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  • 1
    In: The Astrophysical Journal Letters, American Astronomical Society, Vol. 946, No. 1 ( 2023-03-01), p. L15-
    Kurzfassung: We present a comprehensive analysis of the evolution of the morphological and structural properties of a large sample of galaxies at z = 3–9 using early James Webb Space Telescope (JWST) CEERS NIRCam observations. Our sample consists of 850 galaxies at z 〉 3 detected in both Hubble Space Telescope (HST)/WFC3 and CEERS JWST/NIRCam images, enabling a comparison of HST and JWST morphologies. We conduct a set of visual classifications, with each galaxy in the sample classified three times. We also measure quantitative morphologies across all NIRCam filters. We find that galaxies at z 〉 3 have a wide diversity of morphologies. Galaxies with disks make up 60% of galaxies at z = 3, and this fraction drops to ∼30% at z = 6–9, while galaxies with spheroids make up ∼30%–40% across the redshift range, and pure spheroids with no evidence for disks or irregular features make up ∼20%. The fraction of galaxies with irregular features is roughly constant at all redshifts (∼40%–50%), while those that are purely irregular increases from ∼12% to ∼20% at z 〉 4.5. We note that these are apparent fractions, as many observational effects impact the visibility of morphological features at high redshift. On average, Spheroid-only galaxies have a higher Sérsic index, smaller size, and higher axis ratio than disk or irregular galaxies. Across all redshifts, smaller spheroid and disk galaxies tend to be rounder. Overall, these trends suggest that galaxies with established disks and spheroids exist across the full redshift range of this study, and further work with large samples at higher redshift is needed to quantify when these features first formed.
    Materialart: Online-Ressource
    ISSN: 2041-8205 , 2041-8213
    Sprache: Unbekannt
    Verlag: American Astronomical Society
    Publikationsdatum: 2023
    ZDB Id: 2207648-7
    ZDB Id: 2006858-X
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    In: The Astrophysical Journal, American Astronomical Society, Vol. 933, No. 2 ( 2022-07-01), p. 129-
    Kurzfassung: The 3D-Drift And SHift (3D-DASH) program is a Hubble Space Telescope (HST) WFC3 F160W imaging and G141 grism survey of the equatorial COSMOS field. 3D-DASH extends the legacy of HST near-infrared imaging and spectroscopy to degree-scale swaths of the sky, enabling the identification and study of distant galaxies ( z 〉 2) that are rare or in short-lived phases of galaxy evolution at rest-frame optical wavelengths. Furthermore, when combined with existing ACS/F814W imaging, the program facilitates spatially resolved studies of the stellar populations and dust content of intermediate redshift (0.5 〈 z 〈 2) galaxies. Here we present the reduced F160W imaging mosaic available to the community. Observed with the efficient DASH technique, the mosaic comprises 1256 individual WFC3 pointings, corresponding to an area of 1.35 deg 2 (1.43 deg 2 in 1912 when including archival data). The median 5 σ point-source limit in H 160 is 24.74 ± 0.20 mag. We also provide a point-spread function (PSF) generator tool to determine the PSF at any location within the 3D-DASH footprint. 3D-DASH is the widest HST/WFC3 imaging survey in the F160W filter to date, increasing the existing extragalactic survey area in the near-infrared at HST resolution by an order of magnitude.
