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J/A+A/611/A22  Jekyll & Hyde galaxies ALMA cube & spectrum    (Schreiber+, 2018)

Jekyll & Hyde: quiescence and extreme obscuration in a pair of massive galaxies 1.5 Gyr after the Big Bang. Schreiber C., Labbe I., Glazebrook K., Bekiaris G., Papovich C., Costa T., Elbaz D., Kacprzak G.G., Nanayakkara T., Oesch P., Pannella M., Spitler L., Straatman C., Tran K.-V., Wang T. <Astron. Astrophys. 611, A22 (2018)> =2018A&A...611A..22S (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, spectra ; Spectra, millimetric/submm Keywords: galaxies: evolution - galaxies: high-redshift - galaxies: kinematics and dynamics - galaxies: star formation - galaxies: stellar content - submillimeter: galaxies Abstract: We obtained ALMA spectroscopy and deep imaging to investigate the origin of the unexpected sub-millimeter emission toward the most distant quiescent galaxy known to date, ZF-COSMOS-20115 at z=3.717. We show here that this sub-millimeter emission is produced by another massive (M*∼1011M), compact (r1/2=0.67±0.14kpc) and extremely obscured galaxy (AV∼3.5), located only 0.4300 (3.1kpc) away from the quiescent galaxy. We dub the quiescent and dusty galaxies Jekyll and Hyde, respectively. No dust emission is detected at the location of the quiescent galaxy, implying SFR<13M/yr which is the most stringent upper limit ever obtained for a quiescent galaxy at these redshifts. The two sources are spectroscopically confirmed to lie at the same redshift thanks to the detection of [CII]158 in Hyde (z=3.709), which provides one the few robust redshifts for a highly-obscured "H-dropout" galax (H-[4.5]=5.1±0.8). The [CII] line shows a clear rotating-disk velocity profile which is blueshifted compared to the Balmer lines of Jekyll by 549±60km/s, demonstrating that it is produced by another galaxy. Careful de-blending of the Spitzer imaging confirms the existence of this new massive galaxy, and its non-detection in the Hubble images requires extremely red colors and strong attenuation by dust. Full modeling of the UV-to-far-IR emission of both galaxies shows that Jekyll has fully quenched at least 200Myr prior to observation and still presents a challenge for models, while Hyde only harbors moderate star-formation with SFR≲120M_☉/yr, and is located at least a factor 1.4 below the z∼4 main sequence. Hyde could also have stopped forming stars less than 200Myr before being observed; this interpretation is also suggested by its compactness comparable to that of z∼4 quiescent galaxies and its low [CII]/FIR ratio, but significant on-going star-formation cannot be ruled out. Lastly, we find that despite its moderate SFR, Hyde hosts a dense reservoir of gas comparable to that of the most extreme starbursts. This suggests that whatever mechanism has stopped or reduced its star-formation must have done so without expelling the gas outside of the galaxy. Because of their surprisingly similar mass, compactness, environment and star-formation history, we argue that Jekyll and Hyde can be seen as two stages of the same quenching process, and provide a unique laboratory to study this poorly understood phenomenon. Description: These files consist of the full ALMA data cube for the galaxies Jekyll and Hyde, together with the extracted continuum image and the spectrum of Hyde. The data cube was produced by CASA (v4.7.0), the continuum image was constructed as the weighted average in line-free channels, and the spectrum was extracted at the peak flux position of Hyde. The data cube and spectrum files contain two extensions, one for the flux, and another for the uncertainty. This uncertainty was determined from the RMS of the cube data between 2 and 8" away from the center. All fluxes are in units of Jansky, and the spectral axis is given in observed frequency (GHz). The images were not CLEANed, therefore the dirty beam (which is also provided here) is the correct point-spread function to use when analyzing these images. Objects: ---------------------------------------------------------------------- RA (2000) DE Designation(s) ---------------------------------------------------------------------- 10 00 14.7620 +02 22 43.270 Jekyll & Hyde = [SLS2014] ZF-COSMOS-13172 ---------------------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file list.dat 109 4 List of fits files fits/* 0 4 Individual fits files
Byte-by-byte Description of file: list.dat
Bytes Format Units Label Explanations
1- 9 F9.5 deg RAdeg Right Ascension of center (J2000) 10- 18 F9.5 deg DEdeg Declination of center (J2000) 20- 22 I3 --- Nx Number of pixels along X-axis 24- 26 I3 --- Ny ? Number of pixels along Y-axis 28- 30 I3 --- Nz ? Number of slices (for the data cude) 32- 53 A22 --- Obs.Date Observation date ( 55- 57 I3 GHz bFreq ? Lower value of frequency interval 59- 65 F7.3 GHz BFreq ? Upper value of frequency interval 67- 75 F9.7 GHz dFreq ? Frequency resolution 77- 80 I4 Kibyte size Size of FITS file 82- 90 A9 --- FileName Name of FITS file, in subdirectory fits 92-109 A18 --- Title Title of the FITS file
Acknowledgements: Corentin Schreiber, cschreib(at)
(End) Patricia Vannier [CDS] 14-Dec-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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