arXiv subjects

Abdurro'uf

Publications and source records attributed to Abdurro'uf.

68 records · Page 4Linked to original sources

arXiv2023

JWST/NIRCam Probes Young Star Clusters in the Reionization Era Sunrise Arc

Star cluster formation in the early universe and their contribution to reionization remains to date largely unconstrained. Here we present JWST/NIRCam imaging of the most highly magnified galaxy known at z ~ 6, the Sunrise arc. We identify six young massive star clusters (YMCs) with measured radii spanning ~ 20 pc down to ~ 1 pc (corrected for lensing magnification), estimated stellar masses of ~ $10^{(6-7)}$ Msun, and with ages 1-30 Myr based on SED fitting to photometry measured in 8 filters extending to rest-frame 7000A. The resulting stellar mass surface densities are higher than 1000 Msun pc$^{-2}$ (up to a few $10^5$ Msun pc$^{-2}$) and their inferred dynamical ages qualify the majority of these systems as gravitationally-bound stellar clusters. The star cluster ages map the progression of star formation along the arc, with to evolved systems (>~ 10 Myr old) followed by very young clusters. The youngest stellar clusters (< 5 Myr) show evidence of prominent Hbeta + [OIII]4959,5007 emission, based on photometry, with equivalent widths larger than 1000 A rest-frame, and are hosted in a 200 pc sized star-forming complex. Such a region dominates the ionizing photon production, with a high efficiency log($ξ_{ion}$ [Hz erg$^{-1}$]) ~ 25.7. A significant fraction of the recently formed stellar mass of the galaxy (> 10-30 %) occurred in these YMCs. We speculate that such sources of ionizing radiation boost the ionizing photon production efficiency which eventually carve ionized channels that might favor the escape of Lyman continuum radiation. The survival of some of the clusters would make them the progenitors of massive and relatively metal-poor globular clusters in the local Universe.

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arXiv2023

Spatially Resolved Stellar Populations of $0.3<z<6.0$ Galaxies in WHL0137-08 and MACS0647+70 Clusters as Revealed by JWST: How do Galaxies Grow and Quench Over Cosmic Time?

We study the spatially resolved stellar populations of 444 galaxies at $0.3<z<6.0$ in two clusters (WHL0137-08 and MACS0647+70) and a blank field, combining imaging data from HST and JWST to perform spatially resolved spectral energy distribution (SED) modeling using pixedfit. The high spatial resolution of the imaging data combined with magnification from gravitational lensing in the cluster fields allows us to resolve some galaxies to sub-kpc scales (for 109 of our galaxies). At redshifts around cosmic noon and higher ($2.5\lesssim z\lesssim 6.0$), we find mass doubling times to be independent of radius, inferred from flat specific star formation rate (sSFR) radial profiles and similarities between the half-mass and half-SFR radii. At lower redshifts ($1.5\lesssim z\lesssim 2.5$), a significant fraction of our star-forming galaxies show evidence for nuclear starbursts, inferred from centrally elevated sSFR, and a much smaller half-SFR radius compared to the half-mass radius. At later epochs, we find more galaxies suppress star formation in their center but are still actively forming stars in the disk. Overall, these trends point toward a picture of inside-out galaxy growth consistent with theoretical models and simulations. We also observe a tight relationship between the central mass surface density and global stellar mass with $\sim 0.38$ dex scatter. Our analysis demonstrates the potential of spatially resolved SED analysis with JWST data. Future analysis with larger samples will be able to further explore the assembly of galaxy mass and the growth of their structures

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arXiv2022

JWST Imaging of Earendel, the Extremely Magnified Star at Redshift $z=6.2$

The gravitationally lensed star WHL0137-LS, nicknamed Earendel, was identified with a photometric redshift $z_{phot} = 6.2 \pm 0.1$ based on images taken with the Hubble Space Telescope. Here we present James Webb Space Telescope (JWST) Near Infrared Camera (NIRCam) images of Earendel in 8 filters spanning 0.8--5.0$μ$m. In these higher resolution images, Earendel remains a single unresolved point source on the lensing critical curve, increasing the lower limit on the lensing magnification to $μ> 4000$ and restricting the source plane radius further to $r < 0.02$ pc, or $\sim 4000$ AU. These new observations strengthen the conclusion that Earendel is best explained by an individual star or multiple star system, and support the previous photometric redshift estimate. Fitting grids of stellar spectra to our photometry yields a stellar temperature of $T_{\mathrm{eff}} \simeq 13000$--16000 K assuming the light is dominated by a single star. The delensed bolometric luminosity in this case ranges from $\log(L) = 5.8$--6.6 $L_{\odot}$, which is in the range where one expects luminous blue variable stars. Follow-up observations, including JWST NIRSpec scheduled for late 2022, are needed to further unravel the nature of this object, which presents a unique opportunity to study massive stars in the first billion years of the universe.