    Materialart: Online-Ressource
    ISSN: 0004-637X , 1538-4357
    RVK:
    Sprache: Unbekannt
    Verlag: American Astronomical Society
    Publikationsdatum: 2022
    ZDB Id: 2207648-7
    ZDB Id: 1473835-1
    SSG: 16,12
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    In: The Astrophysical Journal Letters, American Astronomical Society, Vol. 943, No. 2 ( 2023-02-01), p. L9-
    Kurzfassung: Lyman-break galaxy (LBG) candidates at z ≳ 10 are rapidly being identified in James Webb Space Telescope (JWST)/NIRCam observations. Due to the (redshifted) break produced by neutral hydrogen absorption of rest-frame UV photons, these sources are expected to drop out in the bluer filters while being well detected in redder filters. However, here we show that dust-enshrouded star-forming galaxies at lower redshifts ( z ≲ 7) may also mimic the near-infrared (near-IR) colors of z 〉 10 LBGs, representing potential contaminants in LBG candidate samples. First, we analyze CEERS-DSFG-1, a NIRCam dropout undetected in the F115W and F150W filters but detected at longer wavelengths. Combining the JWST data with (sub)millimeter constraints, including deep NOEMA interferometric observations, we show that this source is a dusty star-forming galaxy (DSFG) at z ≈ 5.1. We also present a tentative 2.6 σ SCUBA-2 detection at 850 μ m around a recently identified z ≈ 16 LBG candidate in the same field and show that, if the emission is real and associated with this candidate, the available photometry is consistent with a z ∼ 5 dusty galaxy with strong nebular emission lines despite its blue near-IR colors. Further observations on this candidate are imperative to mitigate the low confidence of this tentative submillimeter emission and its positional uncertainty. Our analysis shows that robust (sub)millimeter detections of NIRCam dropout galaxies likely imply z ∼ 4–6 redshift solutions, where the observed near-IR break would be the result of a strong rest-frame optical Balmer break combined with high dust attenuation and strong nebular line emission, rather than the rest-frame UV Lyman break. This provides evidence that DSFGs may contaminate searches for ultra-high redshift LBG candidates from JWST observations.
    Materialart: Online-Ressource
    ISSN: 2041-8205 , 2041-8213
    Sprache: Unbekannt
    Verlag: American Astronomical Society
    Publikationsdatum: 2023
    ZDB Id: 2207648-7
    ZDB Id: 2006858-X
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    In: The Astrophysical Journal, American Astronomical Society, Vol. 952, No. 2 ( 2023-08-01), p. 133-
    Kurzfassung: The UltraViolet imaging of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey Fields (UVCANDELS) program provides Hubble Space Telescope (HST)/UVIS F275W imaging for four CANDELS fields. We combine this UV imaging with existing HST/near-IR grism spectroscopy from 3D-HST+AGHAST to directly compare the resolved rest-frame UV and H α emission for a sample of 979 galaxies at 0.7 〈 z 〈 1.5, spanning a range in stellar mass of 10 8−11.5 M ⊙ . Using a stacking analysis, we perform a resolved comparison between homogenized maps of rest-UV and H α to compute the average UV-to-H α luminosity ratio (an indicator of burstiness in star formation) as a function of galactocentric radius. We find that galaxies below stellar mass of ∼10 9.5 M ⊙ , at all radii, have a UV-to-H α ratio higher than the equilibrium value expected from constant star formation, indicating a significant contribution from bursty star formation. Even for galaxies with stellar mass ≳10 9.5 M ⊙ , the UV-to-H α ratio is elevated toward their outskirts ( R / R eff 〉 1.5), suggesting that bursty star formation is likely prevalent in the outskirts of even the most massive galaxies, but is likely overshadowed by their brighter cores. Furthermore, we present the UV-to-H α ratio as a function of galaxy surface brightness, a proxy for stellar mass surface density, and find that regions below ∼10 7.5 M ⊙ kpc −2 are consistent with bursty star formation, regardless of their galaxy stellar mass, potentially suggesting that local star formation is independent of global galaxy properties at the smallest scales. Last, we find galaxies at z 〉 1.1 to have bursty star formation, regardless of radius or surface brightness.
