The physical processes that establish the morphological evolution and the structural diversity of galaxies are key unknowns in extragalactic astrophysics. Here we report the finding of the morphologically-mature galaxy JADES-GS+53.18343-27.79097, which existed within the first 700 million years of the Universe's history. This star-forming galaxy with a stellar mass of $10^{8.6}$ solar masses consists of three components, a highly-compact core with a half-light radius of 144 pc, a strongly star-forming disc with a radius of 468 pc, and a star-forming clump, which all show distinctive star-formation histories. The central stellar mass density of this galaxy is within a factor of two of the most massive present-day ellipticals, while being globally 1000 times less massive. The radial profile of the specific star-formation rate is strongly rising toward the outskirts. This evidence strongly suggests the first detection of inside-out growth of a galaxy as a proto-bulge and a star-forming disc in the Epoch of Reionization.

Stellar mass

Solar mass

Star (game theory)

Billion years

10.48550/arxiv.2306.02472

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Citations (4)

The Small-scale Clustering of Luminous Red Galaxies via Cross-Correlation Techniques

arXiv (Cornell University) (2004)

Daniel J. Eisenstein Michael R. Blanton Idit Zehavi Neta A. Bahcall J. Brinkmann

We present the small-scale (0.2h^{-1} to 7h^{-1} Mpc) cross-correlations between 32,000 luminous early-type galaxies and a reference sample of 16 million normal galaxies from the Sloan Digital Sky Survey. Our method allows us to construct the spherically averaged, real-space cross-correlation function between the spectroscopic LRG sample and galaxies from the SDSS imaging. We report the cross-correlation as a function of scale, luminosity, and redshift. We find very strong luminosity dependences in the clustering amplitudes, up to a factor of 4 over a factor of 4 in luminosity, and measure this dependence with high signal-to-noise ratio. The luminosity dependence of bias is found to depend on scale, with more variation on smaller scales. The clustering as a function of scale is not a power law, but instead has a dip at 1h^{-1} Mpc and an excess on small scales. The fraction of red galaxies within the L* sample surrounding LRGs is a strong function of scale, as expected. However, the fraction of red galaxies evolves in redshift similarly on small and large scales, suggesting that cluster and field populations are changing in the same manner. The results highlight the advantage on small scales of using cross-correlation methods as a means of avoiding shot noise in samples of rare galaxies.

10.48550/arxiv.astro-ph/0411559

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JWST NIRCam+NIRSpec: Interstellar medium and stellar populations of young galaxies with rising star formation and evolving gas reservoirs

arXiv (Cornell University) (2022)

Sandro Tacchella Benjamin D. Johnson Brant Robertson Stefano Carniani Francesco D’Eugenio

We present an interstellar medium and stellar population analysis of three spectroscopically confirmed $z>7$ galaxies in the ERO JWST NIRCam and JWST NIRSpec data of the SMACS J0723.3-7327 cluster. We use the Bayesian spectral energy distribution (SED) fitting code \texttt{Prospector} with a flexible star-formation history (SFH), a variable dust attenuation law, and a self-consistent model of nebular emission (continuum and emission lines). Importantly, we self-consistently fit both the emission line fluxes from JWST NIRSpec and the broad-band photometry from JWST NIRCam, taking into account slit-loss effects. We find that these three $z=7.6-8.5$ galaxies ($M_{\star}\approx10^{8}~M_{\odot}$) are young with rising SFHs and mass-weighted ages of $3-4$ Myr, though we find indications for underlying older stellar populations. The inferred gas-phase metallicities broadly agree with the direct metallicity estimates from the auroral lines. The galaxy with the lowest gas-phase metallicity ($\mathrm{Z}_{\rm gas}=0.06~\mathrm{Z}_{\odot}$) has a steeply rising SFH, is very compact ($<0.2~\mathrm{kpc}$) and has a high star-formation rate surface density ($Σ_{\rm SFR}\approx22~\mathrm{M}_{\odot}~\mathrm{yr}^{-1}~\mathrm{kpc}^{-2}$), consistent with rapid gas accretion. The two other objects with higher gas-phase metallicity show more complex multi-component morphologies on kpc scales, indicating that their recent increase in star-formation rate is driven by mergers or internal, gravitational instabilities. We discuss effects of assuming different SFH priors or only fitting the photometric data. Our analysis highlights the strength and importance of combining JWST imaging and spectroscopy for fully assessing the nature of galaxies at the earliest epochs.