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arXiv2022

Compact dust emission in a gravitationally lensed massive quiescent galaxy at z = 2.15 revealed in ~130 pc-resolution observations by ALMA

We present new observations of MRG-M2129, a quiescent galaxy at z = 2.15 with the Atacama Large Millimeter/submillimeter Array (ALMA). With the combination of the gravitational lensing effect by the foreground cluster and the angular resolution provided by ALMA, our data reveal 1.2 mm continuum emission at $\sim130$ pc angular resolution. Compact dust continuum is detected at 7.9 $σ$ in the target but displaced from its stellar peak position by $62 \pm 38$ mas, or $\sim169 \pm 105$ pc in the source plane. We find considerably high dust-to-stellar mass ratio, $4 \times 10^{-4}$. From non-detection of the [C i] 3P2 -> 3P1 line, we then derive $3 σ$ upper limits on the molecular gas-to-dust mass ratio $δ_\mathrm{GDR} < 60$ and the molecular gas-to-stellar mass ratio fH2 < 2.3%. The derived $δ_\mathrm{GDR}$ is $>2\times$ smaller than the typical value assumed for quiescent galaxies in the literature. Our study supports that there exists a broad range of $δ_\mathrm{GDR}$ and urges submillimeter follow-up observations of quenching/recently quenched galaxies at similar redshifts. Based on the derived low $δ_\mathrm{GDR}$ and other observed dust properties, we argue that the central black hole is still active and regulates star formation in the system. Our study exhibits a rare case of a gravitationally lensed type 2 QSO harbored by a quiescent galaxy.

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arXiv2022

A Multiwavelength view of IC 860: What Is in Action inside Quenching Galaxies

We present a multiwavelength study of IC 860, a nearby post-starburst galaxy at the early stage of transitioning from blue and star-forming to red and quiescent. Optical images reveal a galaxy-wide, dusty outflow originating from a compact core. We find evidence for a multiphase outflow in the molecular and neutral gas phase from the CO position-velocity diagram and NaD absorption features. We constrain the neutral mass outflow rate to be ~0.5 M$_{\odot}/$yr, and the total hydrogen mass outflow rate to be ~12 M$_{\odot}$/yr. Neither outflow component seems able to escape the galaxy. We also find evidence for a recent merger in the optical images, CO spatial distribution, and kinematics, and evidence for a buried AGN in the optical emission line ratios, mid-IR properties, and radio spectral shape. The depletion time of the molecular gas reservoir under the current star formation rate is ~7 Gyr, indicating that the galaxy could stay at the intermediate stage between the blue and red sequence for a long time. Thus the timescales for a significant decline in star formation rate ("quenching") and gas depletion are not necessarily the same. Our analysis supports the quenching picture where outflows help suppress star formation by disturbing rather than expelling the gas and shed light on possible ongoing activities in similar quenching galaxies.

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arXiv2022

Dissecting Nearby Galaxies with piXedfit: II. Spatially Resolved Scaling Relations Among Stars, Dust, and Gas

