Max-Planck Millimeter Bolometer Research Articles

Dynamical Timescale of Pre-collapse Evolution Inferred from Chemical Distribution in the Taurus Molecular Cloud-1 (TMC-1) Filament

Abstract We present observations and analyses of the low-mass star-forming region, Taurus Molecular Cloud-1 (TMC-1). CS (J = 2–1)/N2H+ (J = 1–0) and C17O (J = 2–1)/C18O (J = 2–1) were observed with the Five College Radio Astronomy Observatory and the Seoul Radio Astronomy Observatory, respectively. In addition, Spitzer infrared data and 1.2 mm continuum data observed with Max-Planck Millimetre Bolometer are used. We also perform chemical modeling to investigate the relative molecular distributions of the TMC-1 filament. Based on Spitzer observations, there is no young stellar object along the TMC-1 filament, while five Class II and one Class I young stellar objects are identified outside the filament. The comparison between column densities calculated from dust continuum and C17O 2–1 line emission shows that CO is depleted much more significantly in the ammonia peak than in the cyanopolyyne peak, while the column densities calculated from the dust continuum are similar at the two peaks. N2H+ is not depleted much in either peak. According to our chemical calculation, the differential chemical distribution in the two peaks can be explained by different timescales required to reach the same density, i.e., by different dynamical processes.

The Canada-France High-zQuasar Survey: 1.2 mm observations

We report 250 GHz (1.2 mm) observations of a sample of 20 QSOs at redshifts 5.8<z<6.5 from the the Canada-France High-z Quasar Survey (CFHQS), using the Max-Planck Millimeter Bolometer (MAMBO) array at the IRAM 30-metre telescope. A rms sensitivity <~ 0.6 mJy was achieved for 65% of the sample, and <~ 1.0 mJy for 90%. Only one QSO, CFHQS J142952+544717, was robustly detected with S_250GHz = 3.46 +/-0.52 mJy. This indicates that one of the most powerful known starbursts at z~6 is associated with this radio loud QSO. On average, the other CFHQS QSOs, which have a mean optical magnitude fainter than previously studied SDSS samples of z~6 QSOs, have a mean 1.2 mm flux density <S_250GHz> = 0.41 +/-0.14 mJy; such a 2.9-sigma average detection is hardly meaningful. It would correspond to <L_FIR> ~ 0.94+/-0.32 10^12 Lo, and an average star formation rate of a few 100's Mo/yr, depending on the IMF and a possible AGN contribution to <L_FIR>. This is consistent with previous findings of Wang et al. (2011) on the far-infrared emission of z~6 QSOs and extends them toward optically fainter sources.

A DEEP 1.2 mm MAP OF THE LOCKMAN HOLE NORTH FIELD

We present deep 1.2 mm continuum mapping of a 566 arcmin^2 area within the Lockman Hole North field, previously a target of the Spitzer Wide-area Infrared Extragalactic (SWIRE) survey and extremely deep 20 cm mapping with the Very Large Array, which we have obtained using the Max-Planck millimeter bolometer (MAMBO) array on the IRAM 30 m telescope. After filtering, our full map has an RMS sensitivity ranging from 0.45 to 1.5 mJy/beam, with an average of 0.75 mJy/beam. Using the pixel flux distribution in a map made from our best data, we determine the shape, normalization, and approximate flux density cutoff for 1.2 mm number counts well below our nominal sensitivity and confusion limits. After validating our full dataset through comparison with this map, we successfully detect 41 1.2 mm sources with S/N > 4.0 and S(1.2 mm)\simeq 2-5 mJy. We use the most significant of these detections to directly determine the integral number counts down to 1.8 mJy, which are consistent with the results of the pixel flux distribution analysis. 93% of our 41 individual detections have 20 cm counterparts, 49% have Spitzer/MIPS 24 micron counterparts, and one may have a significant Chandra X-ray counterpart. We resolve \simeq 3% of the cosmic infrared background (CIB) at 1.2 mm into significant detections, and directly estimate a 0.05 mJy faint-end cutoff for the counts that is consistent with the full intensity of the 1.2 mm CIB. The median redshift of our 17 detections with spectroscopic or robust photometric redshifts is z(median)=2.3, and rises to z(median)=2.9 when we include redshifts estimated from the radio/far-infrared spectral index. By using a nearest neighbor and angular correlation function analysis, we find evidence that our S/N>4.0 detections are clustered at the 95% confidence level.

