\ cent}}$ (at most ${\sim }50{{\ \rm per\ cent}}$), of the mass available for star formation. The remaining mass is consumed by competitive accretion. Provided the accretion rate on to a proto-system is approximately proportional to its mass (dm/dt ∝ m), the SMF develops a power-law tail at high masses with the Salpeter slope (∼−2.3). If the rate of supply of mass accelerates, the rate of proto-system formation also accelerates, as appears to be observed in many clusters. However, even if the rate of supply of mass decreases, or ceases and then resumes, the SMF evolves homologously, retaining the same overall shape, and the high-mass power-law tail simply extends to ever higher masses until the supply of gas runs out completely. The Chabrier SMF can be reproduced very accurately if the seed proto-systems have an approximately lognormal mass distribution with median mass ${\sim } 0.11 \, {\rm M}_{\odot }$ and logarithmic standard deviation $\sigma _{\log _{10}({M/M}_\odot)}\sim 0.47$).

scholarly journals How robustly can we constrain the low-mass end of the z ∼ 6−7 stellar mass function? The limits of lensing models and stellar population assumptions in the Hubble Frontier Fields

2020 ◽  
Vol 501 (2) ◽  
pp. 1568-1590
Author(s):  
Lukas J Furtak ◽  
Hakim Atek ◽  
Matthew D Lehnert ◽  
Jacopo Chevallard ◽  
Stéphane Charlot
Keyword(s):  
Star Formation ◽  
Mass Function ◽  
Stellar Mass ◽  
Star Formation History ◽  
Space Telescope ◽  
Formation History ◽  
Low Mass ◽  
Stellar Masses ◽  
Dust Attenuation ◽  
The Impact

ABSTRACT We present new measurements of the very low mass end of the galaxy stellar mass function (GSMF) at z ∼ 6−7 computed from a rest-frame ultraviolet selected sample of dropout galaxies. These galaxies lie behind the six Hubble Frontier Field clusters and are all gravitationally magnified. Using deep Spitzer/IRAC and Hubble Space Telescope imaging, we derive stellar masses by fitting galaxy spectral energy distributions and explore the impact of different model assumptions and parameter degeneracies on the resulting GSMF. Our sample probes stellar masses down to $M_{\star }\gt 10^{6}\, \text{M}_{\odot}$ and we find the z ∼ 6−7 GSMF to be best parametrized by a modified Schechter function that allows for a turnover at very low masses. Using a Monte Carlo Markov chain analysis of the GSMF, including accurate treatment of lensing uncertainties, we obtain a relatively steep low-mass end slope $\alpha \simeq -1.96_{-0.08}^{+0.09}$ and a turnover at $\log (M_T/\text{M}_{\odot})\simeq 7.10_{-0.56}^{+0.17}$ with a curvature of $\beta \simeq 1.00_{-0.73}^{+0.87}$ for our minimum assumption model with constant star formation history (SFH) and low dust attenuation, AV ≤ 0.2. We find that the z ∼ 6−7 GSMF, in particular its very low mass end, is significantly affected by the assumed functional form of the star formation history and the degeneracy between stellar mass and dust attenuation. For example, the low-mass end slope ranges from $\alpha \simeq -1.82_{-0.07}^{+0.08}$ for an exponentially rising SFH to $\alpha \simeq -2.34_{-0.10}^{+0.11}$ when allowing AV of up to 3.25. Future observations at longer wavelengths and higher angular resolution with the James Webb Space Telescope are required to break these degeneracies and to robustly constrain the stellar mass of galaxies on the extreme low-mass end of the GSMF.

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.

Sign in / Sign up

Export Citation Format

Share Document