We study spatially resolved scaling relations among stars, dust, and gas in ten nearby spiral galaxies. In a preceding paper Abdurro'uf et al. (2022), we have derived spatially resolved properties of the stellar population and dust by panchromatic spectral energy distribution (SED) fitting using piXedfit. Now, we investigate resolved star formation ($Σ_{\rm H_{2}}$--$Σ_{\rm SFR}$--$Σ_{*}$) and dust scaling relations. While the relations with all sub-galactic regions of the galaxies are reasonably tight ($σ\lesssim 0.3$ dex), we find that most of the scaling relations exhibit galaxy-to-galaxy variations in normalization and shape. Only two relations of $Σ_{\rm dust}$--$Σ_{\rm gas}$ and $Σ_{\rm dust}$--$Σ_{\rm H_{2}}$ do not show noticeable galaxy-to-galaxy variations among our sample galaxies. We further investigate correlations among the scaling relations. We find significant correlations among the normalization of the $Σ_{\rm H_{2}}$--$Σ_{\rm SFR}$--$Σ_{*}$ relations, which suggest that galaxies with higher levels of resolved $\text{H}_{2}$ fraction ($f_{\rm H_{2}}$) tend to have higher levels of resolved star formation efficiency (SFE) and specific star formation rate (sSFR). We also observe that galaxies with higher levels of resolved dust-to-stellar mass ratios tend to have higher levels of resolved sSFR, SFE, and $f_{\rm H_{2}}$. Moreover, we find that galaxies with higher global sSFR and less compact morphology tend to have higher levels of the resolved sSFR, SFE, and $f_{\rm H_{2}}$, which can explain the variations in the normalization of the $Σ_{\rm H_{2}}$--$Σ_{\rm SFR}$--$Σ_{*}$ relationships. Overall, we observe indications of the contributions of both global and local factors in governing the star formation process in galaxies.

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arXiv2022

The Seventeenth Data Release of the Sloan Digital Sky Surveys: Complete Release of MaNGA, MaStar and APOGEE-2 Data

This paper documents the seventeenth data release (DR17) from the Sloan Digital Sky Surveys; the fifth and final release from the fourth phase (SDSS-IV). DR17 contains the complete release of the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, which reached its goal of surveying over 10,000 nearby galaxies. The complete release of the MaNGA Stellar Library (MaStar) accompanies this data, providing observations of almost 30,000 stars through the MaNGA instrument during bright time. DR17 also contains the complete release of the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) survey which publicly releases infra-red spectra of over 650,000 stars. The main sample from the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), as well as the sub-survey Time Domain Spectroscopic Survey (TDSS) data were fully released in DR16. New single-fiber optical spectroscopy released in DR17 is from the SPectroscipic IDentification of ERosita Survey (SPIDERS) sub-survey and the eBOSS-RM program. Along with the primary data sets, DR17 includes 25 new or updated Value Added Catalogs (VACs). This paper concludes the release of SDSS-IV survey data. SDSS continues into its fifth phase with observations already underway for the Milky Way Mapper (MWM), Local Volume Mapper (LVM) and Black Hole Mapper (BHM) surveys.

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arXiv2021

Dissecting Nearby Galaxies with piXedfit: I. Spatially Resolved Properties of Stars, Dust, and Gas as Revealed by Panchromatic SED Fitting

We study spatially resolved properties (on spatial scales of $\sim 1-2$ kpc out to at least $3$ effective radii) of the stars, dust, and gas in ten nearby spiral galaxies. The properties of the stellar population and dust are derived by fitting the spatially resolved spectral energy distribution (SED) with more than 20 photometric bands ranging from far-ultraviolet to far-infrared. Our newly developed software piXedfit performs point spread function matching of images, pixel binning, and models the stellar light, dust attenuation, dust emission, and emission from a dusty torus heated by an active galactic nucleus simultaneously through the energy balance approach. With this self-consistent analysis, we present the spatially resolved version of the IRX--$β$ relation, finding that it is consistent with the relationship from the integrated photometry. We show that the old stellar populations contribute to the dust heating, which causes an overestimation of star formation rate (SFR) derived from the total ultraviolet and infrared luminosities on kpc scales. With archival high-resolution maps of atomic and molecular gas, we study the radial variation of the properties of the stellar populations (including stellar mass, age, metallicity, and SFR), dust (including dust mass, dust temperature, and abundance of polycyclic aromatic hydrocarbon), gas, as well as dust-to-stellar mass and dust-to-gas mass ratios. We observe a depletion of molecular gas mass fraction in the central region of the majority of the galaxies, suggesting that the lack of available fuel is an important factor in suppressing the specific SFR at the center.

