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Register a new userLyman-$alpha$ emission from a WISE-selected optically faint powerful radio galaxy M151304.72-252439.7 at $z$ = 3.132
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We report the detection of a large ($sim90$ kpc) and luminous $mathrm{Lyalpha}$ nebula [$Lmathrm{_{Lyalpha}}$ = $(6.80pm0.08)times 10^{44}$] $rm{,erg,s^{-1}}$ around an optically faint (r$>23$ mag) radio galaxy M1513-2524 at $zmathrm{_{em}}$=3.132. The double-lobed radio emission has an extent of 184 kpc, but the radio core, i.e., emission associated with the active galactic nucleus (AGN) itself, is barely detected. This object was found as part of our survey to identify high-$z$ quasars based on Wide-field Infrared Survey Explorer (WISE) colors. The optical spectrum has revealed $mathrm{Lyalpha}$, NV, CIV and HeII emission lines with a very weak continuum. Based on long-slit spectroscopy and narrow band imaging centered on the $mathrm{Lyalpha}$ emission, we identify two spatial components: a compact component with high velocity dispersion ($sim 1500$$rm{,km,s^{-1}}$) seen in all three lines, and an extended component, having low velocity dispersion (i.e., 700-1000$rm{,km,s^{-1}}$). The emission line ratios are consistent with the compact component being in photoionization equilibrium with an AGN. We also detect spatially extended associated $mathrm{Lyalpha}$ absorption, which is blue-shifted within 250-400$rm{,km,s^{-1}}$ of the $mathrm{Lyalpha}$ peak. The probability of $mathrm{Lyalpha}$ absorption detection in such large radio sources is found to be low ($sim$10%) in the literature. M1513-2524 belongs to the top few percent of the population in terms of $mathrm{Lyalpha}$ and radio luminosities. Deep integral field spectroscopy is essential for probing this interesting source and its surroundings in more detail.
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Galaxies at high redshifts provide a valuable tool to study cosmic dawn, and therefore it is crucial to reliably identify these galaxies. Here, we present an unambiguous and first simultaneous detection of both the Lyman-alpha emission and the Lyman break from a z = 7.512+/- 0.004 galaxy, observed in the Faint Infrared Grism Survey (FIGS). These spectra, taken with G102 grism on Hubble Space Telescope (HST), show a significant emission line detection (6 sigma) in multiple observational position angles (PA), with total integrated Ly{alpha} line flux of 1.06+/- 0.12 e10-17erg s-1cm-2. The line flux is nearly a factor of four higher than the previous MOSFIRE spectroscopic observations of faint Ly{alpha} emission at {lambda} = 1.0347{mu}m, yielding z = 7.5078+/- 0.0004. This is consistent with other recent observations implying that ground-based near-infrared spectroscopy underestimates total emission line fluxes, and if confirmed, can have strong implications for reionization studies that are based on ground-based Lyman-{alpha} measurements. A 4-{sigma} detection of the NV line in one PA also suggests a weak Active Galactic Nucleus (AGN), potentially making this source the highest-redshift AGN yet found. Thus, this observation from the Hubble Space Telescope clearly demonstrates the sensitivity of the FIGS survey, and the capability of grism spectroscopy to study the epoch of reionization.
I report a tentative ($sim4sigma$) emission line at $ u=100.84,$GHz from COS-3mm-1, a 3mm-selected galaxy reported by Williams et al. 2019 that is undetected at optical and near infrared wavelengths. The line was found in the ALMA Science Archive after re-processing ALMA band 3 observations targeting a different source. Assuming the line corresponds to the $rm CO(6to5)$ transition, this tentative detection implies a spectroscopic redshift of $z=5.857$, in agreement with the galaxys redshift constraints from multi-wavelength photometry. This would make this object the highest redshift 3mm-selected galaxy and one of the highest redshift dusty star-forming galaxies known to-date. Here, I report the characteristics of this tentative detection and the physical properties that can be inferred assuming the line is real. Finally, I advocate for follow-up observations to corroborate this identification and to confirm the high-redshift nature of this optically-dark dusty star-forming galaxy.
