J/A+A/610/A53 Strong lensing star-forming galaxies with ALMA (Massardi+, 2018)
Chandra and ALMA observations of the nuclear activity in two strongly lensed
star-forming galaxies.
Massardi M., Enia A.F.M., Negrello M., Mancuso C., Lapi A., Vignali C.,
Gilli R., Burkutean S., Danese L., De Zotti G.
<Astron. Astrophys. 610, A53 (2018)>
=2018A&A...610A..53M 2018A&A...610A..53M (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, radio ; Gravitational lensing
Keywords: galaxies: active - gravitational lensing: strong -
submillimeter: galaxies - galaxies: evolution - X-rays: galaxies
Abstract:
According to coevolutionary scenarios, nuclear activity and star
formation play relevant roles in the early stages of galaxy formation.
We aim at identifying them in high-redshift galaxies by exploiting
high-resolution and high-sensitivity X-ray and millimeter-wavelength
data to confirm the presence or absence of star formation and nuclear
activity and describe their relative roles in shaping the spectral
energy distributions and in contributing to the energy budgets of the
galaxies.
We present the data, model, and analysis in the X-ray and millimeter
(mm) bands for two strongly lensed galaxies, SDP.9 (HATLAS
J090740.0-004200) and SDP.11 (HATLAS J091043.1-000322), which we
selected in the Herschel-ATLAS catalogs for their excess emission in
the mid-IR regime at redshift ≥1.5. This emission suggests nuclear
activity in the early stages of galaxy formation. We observed both of
them with Chandra ACIS-S in the X-ray regime and analyzed the
high-resolution mm data that are available in the ALMA Science Archive
for SDP.9. By combining the information available in mm, optical, and
X-ray bands, we reconstructed the source morphology.
Both targets were detected in the X-ray, which strongly indicates
highly obscured nuclear activity. ALMA observations for SDP.9 for the
continuum and CO(6-5) spectral line with high resolution (0.02-arcsec
corresponding to ∼65pc at the distance of the galaxy) allowed us to
estimate the lensed galaxy redshift to a better accuracy than pre-ALMA
estimates (1.5753±0.0003) and to model the emission of the optical,
millimetric, and X-ray band for this galaxy. We demonstrate that the
X-ray emission is generated in the nuclear environment, which strongly
supports that this object has nuclear activity. On the basis of the
X-ray data, we attempt an estimate of the black hole properties in
these galaxies.
By taking advantage of the lensing magnification, we identify weak
nuclear activity associated with high-z galaxies with high star
formation rates. This is useful to extend the investigation of the
relationship between star formation and nuclear activity to two
intrinsically less luminous high-z star-forming galaxies than was
possible so far. Given our results for only two objects, they alone
cannot constrain the evolutionary models, but provide us with
interesting hints and set an observational path toward addressing the
role of star formation and nuclear activity in forming galaxies.
Description:
We present high-resolution (<0.1arcsec) observations of SDP.9 (HATLAS
J090740.0-004200), made with ALMA.
Objects:
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RA (2000) DE Designation(s)
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09 07 40.0 -00 42 00 SDP 9 = H-ATLAS J090740.0-004200
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 139 2 List of fits files
fits/* . 2 Individual fits files
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 23 I4 --- Nx Number of pixels along X-axis
25- 28 I4 --- Ny Number of pixels along Y-axis
30- 31 I2 --- Nz ? Number of slides
33- 55 A23 --- Obs.date Observation date
57- 63 F7.3 GHz Freq Observed frequency or lower value of
frequency interval for the datacube
65- 71 F7.3 GHz BFreq ? Upper value of frequency interval for the
datacube
73- 83 E11.6 Hz dFreq ? Frequency resolution for the datacube
85- 90 I6 Kibyte size Size of FITS file
92-105 A14 --- FileName Name of FITS file, in subdirectory fits
107-139 A33 --- Title Title of the FITS file
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Acknowledgements:
Marcella Massardi, massardi(at)ira.inaf.it
(End) Patricia Vannier [CDS] 09-Mar-2018