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arXiv2021

Introducing piXedfit -- a Spectral Energy Distribution Fitting Code Designed for Resolved Sources

We present piXedfit, pixelized spectral energy distribution (SED) fitting, a Python package that provides tools for analyzing spatially resolved properties of galaxies using multiband imaging data alone or in combination with integral field spectroscopy (IFS) data. piXedfit has six modules that can handle all tasks in the spatially resolved SED fitting. The SED fitting module uses the Bayesian inference technique with two kinds of posteriors sampling methods: Markov Chain Monte Carlo (MCMC) and random densely-sampling of parameter space (RDSPS). We test the performance of the SED fitting module using mock SEDs of simulated galaxies from IllustrisTNG. The SED fitting with both posteriors sampling methods can recover physical properties and star formation histories of the IllustrisTNG galaxies well. We further test the performance of piXedfit modules by analyzing 20 galaxies observed by the CALIFA and MaNGA surveys. The data comprises of 12-band imaging data from GALEX, SDSS, 2MASS, and WISE, and the IFS data from CALIFA or MaNGA. piXedfit can spatially match (in resolution and sampling) of the imaging and IFS data. By fitting only the photometric SEDs, piXedfit can predict the spectral continuum, $\text{D}_{\rm n}4000$, $H_α$, and $H_β$ well. The star formation rate (SFR) derived by piXedfit is consistent with that derived from $H_α$ emission. The RDSPS method gives equally good fitting results as the MCMC and it is much faster than the MCMC. piXedfit is a versatile tool equipped with a parallel computing module for efficient analysis of large datasets, and will be made publicly available (https://github.com/aabdurrouf/piXedfit).

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arXiv2021

Extremely Low Molecular Gas Content in the Vicinity of a Red Nugget Galaxy at $z=1.91$

We present Atacama Large Millimeter/submillimeter Array (ALMA) Band 5 observations of a galaxy at $z=1.91$, GDS24569, in search of molecular gas in its vicinity via the [C I] $^3$P$_1$-$^3$P$_0$ line. GDS24569 is a massive ($\log M_*/M_\odot=11$) passively evolving galaxy, and characterized by compact morphology with an effective radius of $\sim0.5$ kpc. We apply two blind detection algorithms to the spectral data cubes, and find no promising detection in or around GDS24569 out to projected distance of $\sim320$ kpc, while a narrow tentative line ($4.1 σ$) is identified at $+1200$ km/s by one of the algorithms. From the non-detection of [C I], we place a $3σ$ upper limit on molecular hydrogen mass, $\sim 7.1 \times 10^9 M_\odot$, which converts to an extremely low gas-to-stellar mass fraction, $< 5 \%$. We conduct a spectral energy distribution modeling by including optical-to-far-infrared data, and find a considerably high ($\sim0.1\%$) dust-to-stellar mass ratio, $\sim10$-$100\times$ higher than those of local early-type galaxies. In combination with a previous result of an insufficient number of surrounding satellite galaxies, it is suggested that GDS24569 is unlikely to experience significant size evolution via satellite mergers. We discuss possible physical mechanisms that quenched GDS24569.

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arXiv2020

Tracing the co-evolution path of super massive black holes and spheroids with AKARI-selected ultra-luminous IR galaxies at intermediate redshifts

We present the stellar population and ionized-gas outflow properties of ultra-luminous IR galaxies (ULIRGs) at $z=$ 0.1-1.0, which are selected from AKARI FIR all-sky survey. We construct a catalog of 1077 ULIRGs to examine feedback effect after major mergers. 202 out of the 1077 ULIRGs are spectroscopically identified by SDSS and Subaru/FOCAS observations. Thanks to deeper depth and higher resolution of AKARI compared to the previous IRAS survey, and reliable identification from WISE MIR pointing, the sample is unique in identifying optically-faint (i$\sim$20) IR-bright galaxies, which could be missed in previous surveys. A self-consistent spectrum-SED decomposition method, which constrains stellar population properties in SED modeling based on spectral fitting results, has been employed for 149 ULIRGs whose optical continua are dominated by host galaxies. They are massive galaxies ($M_{\rm star}\sim10^{11}$-$10^{12}$ M$_{\odot}$), associated with intense star formation activities (SFR $\sim$ 200-2000 M$_{\odot}$ yr$^{-1}$). The sample covers a range of AGN bolometric luminosity of $10^{10}$-$10^{13}$ L$_{\odot}$, and the outflow velocity measured from [OIII] 5007A line shows a correlation with AGN luminosity. Eight galaxies show extremely fast outflows with velocity up to 1500-2000 km s$^{-1}$. However, the co-existence of vigorous starbursts and strong outflows suggests the star formation has not been quenched during the ULIRG phase. By deriving stellar mass and mass fraction of young stellar population, we find no significant discrepancies between stellar properties of ULIRGs with weak and powerful AGNs. The results are not consistent with the merger-induced evolutionary scenario, which predicts that SF-dominated ULIRGs show smaller stellar mass and younger stellar populations compared to AGN-dominated ULIRGs.