Stellar population

10.48550/arxiv.2208.03281

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Citations (7)

Astro2020 science white paper inflation and dark energy from spectroscopy at z > 2

Simone Ferraro Michael Wilson Muntazir Abidi David Alonso Behzad Ansarinejad

White (mutation)

Source

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Citations (0)

Low‐Resolution Spectral Templates for Galaxies from 0.2 to 10 μm

The Astrophysical Journal (2008)

Roberto J. Assef C. S. Kochanek M. Brodwin M. J. I. Brown Nelson Caldwell

We built an optimal basis of low resolution templates for galaxies over the wavelength range from 0.2 to 10 $μ$m using a variant of the algorithm presented by Budavari et al. (2000). We derived them using eleven bands of photometry from the NDWFS, FLAMEX, zBoötes and IRAC Shallow surveys for 16033 galaxies in the NDWFS Boötes field with spectroscopic redshifts measured by the AGN and Galaxy Evolution Survey. We also developed algorithms to accurately determine photometric redshifts, K corrections and bolometric luminosities using these templates. Our photometric redshifts have an accuracy of $σ_z/(1+z) = 0.04$ when clipped to the best 95%. We used these templates to study the spectral type distribution in the field and to estimate luminosity functions of galaxies as a function of redshift and spectral type. In particular, we note that the 5-8$μ$m color distribution of galaxies is bimodal, much like the optical g--r colors.

Photometric redshift

10.1086/527533

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Citations (64)

Constraints on the Cosmic Near‐Infrared Background Excess from NICMOS Deep Field Observations

The Astrophysical Journal (2007)

Rodger I. Thompson Daniel J. Eisenstein Xiaohui Fan Marcia Rieke Robert C. Kennicutt

NICMOS observations of the resolved object fluxes in the Hubble Deep Field North and the Hubble Ultra Deep Field are significantly below the fluxes attributed to a 1.4 - 1.8 microns Near InfraRed Background Excess (NIRBE) from previous low spatial resolution NIRS measurements. Tests placing sources in the NICMOS image with fluxes sufficient to account for the NIRBE indicate that the NIRBE flux must be either flat on scales greater than 100 arc second or clumped on scales of several arc minutes to avoid detection in the NICMOS image. A fluctuation analysis of the new NICMOS data shows a fluctuation spectrum consistent with that found at the same wavelength in deep 2MASS calibration images. The fluctuation analysis shows that the majority of the fluctuation power comes from resolved galaxies at redshifts of 1.5 and less and that the fluctuations observed in the earlier deep 2MASS observations can be completely accounted for with normal low redshift galaxies. Neither the NICMOS direct flux measurements nor the fluctuation analysis require an additional component of near infrared flux other than the flux from normal resolved galaxies in the redshift range between 0 and 7. The residual fluctuations in the angular range between 1 and 10 arc seconds is 1-2 nW m-2 sr-1 which is at or above several predictions of fluctuations from high redshift population III objects, but inconsistent with attributing the entire NIRBE to high redshift galaxies.

Hubble Ultra-Deep Field

Cosmic infrared background

Photometric redshift

10.1086/511380

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Citations (59)

A Helium White Dwarf of Extremely Low Mass

The Astrophysical Journal (2004)

James Liebert P. Bergeron Daniel J. Eisenstein Hugh C. Harris S. J. Kleinman

We analyze the spectrum of an unusually low mass white dwarf, SDSS J123410.37-022802.9 (0335-264-52000), found in our recent, white dwarf catalog from the first data release (DR1) of the Sloan Digital Sky Survey (SDSS). Two independent, model atmosphere fits result in an accurate determination of atmospheric and stellar parameters. The more hands-on analysis yields Teff = 17,470 ± 750 K and log g = 6.38 ± 0.05. We argue that the object cannot be a main-sequence A star, a horizontal-branch star, or a subdwarf B star. Instead, it is interpreted as a very low mass white dwarf with a core composed of helium, with mass ~0.18-0.19 M☉, similar to that published previously for the unusual companion to the millisecond pulsar J1012+5307. The star probably remains in a binary, perhaps even with an undiscovered or dead pulsar companion. However, the companion might be a more ordinary star, provided Roche lobe mass transfer began shortly after the now-visible component left the main sequence. A second SDSS low-mass white dwarf candidate is also analyzed, but the spectrum for this fainter object is of poorer quality. The sample appears to include additional, similar candidates, worthy of more accurate observation. Correct identification of any additional white dwarfs of extremely low mass requires careful observation and interpretation.

