Alexandre Beelen @ IAS - Publications

CNAP Application

2009-06-02T00:00:00+02:00

After the success of my application to the Conseil National Des Astronomes et Physiciens -- Section Astronomie, you can find my complete application below

Beelen_Alexandre.pdf (664kb)

LABoCa observation of the Francis Cluster

2008-06-02T00:00:00+02:00

Beelen, A.; Omont, A.; Bavouzet, N.; Kovács, A.; Lagache, G.; De Breuck, C.; Weiss, A.; Menten, K. M.; Colbert, J. W.; Dole, H.; Siringo, G.; Kreysa, E.

We present observations aimed at exploring both the nature of Ly-α emitting nebulae ("Ly-α blos") at \(z=2.38\) and the way they trace large scale structure, by exploring their proximity to "maximum starbursts" through submillimeter emission. Our most important objectives are to make a census of associated submillimeter galaxies (SMGs), check their properties, and look for a possible overdensity in the protocluster J2142-4426 at \(z=2.38\). We used the newly commissioned Large APEX Bolometer Camera (LABoCa) on the Atacama Pathfinder EXperiment (APEX) telescope, in its Science Verification phase, to carry out a deep 10 arcmin x arcmin map at 870 µm, and we performed multiple checks of the quality of data processing and source extraction. Our map, the first published deep image, confirms the capabilities of APEX/LABoCa as the most efficient current equipment for wide and deep submm mapping. Twenty-two sources were securely extracted with 870 µm flux densities in the range 3-21 mJy, rms noise 0.8-2.4 mJy, and far-IR luminosities probably in the range \(5-20 \times 10^{12}\ \mathrm{L_\odot}\). Only one of the four 50 kpc-extended Ly-α blobs has a secure 870 µm counterpart. The 870 µm source counts in the whole area are marginally higher than in the SHADES SCUBA survey, with a possible over-density around this blob. The majority of the 3.6-24 µm SEDs of the submillimeter sources indicate they are starburst dominated, with redshifts mostly ≥ 2. However, there is evidence of a high-z AGN in 30\% of the sources.

Accepted for publication in AandA, Volume 423, Pages 485-645 (2008).

Find this paper on ADS under the reference 2008A&A...485..645B, or on the arXiv service under the reference arXiv:0803.1615.

LABoCa map of the Francis Cluster reduced by BoA :
- J2142-4426_LABoCa.fits.gz (292kb)
Table 1 of the paper : LABoCa source list :
- J2142-4426_LABoCa_table1.votable (8kb)

350 Micron Emission from High-z QSOs

2006-06-02T00:00:00+02:00

Beelen, A.; Cox, P.; Benford, D.J.; Dowell, C.D.; Kovacs, A.; Bertoldi, F.; Omont, A.; Carilli, C.L.

We report detections of six high-redshift (\(1.8~<~z~<~6.4\)), optically luminous, radio-quiet quasars at 350 µm, using the SHARC II bolometer camera at the Caltech Submillimeter Observatory. Our observations double the number of high-redshift quasars for which 350 µm photometry is available. By combining the 350 µm measurements with observations at other submillimeter/millimeter wavelengths, for each source we have determined the temperature of the emitting dust (ranging from 40 to 60 K) and the far-infrared luminosity (\(0.6\) to \(2.2~\times~10^{13}\ \mathrm{L_\odot}\)). The combined mean spectral energy distribution (SED) of all high-redshift quasars with two or more rest frame far-infrared photometric measurements is best fit with a greybody with temperature of 47 ± 3 K and a dust emissivity power-law spectral index of \(\beta~=~1.6~\pm~0.1\). This warm dust component is a good tracer of the starburst activity of the quasar host galaxy. The ratio of the far-infrared to radio luminosities of infrared luminous, radio-quiet high-redshift quasars is consistent with that found for local star-forming galaxies.

Accepted for publication in ApJ, Volumne 642, Issue 2, pp. 694-701. Find this paper on ADS under the reference 2006ApJ...642..694B, or on the arXiv service under the reference astro-ph/0603121.

Fits files produced by CRUSH for the 350 µm observations made with SHARC II of the 6 sources published in this paper
- 350mu_fits.tar.bz2 (1.3Mo)

Dust & Gas in High-z QSOs - PhD Thesis

2004-06-02T00:00:00+02:00

Beelen, A.