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arXiv2019

Spatially resolved stellar mass buildup and quenching in massive disk galaxies over the last 10 Gyr revealed with spatially resolved SED fitting

Despite decreasing cosmic star formation rate density over the last 10 Gyr, the stellar mass ($M_{*}$) buildups in galaxies were still progressing during this epoch. About 50\% of the current $M_{*}$ density in the universe was built over the last $\sim 8.7$ Gyr. In this research, we investigated the stellar mass buildup and quenching of spatially resolved regions within massive disk galaxies over the last 10 Gyr. We apply the spectral energy distribution (SED) fitting method to SEDs of sub-galactic regions in galaxies to derive the spatially resolved distributions of SFR and $M_{*}$ in the galaxies. This namely \textit{pixel-to-pixel SED fitting} method is applied to massive disk galaxies at $0.01<z<0.02$ and $0.8<z<1.8$. We found that massive disk galaxies tend to build their $M_{*}$ and quench their star formation progressively from the central region to the outskirts, i.e. \textit{inside-out} stellar mass buildup and quenching.

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arXiv2018

Evolution of spatially resolved star formation main sequence and surface density profiles in massive disc galaxies at $0\lesssim z \lesssim 1$: inside-out stellar mass buildup and quenching

We investigate a relation between surface densities of star formation rate (SFR) and stellar mass ($M_{*}$) at a $\sim 1$ kpc scale namely spatially resolved star formation main sequence (SFMS) in massive ($\log(M_{*}/M_{\odot})>10.5$) face-on disc galaxies at $0.01<z<0.02$ and $0.8<z<1.8$ and examine evolution of the relation. The spatially resolved SFMS of $z\sim 0$ galaxies is discussed in a companion paper. For $z\sim 1$ sample, we use 8 bands imaging dataset from CANDELS and 3D-HST and perform a pixel-to-pixel SED fitting to derive the spatially resolved SFR and $M_{*}$. We find a linear spatially resolved SFMS in the $z\sim 1$ galaxies that lie on the global SFMS, while a 'flattening' at high $Σ_{*}$ end is found in that relation for the galaxies that lie below the global SFMS. Comparison with the spatially resolved SFMS of the $z\sim 0$ galaxies shows smaller difference in the specific SFR (sSFR) at low $Σ_{*}$ than that at high $Σ_{*}$. This trend is consistent with the evolution of the sSFR$(r)$ radial profile, which shows a faster decrease in the central region than in the outskirt, agrees with the inside-out quenching scenario. We then derive an empirical model for the evolution of the $Σ_{*}(r)$, $Σ_{\rm SFR}(r)$ and sSFR$(r)$ radial profiles. Based on the empirical model, we estimate the radial profile of the quenching timescale and reproduce the observed spatially resolved SFMS at $z\sim 1$ and $z\sim 0$.

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arXiv2017

Understanding the Scatter in the Spatially-resolved Star Formation Main Sequence of Local Massive Spiral Galaxies

We investigate the relation between star formation rate (SFR) and stellar mass ($M_*$) in sub-galactic ($\sim 1$kpc) scale of 93 local ($0.01 10^{10.5}M_{\odot}$) spiral galaxies. To derive spatially-resolved SFR and stellar mass, we perform so-called pixel-to-pixel SED fitting, which fits an observed spatially-resolved multiband SED with a library of model SEDs using Bayesian statistics approach. We use 2 bands (FUV and NUV) and 5 bands ($u$, $g$, $r$, $i$, and $z$) imaging data from Galaxy Evolution Explorer (GALEX) and Sloan Digital Sky Survey (SDSS), respectively. We find a tight nearly linear relation between the local surface density of SFR ($Σ_{\rm{SFR}}$) and stellar mass ($Σ_{*}$) which has flattening in high $Σ_{*}$. The near linear relation between $Σ_{*}$ and $Σ_{\rm SFR}$ suggests constant sSFR throughout the galaxies, and the scatter of the relation is directly related to that of sSFR. Therefore, we analyse the variation of sSFR in various scales. More massive galaxies on average have lower sSFR throughout them than less massive galaxies. We also find that barred galaxies have lower sSFR in a core region than non-barred galaxies. However, in the outside region, sSFR of barred and non-barred galaxies are similar and lead to the similar total sSFR.

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