J/A+A/614/A33 500µm-risers sources (Donevski+, 2018)
Towards a census of high-redshift dusty galaxies with Herschel.
A selection of "500 µm-risers".
Donevski D., Buat V., Boone F., Pappalardo C., Bethermin M., Schreiber C.,
Mazyed F., Alvarez-Marquez J., Duivenvoorden S.
<Astron. Astrophys., 614, A33 (2018)>
=2018A&A...614A..33D 2018A&A...614A..33D (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, IR ; Photometry, millimetric/submm
Keywords: infrared: galaxies
Abstract:
Context. Over the last decade a large number of dusty star-forming
galaxies has been discovered up to redshift z=2-3 and recent studies
have attempted to push the highly confused Herschel SPIRE surveys
beyond that distance. To search for z≥4 galaxies they often consider
the sources with fluxes rising from 250µm to 500µm (so-called
"500µm-risers"). Herschel surveys offer a unique opportunity to
efficiently select a large number of these rare objects, and thus gain
insight into the prodigious star-forming activity that takes place in
the very distant Universe. Aims. We aim to implement a novel method to
obtain a statistical sample of 500µm-risers and fully evaluate our
selection inspecting different models of galaxy evolution. Methods. We
consider one of the largest and deepest Herschel surveys, the Herschel
Virgo Cluster Survey. We develop a novel selection algorithm which
links the source extraction and spectral energy distribution fitting.
To fully quantify selection biases we make end-to-end simulations
including clustering and lensing. Results. We select 133
500µm-risers over 55deg2, imposing the criteria:
S500>S350>S250, S250>13.2mJy and S500>30mJy. Differential
number counts are in fairly good agreement with models, displaying a
better match than other existing samples. The estimated fraction of
strongly lensed sources is 24+6-5% based on models.Conclusions. We
present the faintest sample of 500µm-risers down to S250=13.2mJy.
We show that noise and strong lensing have an important impact on
measured counts and redshift distribution of selected sources. We
estimate the flux-corrected star formation rate density at 4<z<5 with
the 500µm-risers and find it to be close to the total value
measured in far-infrared. This indicates that colour selection is not
a limiting effect to search for the most massive, dusty z>4 sources.
Description:
We have performed a systematic search of dusty background galaxies on
a 55deg2 area. We introduce an innovative method for selecting
500um-risers (S500>S350>S250). In order to estimate the 250-500um
flux of blended sources, we use the multiwavelength MBB-fitter code.
We assign positions of galaxies detected in the 250um map as a prior
to extracting the flux densities at longer wavelengths, iteratively
fitting their SEDs as modified blackbodies. We select 133 500um-risers
that fulfil the following criteria: S500>S350>S250, S250> 13.2mJy and
S500>30mJy.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tabled1.dat 79 133 Selected sources
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Byte-by-byte Description of file: tabled1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID [1/133] Sequential number
5- 22 A18 --- Name Source name (HVS JHHMMSS+DDMM.s)
24- 25 I2 h RAh Right ascension (J2000)
27- 28 I2 min RAm Right ascension (J2000)
30- 34 F5.2 s RAs Right ascension (J2000)
36 A1 --- DE- Declination sign (J2000)
37- 38 I2 deg DEd Declination (J2000)
40- 41 I2 arcmin DEm Declination (J2000)
43- 46 F4.1 arcsec DEs Declination (J2000)
48- 52 F5.2 mJy S250 SPIRE flux at 250um
54- 57 F4.2 mJy e_S250 rms uncertainty on S250 (1)
59- 63 F5.2 mJy S350 SPIRE flux at 350um
65- 68 F4.2 mJy e_S350 rms uncertainty on S350 (1)
70- 74 F5.2 mJy S500 SPIRE flux at 500um
76- 79 F4.2 mJy e_S500 rms uncertainty on S250 (1)
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Note (1): Flux errors are estimated as explained in Sect. 2.6. We note, however,
that errors are strongly correlated, since we performed "forced" MBB
photometry at SPIRE wavelengths.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 29-Aug-2018