IDENTIFICATION OF TWO BRIGHT z &gt; 3 SUBMILLIMETER GALAXY CANDIDATES IN THE COSMOS FIELD

We present high-resolution interferometric Submillimeter Array (SMA) imaging at 890 microns (~2" resolution) of two millimeter selected galaxies -- MMJ100015+021549 and MMJ100047+021021 -- discovered with the Max-Planck Millimeter Bolometer (MAMBO) on the IRAM 30 m telescope and also detected with Bolocam on the CSO, in the COSMOS field. The first source is significantly detected at the ~11 sigma level, while the second source is tentatively detected at the ~4 sigma level, leading to a positional accuracy of ~0.2-0.3". MM100015+021549 is identified with a faint radio and K-band source. MMJ100047+021021 shows no radio emission and is tentatively identified with a very faint K-band peak which lies at ~1.2" from a clumpy optical source. The submillimeter-to-radio flux ratio for MM100015+021549 yields a redshift of ~4.8, consistent with the redshift implied by the UV-to-submillimeter photometry, z~3.0-5.0. We find evidence for warm dust in this source with an infrared luminosity in the range ~0.9-2.5x10^{13} L_sun, supporting the increasing evidence for a population luminous submillimeter galaxies at z>3. Finally, the lack of photometric data for MMJ100047+021021 does not allow us to investigate its properties in detail, however its submillimeter-to-radio ratio implies z>3.5.

MAMBO observations at 240 GHz of optically obscuredSpitzersources: source clumps and radio activity at high redshift

Optically very faint (R > 25.5) sources detected by the Spitzer Space Telescope at 24 μm represent a very interesting population at redshift z∼ (1.5–3). They exhibit strong clustering properties, implying that they are hosted by very massive haloes, and their mid-infrared emission could be powered by either dust-enshrouded star formation and/or by an obscured active galactic nucleus (AGN). We report observations carried out with the Max Planck Millimetre Bolometer (MAMBO) array at the IRAM 30-m antenna on Pico Veleta of a candidate protocluster with five optically obscured sources selected from the 24-μm Spitzer sample of the First-Look Survey. Interestingly, these sources appear to lie on a high-density filament aligned with the two radio jets of an AGN. Four out of five of the observed sources were detected. We combine these measurements with optical, infrared and radio observations to probe the nature of the candidate protocluster members. Our preliminary conclusions can be summarized as follows: the spectral energy distributions (SEDs) of all sources include both AGN and starburst contributions; the AGN contribution to the bolometric luminosities ranges between 14 and 26 per cent of the total. Such a contribution is enough for the AGN to dominate the emission at 5.8, 8 and 24 μm, while the stellar component, inferred from SED fitting, prevails at 1.25 mm and at λ < 4.5 μm. The present analysis suggests a coherent interplay at high z between extended radio activity and the development of filamentary large-scale structures.

The evolution of star formation in quasar host galaxies

We have used far-infrared data from IRAS, ISO, SWIRE, SCUBA and MAMBO to constrain statistically the mean far-infrared luminosities of quasars. Our quasar compilation at redshifts 0<z<6.5 and I-band luminosities -20<I(AB)<-32 is the first to distinguish evolution from quasar luminosity dependence in such a study. We carefully cross-calibrate IRAS against Spitzer and ISO, finding evidence that IRAS 100um fluxes at <1Jy are overestimated by ~30%. We find evidence for a correlation between star formation in quasar hosts and the quasar optical luminosities, varying as SFR proportional to L_opt^(0.44+/-0.07) at any fixed redshift below z=2. We also find evidence for evolution of the mean star formation rate in quasar host galaxies, scaling as (1+z)^(1.6+/-0.3) at z<2 for any fixed quasar I-band absolute magnitude fainter than -28. We find no evidence for any correlation between star formation rate and black hole mass at 0.5<z<4. Our data are consistent with feedback from black hole accretion regulating stellar mass assembly at all redshifts.

A 1200-μm MAMBO survey of the GOODS-N field: a significant population of submillimetre dropout galaxies