    Materialart: Online-Ressource
    ISSN: 0004-637X , 1538-4357
    RVK:
    Sprache: Unbekannt
    Verlag: American Astronomical Society
    Publikationsdatum: 2023
    ZDB Id: 2207648-7
    ZDB Id: 1473835-1
    SSG: 16,12
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 5
    In: Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP), Vol. 498, No. 1 ( 2020-10-11), p. 430-463
    Kurzfassung: Understanding the variability of galaxy star formation histories (SFHs) across a range of time-scales provides insight into the underlying physical processes that regulate star formation within galaxies. We compile the SFHs of galaxies at z = 0 from an extensive set of models, ranging from cosmological hydrodynamical simulations (Illustris, IllustrisTNG, Mufasa, Simba, EAGLE), zoom simulations (FIRE-2, g14, and Marvel/Justice League), semi-analytic models (Santa Cruz SAM) and empirical models (UniverseMachine), and quantify the variability of these SFHs on different time-scales using the power spectral density (PSD) formalism. We find that the PSDs are well described by broken power laws, and variability on long time-scales (≳1 Gyr) accounts for most of the power in galaxy SFHs. Most hydrodynamical models show increased variability on shorter time-scales (≲300 Myr) with decreasing stellar mass. Quenching can induce ∼0.4−1 dex of additional power on time-scales & gt;1 Gyr. The dark matter accretion histories of galaxies have remarkably self-similar PSDs and are coherent with the in situ star formation on time-scales & gt;3 Gyr. There is considerable diversity among the different models in their (i) power due to star formation rate variability at a given time-scale, (ii) amount of correlation with adjacent time-scales (PSD slope), (iii) evolution of median PSDs with stellar mass, and (iv) presence and locations of breaks in the PSDs. The PSD framework is a useful space to study the SFHs of galaxies since model predictions vary widely. Observational constraints in this space will help constrain the relative strengths of the physical processes responsible for this variability.
    Materialart: Online-Ressource
    ISSN: 0035-8711 , 1365-2966
    Sprache: Englisch
    Verlag: Oxford University Press (OUP)
    Publikationsdatum: 2020
    ZDB Id: 2016084-7
    SSG: 16,12
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
    In: The Astrophysical Journal Letters, American Astronomical Society, Vol. 940, No. 2 ( 2022-12-01), p. L55-
    Kurzfassung: We report the discovery of a candidate galaxy with a photo- z of z ∼ 12 in the first epoch of the James Webb Space Telescope (JWST) Cosmic Evolution Early Release Science Survey. Following conservative selection criteria, we identify a source with a robust z phot = 11.8 − 0.2 + 0.3 (1 σ uncertainty) with m F200W = 27.3 and ≳7 σ detections in five filters. The source is not detected at λ 〈 1.4 μ m in deep imaging from both Hubble Space Telescope (HST) and JWST and has faint ∼3 σ detections in JWST F150W and HST F160W, which signal a Ly α break near the red edge of both filters, implying z ∼ 12. This object (Maisie’s Galaxy) exhibits F115W − F200W 〉 1.9 mag (2 σ lower limit) with a blue continuum slope, resulting in 99.6% of the photo- z probability distribution function favoring z 〉 11. All data-quality images show no artifacts at the candidate’s position, and independent analyses consistently find a strong preference for z 〉 11. Its colors are inconsistent with Galactic stars, and it is resolved ( r h = 340 ± 14 pc). Maisie’s Galaxy has log M * / M ⊙ ∼ 8.5 and is highly star-forming (log sSFR ∼ −8.2 yr −1 ), with a blue rest-UV color ( β ∼ −2.5) indicating little dust, though not extremely low metallicity. While the presence of this source is in tension with most predictions, it agrees with empirical extrapolations assuming UV luminosity functions that smoothly decline with increasing redshift. Should follow-up spectroscopy validate this redshift, our universe was already aglow with galaxies less than 400 Myr after the Big Bang.