This thesis presents the study of dust and gas in high redshift quasars (QSOs) based on (sub)millimeter and radio observations. The surveys of the infrared and radio continuum of optically luminous and radio-quiet QSOs at \(1.9 < z < 6.4\) indicate the presence of large dust masses, including in the \(z > 6\) QSOs. The relationship between infrared and radio emission sfolowed by local galaxies is also found for the high-z QSOs, suggesting that the dust heating is dominated by young massive stars. These studies have allowed us to derive a relationship between the black hole and star formation activity. The high star formation rates (\(\approx 1000\ \mathrm{M_\odot/yr}\)) point to intense starbursts which have to be sustained by massive reservoirs of molecular gas. The detection of CO in J1409+5628 at z=2.56 in described in detail and a global study of the CO emission in high-z sources is presented. In a few cases, the detection of several CO transitions enables to constrain the physical conditions, indicating gas temperatures of 60-100 K, and densities of \(10^{3-4}\ \mathrm{cm^{-3}}\), comparable to what is found in M82 and Arp220. Finally, the detection of CI and HCN is reported in two high-z QSOs. | These studies have allowed us to constrain the physical conditions in the host galaxies of high-z QSOs, among the most massive objects in the universe. These exploratory studies, which open the way to the study of the interstellar medium in the extreme environments of the first galaxies, will come to full maturity when the satellite Herschel and the interferometers eVLA and ALMA will be operational.

You can find my thesis on line on multidisciplinary theses server under the reference tel-00011634. You can find the abstract on ADS under the reference 2004PhDT........43B.

My phd thesis in postscript (french) :
- phd_beelen.ps.bz2 (8.1Mo)
My phd thesis in pdf (french) :
- phd_beelen.pdf (5.4Mo)
My thesis defense (french) :
- 2004-12-07 @ IAS phd_defense.pdf (3.4Mo)

Starburst activity in J1409+5628

2004-06-02T00:00:00+02:00

Beelen, A.; Cox, P.; Pety, J.; Carilli, C. L.; Bertoldi, F.; Momjian, E.; Omont, A.; Petitjean, P.; Petric, A. O.

We report the detection of CO emission from the optically luminous, radio-quiet quasar J140955.5+562827, at a redshift \(z_{CO}~=~2.583\). We also present VLA continuum maps and VLBA high spatial resolution observations at 1.4 GHz. Both the CO(3→2) and CO(7→6) emission lines are detected using the IRAM Plateau de Bure interferometer. The 3→2/7→6 line luminosity ratio is about 1/3, indicating the presence of warm and dense molecular gas with an estimated mass of \(6\times10^{10}\ \mathrm{M_\odot}\). The infrared-to-CO luminosity ratio \(L_\mathrm{FIR}/L^\prime_\mathrm{CO(1\to0)} \sim 500\ \mathrm{L_\odot (K km s^{-1} pc^2)^{-1}}\), comparable to values found for other high-z sources where CO line emission is seen. J1409+5628 is detected using the VLA with a 1.4 GHz rest-frame luminosity density of \(4.0\times10^{25}\ \mathrm{W Hz^{-1}}\). The rest-frame radio to far-infrared ratio, q, has a value of 2.0 which is similar to the values found in star forming galaxies. At the 30 mas resolution of the VLBA, J1409+5628 is not detected with a 4σ upper limit to the surface brightness of \(0.29 mJy beam^{-1}\). This implies a limit to the intrinsic brightness temperature of \(2\times10^{5}\ \mathrm{K}\) at 8 GHz, typical for nuclear starbursts and more than two orders of magnitude fainter than typical radio-loud active galactic nuclei. Both the properties of the CO line emission and the radio emission from J1409+5628 are therefore consistent with those expected for a star forming galaxy. In J1409+5628 young massive stars are the dominant source of dust heating, accounting for most of the infrared luminosity. The massive reservoir of molecular gas can sustain the star formation rate of a few \(1000\ \mathrm{M_\odot yr^{-1}}\) implied by the far-infrared luminosity for about 10 million years.

Accepted for publication by AandA, Volume 423, Pages 441-447 (2004).

Find this paper on ADS under the reference 2004A&A...423..441B, or on the arXiv service under the reference astro-ph/0404172.

Calibrated UV Table of the CO(3→2) observation of J1409+5628 obtained at the PdBI :
- J1409+5628_PdB_CO32.uvt.bz2 (4.0Mo)
Observation at 1.4 GHz of J1409+5628 obtained with the Very Large Array :
- J1409+5628_VLA_1.4GHz.fits.bz2 (1.0Mo)