Subdwarf

Low Mass

Black dwarf

Effective temperature

10.1086/421462

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Citations (51)

Spectroscopic confirmation of two luminous galaxies at a redshift of 14

Nature (2024)

Stefano Carniani Kevin Hainline Francesco D’Eugenio Daniel J. Eisenstein P. Jakobsen

10.1038/s41586-024-07860-9

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Citations (25)

Minor merger growth in action: JWST detects faint blue companions around massive quiescent galaxies at 0.5 < z < 3

arXiv (Cornell University) (2023)

Katherine A. Suess Christina C. Williams Brant Robertson Zhiyuan Ji Benjamin D. Johnson

Minor mergers are thought to drive the structural evolution of massive quiescent galaxies; however, existing HST imaging is primarily sensitive to stellar mass ratios >1:10. Here, we report the discovery of a large population of low-mass companions within 35 kpc of known logM*/Msun > 10.5 quiescent galaxies at 0.5 < z < 3. While massive companions like those identified by HST are rare, JWST imaging from JADES reveals that the average massive quiescent galaxy hosts ~5 nearby companions with stellar mass ratios <1:10. Despite a median stellar mass ratio of just 1:900, these tiny companions are so numerous that they represent at least 30\% of the total mass being added to quiescent galaxies via minor mergers. While relatively massive companions have colors similar to their hosts, companions with mass ratios <1:10 typically have bluer colors and lower mass-to-light ratios than their host galaxies at similar radii. The accretion of these tiny companions is likely to drive evolution in the color gradients and stellar population properties of the host galaxies. Our results suggest that the well-established ``minor merger growth" model for quiescent galaxies extends down to very low mass ratios of <1:100, and demonstrates the power of JWST to constrain both the spatially-resolved properties of massive galaxies and the properties of low-mass companions beyond the local universe.

Stellar mass

Low Mass

10.48550/arxiv.2307.14209

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Galaxies at [FORMULA][F]z~7-8[/F][/FORMULA]: [FORMULA][F]z[INF]850[/INF][/F][/FORMULA]-Dropouts in the Hubble Ultra Deep Field

The Astrophysical Journal (2004)

R. J. Bouwens Rodger I. Thompson G. D. Illingworth Marijn Franx Pieter van Dokkum

We have detected likely z ~ 7-8 galaxies in the 144'' × 144'' Near-Infrared Camera and Multi-Object Spectrometer (NICMOS) observations of the Hubble Ultra Deep Field. Objects are required to be ≥3 σ detections in both NICMOS bands, J110 and H160. The selection criteria for this sample are (z850 - J110)AB > 0.8, (z850 - J110)AB > 0.66(J110 - H160)AB + 0.8, (J110 - H160)AB < 1.2 and no detection at less than 8500 Å. The five selected sources have total magnitudes H160, AB ~ 27. Four of the five sources are quite blue compared to typical lower redshift dropout galaxies and are clustered within a 1 arcmin2 region. Because all five sources are near the limit of the NICMOS data, we have carefully evaluated their reality. Each of the candidates is visible in different splits of the data and a median stack. We analyzed several noise images and estimate the number of spurious sources to be 1 ± 1. A search using an independent reduction of this same data set clearly revealed three of the five candidates and weakly detected a fourth candidate, suggesting that the contamination could be higher. For comparison with predictions from lower redshift samples, we take a conservative approach and adopt four z ~ 7-8 galaxies as our sample. With the same detection criteria on simulated data sets, assuming no evolution from z ~ 3.8, we predict 10 sources at z ~ 7-8, or 14 if we use a more realistic (1 + z)-1 size scaling. We estimate that the rest-frame continuum UV (~1800 Å) luminosity density at z ~ 7.5 (integrated down to 0.3L) is just 0.20 times that found at z ~ 3.8 (or 0.20 times this quantity including cosmic variance). Effectively this sets an upper limit on the luminosity density down to 0.3L and is consistent with significant evolution at the bright end of the luminosity function from z ~ 7.5 to 3.8. Even with the lower UV luminosity density at z ~ 7.5, it appears that galaxies could still play an important role in reionization at these redshifts, although definitive measurements remain to be made.

Hubble Ultra-Deep Field

Spurious relationship

Data Reduction

10.1086/426503

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Citations (161)