    Materialart: Online-Ressource
    ISSN: 2041-8205 , 2041-8213
    Sprache: Unbekannt
    Verlag: American Astronomical Society
    Publikationsdatum: 2022
    ZDB Id: 2207648-7
    ZDB Id: 2006858-X
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 7
    In: The Astrophysical Journal Letters, American Astronomical Society, Vol. 946, No. 1 ( 2023-03-01), p. L14-
    Kurzfassung: We report on the host properties of five X-ray-luminous active galactic nuclei (AGN) identified at 3 〈 z 〈 5 in the first epoch of imaging from the Cosmic Evolution Early Release Science Survey. Each galaxy has been imaged with the JWST Near-Infrared Camera, which provides rest-frame optical morphologies at these redshifts. We also derive stellar masses and star formation rates for each host by fitting its spectral energy distribution using a combination of galaxy and AGN templates. We find that three of the AGN hosts have spheroidal morphologies, one is a bulge-dominated disk, and one is dominated by pointlike emission. None are found to show strong morphological disturbances that might indicate a recent interaction or merger event. When compared to a sample of mass-matched inactive galaxies, we find that the AGN hosts have morphologies that are less disturbed and more bulge-dominated. Notably, all four of the resolved hosts have rest-frame optical colors consistent with a quenched or poststarburst stellar population. The presence of AGN in passively evolving galaxies at z 〉 3 is significant because a rapid feedback mechanism is required in most semianalytic models and cosmological simulations to explain the growing population of massive quiescent galaxies observed at these redshifts. Our findings show that AGN can continue to inject energy into these systems after their star formation is curtailed, potentially heating their halos and preventing renewed star formation. Additional observations will be needed to determine what role this feedback may play in helping to quench these systems and/or maintain their quiescent state.
    Materialart: Online-Ressource
    ISSN: 2041-8205 , 2041-8213
    Sprache: Unbekannt
    Verlag: American Astronomical Society
    Publikationsdatum: 2023
    ZDB Id: 2207648-7
    ZDB Id: 2006858-X
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 8
    In: The Astrophysical Journal Letters, American Astronomical Society, Vol. 937, No. 2 ( 2022-10-01), p. L35-
    Kurzfassung: Using data from JWST, we analyse the compact sources (“sparkles”) located around a remarkable z spec = 1.378 galaxy (the ‘Sparkler) that is strongly gravitationally lensed by the z = 0.39 galaxy cluster SMACS J0723.3-7327. Several of these compact sources can be cross-identified in multiple images, making it clear that they are associated with the host galaxy. Combining data from JWSTs Near-Infrared Camera (NIRCam) with archival data from the Hubble Space Telescope (HST), we perform 0.4–4.4 μ m photometry on these objects, finding several of them to be very red and consistent with the colors of quenched, old stellar systems. Morphological fits confirm that these red sources are spatially unresolved even in the strongly magnified JWST/NIRCam images, while the JWST/NIRISS spectra show [O iii ] λ 5007 emission in the body of the Sparkler but no indication of star formation in the red compact sparkles. The most natural interpretation of these compact red companions to the Sparkler is that they are evolved globular clusters seen at z = 1.378. Applying Dense Basis spectral energy distribution fitting to the sample, we infer formation redshifts of z form ∼ 7–11 for these globular cluster candidates, corresponding to ages of ∼3.9–4.1 Gyr at the epoch of observation and a formation time just ∼0.5 Gyr after the Big Bang. If confirmed with additional spectroscopy, these red, compact sparkles represent the first evolved globular clusters found at high redshift, which could be among the earliest observed objects to have quenched their star formation in the universe, and may open a new window into understanding globular cluster formation. Data and code to reproduce our results will be made available at http://canucs-jwst.com/sparkler.html .
