A Value-added COSMOS2020 Catalog of Physical Properties: Constraining Temperature-dependent Initial Mass Function

Rusakov, Vadim; Steinhardt, Charles L.; Sneppen, Albert

doi:10.3847/1538-4365/acdde3

Cited by 4 publications

(1 citation statement)

References 113 publications

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“…Alternatively, the disparities among different studies could suggest the influence of additional physical parameters on the shape of the IMF, including the intensity of cosmic rays (Papadopoulos 2010;Fontanot et al 2018), gas temperature (Larson 1998;Rusakov et al 2023), and consequently, the redshift-dependent cosmic microwave background radiation (Bate 2023). For example, a redshift dependency of the IMF could lead to a deviation from the prediction of Model (ii) for galaxies with stable or increasing star formation activities (e.g., MW and SMC in Figure 4).…”

Section: Dependencies On Other Physical Parametersmentioning

confidence: 99%

The Variation in the Galaxy-wide Initial Mass Function for Low-mass Stars: Modeling and Observational Insights

Yan,

Li,

Kroupa

et al. 2024

ApJ

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The stellar initial mass function (IMF) characterizes the mass distribution of newly formed stars in various cosmic environments, serving as a fundamental assumption in astrophysical research. Recent findings challenge the prevalent notion of a universal and static IMF, proposing instead that the IMF’s shape is contingent upon the star formation environment. In this study, we analyze the galaxy-wide variation in the IMF for low-mass stars in both dwarf and massive galaxies with diverse observational methods. Despite systematic discrepancies between different approaches, an IMF model with a metallicity-dependent slope for the low-mass stars aligns with the majority of observations, indicating a high degree of uniformity in the star formation processes across the Universe. We also emphasize the need for a more comprehensive understanding of the variation in the low-mass IMF, considering measurement biases and factors beyond metallicity.

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Section: Dependencies On Other Physical Parametersmentioning

confidence: 99%

The Variation in the Galaxy-wide Initial Mass Function for Low-mass Stars: Modeling and Observational Insights

Yan,

Li,

Kroupa

et al. 2024

ApJ

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Outshining in the spatially resolved analysis of a strongly lensed galaxy at z = 6.072 with JWST NIRCam

Giménez-Arteaga,

Fujimoto,

Valentino

et al. 2024

A&A

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We present JWST/NIRCam observations of a strongly lensed, sub-$L^*$, multiply imaged galaxy at $z=6.072$, with magnification factors $ across the galaxy. The galaxy has rich HST, MUSE, and ALMA ancillary observations across a broad wavelength range. Aiming to quantify the reliability of stellar mass estimates of high redshift galaxies, we performed a spatially resolved analysis of the physical properties at scales of sim 200 pc, inferred from spectral energy distribution (SED) modelling of five JWST/NIRCam imaging bands covering 0.16 mu m $< rest <$ 0.63 mu m on a pixel-by-pixel basis. We find young stars surrounded by extended older stellar populations. By comparing and maps inferred from the image analysis with our additional NIRSpec integral field unit (IFU) data, we find that the spatial distribution and strength of the line maps are in agreement with the IFU measurements. We explore different parametric star formation history (SFH) forms with Bagpipes on the spatially integrated photometry, finding that a double power-law (DPL) star formation history retrieves the closest value to the spatially resolved stellar mass estimate, and other SFH forms suffer from the dominant outshining emission from the youngest stars, thus underestimating the stellar mass -- up to sim 0.5 dex--. On the other hand, the DPL cannot match the IFU-measured emission lines. Additionally, the ionising photon production efficiency may be overestimated in a spatially integrated approach by sim 0.15 dex, when compared to a spatially resolved analysis. The agreement with the IFU measurements implies that our pixel-by-pixel results derived from the broadband images are robust, and that the mass discrepancies we find with spatially integrated estimates are not just an effect of SED-fitting degeneracies or the lack of NIRCam coverage. Additionally, this agreement points towards the pixel-by-pixel approach as a way to mitigate the general degeneracy between the flux excess from emission lines and underlying continuum, especially when lacking photometric medium-band coverage and/or IFU observations. This study stresses the importance of studying galaxies as the complex systems that they are, resolving their stellar populations when possible, or using more flexible SFH parameterisations. This can aid our understanding of the early stages of galaxy evolution by addressing the challenge of inferring robust stellar masses and ionising photon production efficiencies of high redshift galaxies.

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Population synthesis of Be X-ray binaries: metallicity dependence of total X-ray outputs

Liu,

Sartorio,

Izzard

et al. 2023

Monthly Notices of the Royal Astronomical Society

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X-ray binaries (XRBs) are thought to regulate cosmic thermal and ionization histories during the Epoch of Reionization and Cosmic Dawn (z ∼ 5 − 30). Theoretical predictions of the X-ray emission from XRBs are important for modelling such early cosmic evolution. Nevertheless, the contribution from Be-XRBs, powered by accretion of compact objects from decretion disks around rapidly rotating O/B stars, has not been investigated systematically. Be-XRBs are the largest class of high-mass XRBs (HMXBs) identified in local observations and are expected to play even more important roles in metal-poor environments at high redshifts. In light of this, we build a physically motivated model for Be-XRBs based on recent hydrodynamic simulations and observations of decretion disks. Our model is able to reproduce the observed population of Be-XRBs in the Small Magellanic Cloud with appropriate initial conditions and binary stellar evolution parameters. We derive the X-ray output from Be-XRBs as a function of metallicity in the (absolute) metallicity range Z ∈ [10−4, 0.03] with a large suite of binary population synthesis (BPS) simulations. The simulated Be-XRBs can explain a non-negligible fraction ($\gtrsim 30{{\%}}$) of the total X-ray output from HMXBs observed in nearby galaxies for Z ∼ 0.0003 − 0.02. The X-ray luminosity per unit star formation rate from Be-XRBs in our fiducial model increases by a factor of ∼8 from Z = 0.02 to Z = 0.0003, which is similar to the trend seen in observations of all types of HMXBs. We conclude that Be-XRBs are potentially important X-ray sources that deserve greater attention in BPS of XRBs.

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A Value-added COSMOS2020 Catalog of Physical Properties: Constraining Temperature-dependent Initial Mass Function

Cited by 4 publications

References 113 publications

The Variation in the Galaxy-wide Initial Mass Function for Low-mass Stars: Modeling and Observational Insights

The Variation in the Galaxy-wide Initial Mass Function for Low-mass Stars: Modeling and Observational Insights

Outshining in the spatially resolved analysis of a strongly lensed galaxy at z = 6.072 with JWST NIRCam

Population synthesis of Be X-ray binaries: metallicity dependence of total X-ray outputs

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