We present a 1200-mu m image of the Great Observatories Origin Deep Survey North (GOODS-N) field, obtained with the Max Planck Millimetre Bolometer array (MAMBO) on the IRAM 30-m telescope. The survey covers a contiguous area of 287 arcmin(^2) to a near-uniform noise level of similar to 0.7mJy beam(^-1). After Bayesian flux deboosting, a total of 30 sources are recovered (>= 3.5 sigma). An optimal combination of our 1200-mu m data and an existing 850-mu m image from the Submillimetre Common-User Bolometer Array (SCUBA) yielded 33 sources (>= 4 sigma). We combine our GOODS-N sample with those obtained in the Lockman Hole and ELAIS N2 fields (Scott et al. 2002; Greve et al. 2004) in order to explore the degree of overlap between 1200-and 850-mu m-selected galaxies (hereafter SMGs), finding no significant difference between their S-850 mu m/S-1200 mu m distributions. However, a noise-weighted stacking analysis yields a significant detection of the 1200-mu m-blank SCUBA sources, S-850 mu m/S-1200 mu m = 3.8 +/- 0.4, whereas no significant 850-mu m signal is found for the 850-mu m-blank MAMBO sources (S-850 mu m/S-1200 mu m = 0.7 +/- 0.3). The hypothesis that the S-850 mu m/S-1200 mu m distribution of SCUBA sources is also representative of the MAMBO population is rejected at the similar to 4 sigma level, via Monte Carlo simulations. Therefore, although the populations overlap, galaxies selected at 850 and 1200 mu m are different, and there is compelling evidence for a significant 1200-mu m-detected population which is not recovered at 850 mu m. These are submillimetre dropouts (SDOs), with S-850 mu m/S-1200 mu m = 0.7-1.7, requiring very cold dust or unusual spectral energy distributions (T-d similar or equal to 10 K; beta similar or equal to 1), unless SDOs reside beyond the redshift range observed for radio-identified SMGs, i. e. at z > 4.

Millimetric properties of gamma-ray burst host galaxies

We present millimetre (mm) and submillimetre (submm) photometry of a sample of five host galaxies of gamma-ray bursts (GRBs), obtained using the Max Planck Millimetre Bolometer (MAMBO2) array and Submillimetre Common-User Bolometer Array (SCUBA). These observations were obtained as part of an ongoing project to investigate the status of GRBs as indicators of star formation. Our targets include two of the most unusual GRB host galaxies, selected as likely candidate submm galaxies: the extremely red (R−K≈ 5) host of GRB 030115, and the extremely faint (R > 29.5) host of GRB 020124. Neither of these galaxies is detected, but the deep upper limits for GRB 030115 impose constraints on its spectral energy distribution, requiring a warmer dust temperature than is commonly adopted for submillimetre galaxies (SMGs). As a framework for interpreting these data, and for predicting the results of forthcoming submm surveys of Swift-derived host samples, we model the expected flux and redshift distributions based on luminosity functions of both submm galaxies and GRBs, assuming a direct proportionality between the GRB rate density and the global star formation rate density. We derive the effects of possible sources of uncertainty in these assumptions, including (1) introducing an anticorrelation between GRB rate and the global average metallicity, and (2) varying the dust temperature.

A Fluctuation Analysis of the Bolocam 1.1 mm Lockman Hole Survey

We perform a fluctuation analysis of the 1.1 mm Bolocam Lockman Hole Survey, which covers 324 arcmin2 to a very uniform point-source-filtered rms noise level of σ 1.4 mJy beam-1. The fluctuation analysis has the significant advantage of using all of the available data, since no extraction of sources is performed: direct comparison is made between the observed pixel flux density distribution [P(D)] and the theoretical distributions for a broad range of power-law number count models, n(S) = n0S-δ. We constrain the number counts in the 1-10 mJy range and derive significantly tighter constraints than in previous work: the power-law index δ = 2.7, while the amplitude is n0 = 1595 mJy-1 , or N(> 1 mJy) = 940 (95% confidence). At flux densities above 4 mJy, where a valid comparison can be made, our results agree extremely well with those derived from the extracted source number counts by Laurent et al.: the best-fitting differential slope is somewhat shallower (δ = 2.7 vs. 3.2), but well within the 68% confidence limit, and the amplitudes (number of sources per square degree) agree to 10%. At 1 mJy, however [the limit of the P(D) analysis], the shallower slope derived here implies a substantially smaller amplitude for the integral number counts than extrapolation from above 4 mJy would predict. Our derived normalization is about 2.5 times smaller than that determined by the Max-Planck Millimeter Bolometer (MAMBO) at 1.2 mm (Greve et al.). However, the uncertainty in the normalization for both data sets is dominated by the systematic (i.e., absolute flux calibration) rather than statistical errors; within these uncertainties, our results are in agreement. Our best-fit amplitude at 1 mJy is also about a factor of 3 below the prediction of Blain et al., but we are in agreement above a few millijanskys. We estimate that about 7% of the 1.1 mm background has been resolved at 1 mJy.