    Materialart: Online-Ressource
    ISSN: 2041-8205 , 2041-8213
    Sprache: Unbekannt
    Verlag: American Astronomical Society
    Publikationsdatum: 2022
    ZDB Id: 2207648-7
    ZDB Id: 2006858-X
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 9
    In: The Astrophysical Journal, American Astronomical Society, Vol. 944, No. 2 ( 2023-02-01), p. 141-
    Kurzfassung: The study of galaxy evolution hinges on our ability to interpret multiwavelength galaxy observations in terms of their physical properties. To do this, we rely on spectral energy distribution (SED) models, which allow us to infer physical parameters from spectrophotometric data. In recent years, thanks to wide and deep multiwave band galaxy surveys, the volume of high-quality data have significantly increased. Alongside the increased data, algorithms performing SED fitting have improved, including better modeling prescriptions, newer templates, and more extensive sampling in wavelength space. We present a comprehensive analysis of different SED-fitting codes including their methods and output with the aim of measuring the uncertainties caused by the modeling assumptions. We apply 14 of the most commonly used SED-fitting codes on samples from the CANDELS photometric catalogs at z ∼ 1 and z ∼ 3. We find agreement on the stellar mass, while we observe some discrepancies in the star formation rate (SFR) and dust-attenuation results. To explore the differences and biases among the codes, we explore the impact of the various modeling assumptions as they are set in the codes (e.g., star formation histories, nebular, dust and active galactic nucleus models) on the derived stellar masses, SFRs, and A V values. We then assess the difference among the codes on the SFR–stellar mass relation and we measure the contribution to the uncertainties by the modeling choices (i.e., the modeling uncertainties) in stellar mass (∼0.1 dex), SFR (∼0.3 dex), and dust attenuation (∼0.3 mag). Finally, we present some resources summarizing best practices in SED fitting.
    Materialart: Online-Ressource
    ISSN: 0004-637X , 1538-4357
    RVK:
    Sprache: Unbekannt
    Verlag: American Astronomical Society
    Publikationsdatum: 2023
    ZDB Id: 2207648-7
    ZDB Id: 1473835-1
    SSG: 16,12
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 10
    In: The Astrophysical Journal Letters, American Astronomical Society, Vol. 949, No. 2 ( 2023-06-01), p. L25-
    Kurzfassung: We present JWST NIRSpec spectroscopy for 11 galaxy candidates with photometric redshifts of z ≃ 9 − 13 and M UV ∈ [ −21, −18] newly identified in NIRCam images in the Cosmic Evolution Early Release Science Survey. We confirm emission line redshifts for 7 galaxies at z = 7.762–8.998 using spectra at ∼1–5 μ m either with the NIRSpec prism or its three medium-resolution ( R ∼ 1000) gratings. For z ≃ 9 photometric candidates, we achieve a high confirmation rate of ≃90%, which validates the classical dropout selection from NIRCam photometry. No robust emission lines are identified in three galaxy candidates at z 〉 10, where the strong [O iii ] and H β lines would be redshifted beyond the wavelength range observed by NIRSpec, and the Ly α continuum break is not detected with the sensitivity of the current data. Compared with Hubble Space Telescope-selected bright galaxies ( M UV ≃ −22) that are similarly spectroscopically confirmed at z ≃ 8 − 9, these NIRCam-selected galaxies are characterized by lower star formation rates (SFRs; SFR ≃ 4 M ⊙ yr −1 ) and lower stellar masses (≃10 8 M ⊙ ), but with higher specific SFR (≃40 Gyr −1 ), higher [O iii ]+H β equivalent widths (≃1100 Å), and elevated production efficiency of ionizing photons ( log ( ξ ion / Hz erg − 1 ) ≃ 25.8 ) induced by young stellar populations ( 〈 10 Myr) accounting for ≃20% of the galaxy mass, highlighting the key contribution of faint galaxies to cosmic reionization. Taking advantage of the homogeneous selection and sensitivity, we also investigate metallicity and ISM conditions with empirical calibrations using the [O iii ] 5008 /H β ratio. We find that galaxies at z ≃ 8 − 9 have higher SFRs and lower metallicities than galaxies at similar stellar masses at z ≃ 2 − 6, which is generally consistent with the current galaxy formation and evolution models.
    Materialart: Online-Ressource
    ISSN: 2041-8205 , 2041-8213
    Sprache: Unbekannt
    Verlag: American Astronomical Society
    Publikationsdatum: 2023
    ZDB Id: 2207648-7
    ZDB Id: 2006858-X
    Standort Signatur Einschränkungen Verfügbarkeit
    BibTip Andere fanden auch interessant ...
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