scholarly journals Panchromatic study of the first galaxies with large ALMA programs

2019 ◽  
Vol 15 (S341) ◽  
pp. 12-16 ◽  
Author(s):  
A. Faisst ◽  
M. Béthermin ◽  
P. Capak ◽  
P. Cassata ◽  
O. Le Fèvre ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
High Redshift ◽  
Optical Emission ◽  
Far Infrared ◽  
Photometric Redshifts ◽  
Galaxy Formation And Evolution ◽  
Major Player ◽  
Imaging And Spectroscopy ◽  
First Galaxies ◽  
Stellar Masses

AbstractThanks to deep optical to near-IR imaging and spectroscopy, significant progress is made in characterizing the rest-frame UV to optical properties of galaxies in the early universe (z > 4. Surveys with Hubble, Spitzer, and ground-based facilities (Keck, Subaru, and VLT) provide spectroscopic and photometric redshifts, measurements of the spatial structure, stellar masses, and optical emission lines for large samples of galaxies. Recently, the Atacama Large (Sub) Millimeter Array (ALMA) has become a major player in pushing studies of high redshift galaxies to far-infrared wavelengths, hence making panchromatic surveys over many orders of frequencies possible. While past studies focused mostly on bright sub-millimeter galaxies, the sensitivity of ALMA now enables surveys like ALPINE, which focuses on measuring the gas and dust properties of a large sample of normal main-sequence galaxies at z > 4. Combining observations across different wavelengths into a single, panchromatic picture of galaxy formation and evolution is currently and in the future an important focus of the astronomical community.

scholarly journals Mapping large-scale-structure evolution over cosmic times

2021 ◽  
Author(s):  
Marta B. Silva ◽  
Ely D. Kovetz ◽  
Garrett K. Keating ◽  
Azadeh Moradinezhad Dizgah ◽  
Matthieu Bethermin ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Large Scale ◽  
High Redshift ◽  
Formation Rate ◽  
Far Infrared ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Structure Evolution ◽  
Intensity Mapping ◽  
Wide Range

AbstractThis paper outlines the science case for line-intensity mapping with a space-borne instrument targeting the sub-millimeter (microwaves) to the far-infrared (FIR) wavelength range. Our goal is to observe and characterize the large-scale structure in the Universe from present times to the high redshift Epoch of Reionization. This is essential to constrain the cosmology of our Universe and form a better understanding of various mechanisms that drive galaxy formation and evolution. The proposed frequency range would make it possible to probe important metal cooling lines such as [CII] up to very high redshift as well as a large number of rotational lines of the CO molecule. These can be used to trace molecular gas and dust evolution and constrain the buildup in both the cosmic star formation rate density and the cosmic infrared background (CIB). Moreover, surveys at the highest frequencies will detect FIR lines which are used as diagnostics of galaxies and AGN. Tomography of these lines over a wide redshift range will enable invaluable measurements of the cosmic expansion history at epochs inaccessible to other methods, competitive constraints on the parameters of the standard model of cosmology, and numerous tests of dark matter, dark energy, modified gravity and inflation. To reach these goals, large-scale structure must be mapped over a wide range in frequency to trace its time evolution and the surveyed area needs to be very large to beat cosmic variance. Only a space-borne mission can properly meet these requirements.

scholarly journals Theoretically modelling photoionised regions with fractal geometry in three-dimension

2019 ◽  
Vol 15 (S352) ◽  
pp. 71-72
Author(s):  
Yifei Jin ◽  
Lisa Kewley ◽  
Ralph Sutherland
Keyword(s):  
Monte Carlo ◽  
Emission Line ◽  
Galaxy Formation ◽  
Fractal Geometry ◽  
Complex Geometry ◽  
High Redshift ◽  
Three Dimension ◽  
High Redshift Galaxies ◽  
Monte Carlo Techniques ◽  
Galaxy Formation And Evolution

AbstractAccurate predictions of the physics of interstellar medium (ISM) are vital for understanding galaxy formation and evolution. Modelling photoionized regions with complex geometry produces realistic ionization structures within the nebulae, providing the necessary physical predictions to interpret observational data. 3D photoionization codes built with Monte Carlo techniques provide powerful tools to produce the ionizing radiation field with fractal geometry. We present a high-resolution Monte Carlo modelling of a nebula with fractal geometry, and will further show how nebular geometry influences the emission-line behaviours. Our research has important implications for studies of emission-line ratios in high redshift galaxies.

scholarly journals The potential of using KMOS for multi-object massive star spectroscopy