We searched for star formation activity associated with high-z Damped Lyman-alpha systems (DLAs) with Subaru telescope. We used a set of narrow-band (NB) filters whose central wavelengths correspond to the redshifted Lyman-alpha emission lines of targeted DLA absorbers at 3<z<4.5. We detected one apparent NB-excess object located 3.80 arcsec (~28kpc) away from the quasar SDSS J031036.84+005521.7. Follow-up spectroscopy revealed an asymmetric Lyman-alpha emission at z_em=3.115+/-0.003, which perfectly matches the sub-DLA trough at z_abs=3.1150 with logN(HI)/cm^-2=20.05. The Lyman-alpha luminosity is estimated to be L(LyA)=1.07x10^42 erg s^-1, which corresponds to a star formation rate of 0.97 M_odot yr^-1. Interestingly, the detected Lyman-alpha emission is spatially extended with a sharp peak. The large extent of the Lyman-alpha emission is remarkably one-sided toward the quasar line-of-sight, and is redshifted. The observed spatially asymmetric surface brightness profile can be qualitatively explained by a model of a DLA host galaxy, assuming a galactic outflow and a clumpy distribution of HI clouds in the circumgalactic medium. This large Lyman-alpha extension, which is similar to those found in Rauch et al. (2008), could be the result of complicated anisotropic radiative transfer through the surrounding neutral gas embedded in the DLA.
We present the first spectroscopic measurements of the [OIII] 5007 A line in two z ~ 3.1 Lyman-alpha emitting galaxies (LAEs) using the new near-infrared instrument LUCIFER1 on the 8.4m Large Binocular Telescope (LBT). We also describe the optical imaging and spectroscopic observations used to identify these Lya emitting galaxies. Using the [OIII] line we have measured accurate systemic redshifts for these two galaxies, and discovered a velocity offset between the [OIII] and Ly-alpha lines in both, with the Lya line peaking 342 and 125 km/s redward of the systemic velocity. These velocity offsets imply that there are powerful outflows in high-redshift LAEs. They also ease the transmission of Lya photons through the interstellar medium and intergalactic medium around the galaxies. By measuring these offsets directly, we can refine both Lya-based tests for reionization, and Lya luminosity function measurements where the Lya forest affects the blue wing of the line. Our work also provides the first direct constraints on the strength of the [OIII] line in high-redshift LAEs. We find [OIII] fluxes of 7 and 36 x 10^-17 erg s^-1 cm^-2 in two z ~ 3.1 LAEs. These lines are strong enough to dominate broad-band flux measurements that include the line (in thiscase, K_s band photometry). Spectral energy distribution fits that do not account for the lines would therefore overestimate the 4000 A (and/or Balmer) break strength in such galaxies, and hence also the ages and stellar masses of such high-z galaxies.
We present CO J=4-3 line and 3 mm dust continuum observations of a 100 kpc-scale filamentary Ly{alpha} nebula (SSA22 LAB18) at z=3.1 using the Atacama Large Millimeter/submillimeter Array (ALMA). We detected the CO J=4-3 line at a systemic z(CO)=3.093 {pm} 0.001 at 11 {sigma} from one of the ALMA continuum sources associated with the Ly{alpha} filament. We estimated the CO J=4-3 luminosity of LCO(4-3)=(2.3pm0.2)x10^9 K km s^{-1} pc^2 for this CO source, which is one order of magnitude smaller than those of typical z>1 dusty star-forming galaxies (DSFGs) of similar far-infrared luminosity L(IR)~10^{12} Lsun. We derived a molecular gas mass of Mgas=(4.4^{+0.9}_{-0.6})x10^9 Msun and a star-formation rate of SFR=270pm160 Msun yr^{-1}. We also estimated a gas depletion time of {tau}(dep)=17pm10 Myr, being shorter than those of typical DSFGs. It is suggested that this source is in a transition phase from DSFG to a gas-poor, early-type galaxy. From ALMA to Herschel multi-band dust continuum observations, we measured a dust emissivity index {beta}=2.3pm0.2, which is similar to those of local gas-poor, early-type galaxies. Such a high {beta} can be reproduced by specific chemical compositions for interstellar dust at the submillimeter wavelengths from recent laboratory experiments. ALMA CO and multi-band dust continuum observations can constrain the evolutionary stage of high-redshift galaxies through {tau}(dep) and {beta}, and thus we can investigate dust chemical compositions even in the early Universe.
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