2016 ◽  
Vol 12 (S329) ◽  
pp. 454-454
Author(s):  
Michael Wegner ◽  
Ralf Bender ◽  
Ray Sharples ◽  
Keyword(s):  
Galaxy Formation ◽  
Near Infrared ◽  
High Redshift ◽  
High Mass ◽  
Galactic Centre ◽  
Star Forming ◽  
Star Forming Regions ◽  
Spectral Bands ◽  
Galaxy Formation And Evolution ◽  
Potential Applications

AbstractKMOS, the “K-Band Multi-Object Spectrometer”, was built by a British-German consortium as a second generation instrument for the ESO Paranal Observatory. It is available to the user community since its successful commissioning in 2013 (Sharples et al. 2013). As a multi-object integral field spectrometer for the near infrared, KMOS offers 24 deployable IFUs of 2.8x2.8 arcsec and 14x14 spatial pixels each, which can either be placed individually within a 7.2 arcmin field of view or combined in a Mosaic mode in order to map contiguous fields on sky. The instrument covers the whole range of NIR atmospheric windows (0.8. . .2.5μm) with 5 spectral bands and a resolution of R ≈ 3000. . .4000.Although the main science driver for KMOS was to enable the study of galaxy formation and evolution through multiplexed observations of high-redshift galaxies, KMOS also already exhibited its tremendous potential for the spectroscopy of massive stars: A quantitative study of 27 RSGs in NGC 300 (Gazak et al. 2015) proves its applicability for the spectroscopy of individual stars even beyond the Local Group. A Mosaic observation of the Galactic centre (Feldmeier-Krause et al. 2015) demonstrates how spectra of early-type stars can be extracted from a contiguous field. Other applications include (but need not be limited to) velocity determinations of globular cluster stars, observations of jets/outflows of high mass protostars, or contiguous mapping of star-forming regions.We therefore aim at presenting the excellent capabilities of KMOS to a wider community and indicate potential applications.

scholarly journals Spatially resolving the relics: The inferring the physics driving the quenching of massive galaxies from kinematics at z ∼ 1 and beyond

2019 ◽  
Vol 15 (S352) ◽  
pp. 267-267
Author(s):  
Rachel Bezanson
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
High Redshift ◽  
Elliptical Galaxies ◽  
Spectroscopic Studies ◽  
Gas Reservoirs ◽  
Massive Galaxies ◽  
Spatially Resolved ◽  
Galaxy Formation And Evolution ◽  
Ordered Motion

AbstractToday's massive elliptical galaxies are primarily red-and-dead, dispersion supported ellipticals. The physical process(es) driving the shutdown or ‘quenching’ of star formation in these galaxies remains one of the least understood aspects of galaxy formation and evolution. Although today's spiral and elliptical galaxies exhibit a clear bimodality in their structures, kinematics, and stellar populations, it may be that the quenching and structural transformation do no occur simultaneously. In this talk I will present evidence that early quiescent galaxies, observed much closer to their quenching epoch at z ∼ 1, retain significant rotational support (∼ twice as much as local ellipticals). This suggests that the mechanisms responsible for shutting down star formation do not also have to destroy ordered motion in massive galaxies; the increased dispersion support could occur subsequently via hierarchical growth and minor merging. I will discuss this evidence in conjunction with recent ALMA studies of the dramatic range in molecular gas reservoirs of recently quenched high redshift galaxies to constrain quenching models. Finally, I will discuss prospects for extending spatially resolved spectroscopic studies of galaxies immediately following quenching with JWST and eventually 30-m class telescopes.

scholarly journals Formation and Evolution of Nucleated Galaxies

2006 ◽  
Vol 2 (S235) ◽  
pp. 172-174
Author(s):  
Kenji Bekki
Keyword(s):  
Galaxy Formation ◽  
Globular Clusters ◽  
High Redshift ◽  
Galaxy Mergers ◽  
Galaxy Formation And Evolution ◽  
Central Regions ◽  
Low Mass ◽  
Formation And Evolution ◽  
Nuclear Structures ◽  
High Redshift Universe

AbstractWe discuss how stellar galactic nuclei (SGN) form and evolve during galaxy formation and evolution based on chemodynamical simulations on the central regions (1-1000 pc) of galaxies. Our simulations demonstrate that dissipative formation of SGN through rapid transfer of gas into the central 10 pc of galaxies is more consistent with recent observations of SGN than dissipationless formation of SGN through merging of globular clusters (GCs). Nuclear structures in the remnants of major galaxy mergers between low-mass, nucleated spirals are found to depend strongly on the mass-ratio of massive black holes (MBHs) to SGN in spirals in the sense that the remnants have more distinct SGN in the mergers with the smaller MBH-to-SGN-mass-ratios. During the destruction of low-mass, nucleated galaxies by strong tidal fields of giant galaxies, SGN can remain intact. The stripped SGN can be observed as bright GCs around the giant galaxies. The color-magnitude relation of metal-poor GCs (referred to as “the blue tilt”) recently discovered for bright galaxies is similar to that of SGN, which suggests that the origin of the blue tilt is closely associated with the formation processes of SGN of gas-rich, low-mass dwarfs in the high redshift universe.

scholarly journals Simulating JWST deep extragalactic imaging surveys and physical parameter recovery

2020 ◽  
Vol 640 ◽  
pp. A67
Author(s):  
O. B. Kauffmann ◽  
O. Le Fèvre ◽  
O. Ilbert ◽  
J. Chevallard ◽  
C. C. Williams ◽  
...  
Keyword(s):  
Star Formation ◽  
Near Infrared ◽  
High Redshift ◽  
Spectral Energy Distribution ◽  
Formation Rate ◽  
Spectral Energy ◽  
Photometric Redshifts ◽  
The Galaxy ◽  
Stellar Masses ◽  
The Impact

We present a new prospective analysis of deep multi-band imaging with the James Webb Space Telescope (JWST). In this work, we investigate the recovery of high-redshift 5 <  z <  12 galaxies through extensive image simulations of accepted JWST programs, including the Early Release Science in the EGS field and the Guaranteed Time Observations in the HUDF. We introduced complete samples of ∼300 000 galaxies with stellar masses of log(M*/M⊙) > 6 and redshifts of 0 <  z <  15, as well as galactic stars, into realistic mock NIRCam, MIRI, and HST images to properly describe the impact of source blending. We extracted the photometry of the detected sources, as in real images, and estimated the physical properties of galaxies through spectral energy distribution fitting. We find that the photometric redshifts are primarily limited by the availability of blue-band and near-infrared medium-band imaging. The stellar masses and star formation rates are recovered within 0.25 and 0.3 dex, respectively, for galaxies with accurate photometric redshifts. Brown dwarfs contaminating the z >  5 galaxy samples can be reduced to < 0.01 arcmin−2 with a limited impact on galaxy completeness. We investigate multiple high-redshift galaxy selection techniques and find that the best compromise between completeness and purity at 5 <  z <  10 using the full redshift posterior probability distributions. In the EGS field, the galaxy completeness remains higher than 50% at magnitudes mUV <  27.5 and at all redshifts, and the purity is maintained above 80 and 60% at z ≤ 7 and 10, respectively. The faint-end slope of the galaxy UV luminosity function is recovered with a precision of 0.1–0.25, and the cosmic star formation rate density within 0.1 dex. We argue in favor of additional observing programs covering larger areas to better constrain the bright end.

scholarly journals UV regulated star formation in high-redshift galaxies

2019 ◽  
Vol 490 (2) ◽  
pp. 2706-2716 ◽  
Author(s):  
Muhammad A Latif ◽  
Sadegh Khochfar
Keyword(s):  
Star Formation ◽  
Galaxy Formation ◽  
Background Radiation ◽  
High Redshift ◽  
Three Dimensional ◽  
Background Level ◽  
Reaction Rates ◽  
Big Bang ◽  
Dense Gas ◽  
First Galaxies

ABSTRACT The first galaxies forming a few hundred million years after the big bang are the key drivers of cosmic evolution and ideal laboratories to study theories of galaxy formation. We here study the role of UV radiation in suppressing star formation in primordial galaxies by destroying molecular hydrogen, the main coolant in primordial gas, and provide estimates of cold dense gas at the onset of star formation. To accomplish this goal, we perform three-dimensional cosmological simulations of minihaloes in different environments forming at z ∼ 25 by varying strength of background UV flux below the Lyman limit between 0.01–1000 in units of $\rm J_{21}=10^{-21}\, erg \,cm^{-2} \,s^{-1} \,Hz^{-1} \,sr^{-1}$. Particularly, we include photodetachment of $\rm H^-$, the self-shielding of $\rm H_2$, which both were neglected in previous studies and use updated reaction rates. Our results show that depending on the background level $\rm H_2$ formation is suppressed, delaying gravitational collapse until haloes reach the atomic cooling limit. We find that the formation of cold dense molecular gas and subsequently star formation gets delayed by 100–230 Myr depending on the level of the background radiation and the growth history of the dark matter haloes. The fraction of dense self-shielded gas is a strong function of the background flux and exponentially declines with the strength of incident UV flux above $\rm J_{21} \ge 1$. We find that taking into account $\rm H_2$ self-shielding is crucial for accurately estimating the amount of cold dense gas available for star formation.

scholarly journals Simulations at the Dwarf Scale: From Violent Dwarfs at Cosmic Dawn and Cosmic Noon to Quiet Discs today

2018 ◽  
Vol 14 (S344) ◽  
pp. 468-472
Author(s):  
Daniel Ceverino
Keyword(s):  
Galaxy Formation ◽  
Mass Scale ◽  
Local Scaling ◽  
James Webb Space Telescope ◽  
Accretion Rates ◽  
Hydrodynamical Simulations ◽  
First Galaxies ◽  
Fisher Relation ◽  
Gas Accretion ◽  
Stellar Masses

AbstractDwarf galaxies with stellar masses around 109M⊙ can be explored at high and low redshifts and they give a glimpse of the different conditions of galaxy formation at different epochs. Using a large sample of about 300 zoom-in cosmological hydrodynamical simulations of galaxy formation I will briefly describe the formation of dwarfs at this mass scale at 3 different epochs: cosmic dawn (Ceverino, Klessen, Glover 2018), cosmic noon (Ceverino, Primack, Dekel 2015), and today (Ceverino et al. 2017). I will describe the FirstLight simulations of first galaxies at redshifts 5-15. These first dwarfs have extremely high star formation efficiencies due to high gas fractions and high gas accretion rates. These simulations will make predictions that will be tested for the first time with the James Webb Space Telescope (JWST). At cosmic noon, z = 2, galaxy formation is still a very violent and dynamic process. The VELA simulations have generated a set of dispersion-dominated dwarfs that show an elongated morphology due to their prolate dark-matter halos. Between z = 1 and 0, the AGORA simulation shows the formation of a low-mass disc due to slow gas accretion. The disc agrees with many local scaling relations, such as the stellar-mass-halo-mass and the baryonic Tully-Fisher relation.

scholarly journals X-ray emission of z > 2.5 active galactic nuclei can be obscured by their host galaxies

2019 ◽  
Vol 623 ◽  
pp. A172 ◽  
Author(s):  
C. Circosta ◽  
C. Vignali ◽  
R. Gilli ◽  
A. Feltre ◽  
F. Vito ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
High Redshift ◽  
Galactic Nuclei ◽  
Far Infrared ◽  
Host Galaxy ◽  
Spectral Energy ◽  
X Rays ◽  
Host Galaxies ◽  
X Ray ◽  
Stellar Masses

We present a multiwavelength study of seven active galactic nuclei (AGN) at spectroscopic redshift >2.5 in the 7 Ms Chandra Deep Field South that were selected for their good far-infrared (FIR) and submillimeter (submm) detections. Our aim is to investigate the possibility that the obscuration observed in the X-rays can be produced by the interstellar medium (ISM) of the host galaxy. Based on the 7 Ms Chandra spectra, we measured obscuring column densities NH,  X in excess of 7 × 1022 cm−2 and intrinsic X-ray luminosities LX >  1044 erg s−1 for our targets, as well as equivalent widths for the Fe Kα emission line EWrest ≳ 0.5−1 keV. We built the UV-to-FIR spectral energy distributions (SEDs) by using broadband photometry from the CANDELS and Herschel catalogs. By means of an SED decomposition technique, we derived stellar masses (M* ∼ 1011 M⊙), IR luminosities (LIR >  1012 L⊙), star formation rates (SFR ∼ 190−1680 M⊙ yr−1) and AGN bolometric luminosities (Lbol ∼ 1046 erg s−1) for our sample. We used an empirically calibrated relation between gas masses and FIR/submm luminosities and derived Mgas ∼ 0.8−5.4 × 1010 M⊙. High-resolution (0.3−0.7″) ALMA data (when available, CANDELS data otherwise) were used to estimate the galaxy size and hence the volume enclosing most of the ISM under simple geometrical assumptions. These measurements were then combined to derive the column density associated with the ISM of the host, which is on the order of NH,  ISM ∼ 1023−24 cm−2. The comparison between the ISM column densities and those measured from the X-ray spectral analysis shows that they are similar. This suggests that at least at high redshift, significant absorption on kiloparsec scales by the dense ISM in the host likely adds to or substitutes that produced by circumnuclear gas on parsec scales (i.e., the torus of unified models). The lack of unobscured AGN among our ISM-rich targets supports this scenario.

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