Near‐Infrared Photometry of the High‐Redshift Quasar RD J030117+002025: Evidence for a Massive Starburst atz= 5.5

With a redshift of z = 5.5 and an optical blue magnitude MB ~ -24.2 mag (~4.5 × 1012 L☉), RD J030117+002025 is the most distant, optically faint (MB > -26 mag) quasar known. Max-Planck Millimeter Bolometer (MAMBO) continuum observations at λ = 1.2 mm (185 μm rest frame) showed that this quasar has a far-infrared (FIR) luminosity comparable to its optical luminosity. We present near-infrared J- and K-band photometry obtained with the Near-Infrared Camera (NIRC) on the Keck I telescope, tracing the slope of the rest-frame ultraviolet (UV) spectrum of this quasar. The observed spectral index is close to the value of αν ~ -0.44 measured in composite spectra of optically bright SDSS quasars. It thus appears that the quasar does not suffer from strong dust extinction, which further implies that its low rest-frame UV luminosity is due to an intrinsically faint active galactic nucleus (AGN). The FIR to optical luminosity ratio is then much larger than that observed for the more luminous quasars, supporting the suggestion that the FIR emission is not powered by the AGN but by a massive starburst.

Size estimates of some optically bright KBOs

Seven recently detected optically bright Kuiper-Belt-Objects (KBOs) were observed at 250 GHz using the Max-Planck Millimeter Bolometer (MAMBO) array at the IRAM 30 m telescope. Only the optical binary KBO (47 171) 1999 TC36 was detected, whose components differ optically by ∆m ≈ 2 mag. Assuming that the derived mean geometric albedo of p = 0.05 is identical for both, the component diameters become 566 and 225 km. For the other six objects upper limits to their sizes and lower limits for their albedos were obtained. The geometric albedo, p, for (28978) Ixion is surprisingly large, ≥0.15. For a consistent comparison all published radio photometric data of KBOs and Centaurs were analyzed again: the average geometric albedo is found to be ≈0.08.

Sensitive Observations at 1.4 and 250 GHz ofz&gt;5 QSOs

We present 1.4 and 5 GHz observations taken with the Very Large Array (VLA), and observations at 250 GHz obtained with the Max-Planck millimeter bolometer (MAMBO) at the IRAM 30~m telescope, of ten optically selected Quasi-stellar Objects (QSOs) at 5.0 < z < 6.28. Four sources are detected at 1.4 GHz two of which are radio loud and are also detected at 5 GHz. These results are roughly consistent with there being no evolution of the radio-loud QSO fraction out to z~6. Three sources have been detected at 250 GHz or 350 GHz at much higher levels than their 1.4 GHz flux densities suggesting that the observed mm emission is likely thermal emission from warm dust, although more exotic possibilities cannot be precluded. The highest redshift source in our sample (J1030+0524 at z=6.28) is not detected at 1.4 or 250 GHz, but four fairly bright radio sources (flux density at 1.4GHz > 0.2 mJy) are detected in a 2' field centered on the QSO, including an edge-brightened ('FRII') double radio source with an extent of about 1'. A similar over-density of radio sources is seen in the field of the highest redshift QSO J1148+5251. We speculate that these over-densities of radio sources may indicate clusters along the lines-of-sight, in which case gravitational lensing by the cluster could magnify the QSO emission by a factor 2 or so without giving rise to arcsecond-scale distortions in the optical images of the QSOs.

SCUBA observations of the sources detected in the MAMBO 1200-μm survey

We have observed 23 sources from the Max-Planck Millimetre Bolometer (MAMBO) array 1200-μm survey with SCUBA at 850 μm, detecting 19 of the sources. The sources generally have low values for the ratio of 850- to 1200-μm flux. Two possible explanations for the low values are either that the sources are at very high redshifts or that the global properties of the dust in the MAMBO sources are different from the global properties of dust in low-redshift galaxies. If the former explanation is correct, we estimate that 15 of the MAMBO sources lie at z > 3.

A 1.2 mm MAMBO/IRAM–30 m study of dust emission from optically luminous $z \approx$ 2 quasars

We report 250 GHz (1.2 mm) observations of redshift optically luminous (), radio quiet quasars using the Max-Planck Millimeter Bolometer (MAMBO) array at the IRAM 30-metre telescope. Nine quasars were detected and for 26 quasars 3 flux density limits in the range 1.8 to 4 mJy were obtained. Adopting a typical dust temperature of 45 K, the millimeter emission implies far-infrared luminosities of order and dust masses of ∼10. Applying a statistical survival analysis to our total sample of 43 detected and 95 undetected quasars at and , we find that there is no apparent difference in the far-infrared (FIR) luminosities, hence the star formation rates, of QSOs at and at . This differs from radio galaxies, for which the FIR luminosity was found to increase with redshift (Archibald et al. 2001). We furthermore find that there is no strong correlation between the far-infrared and optical luminosities, confirming previous results obtained on smaller samples.

Breaking the 'redshift deadlock'- I. Constraining the star formation history of galaxies with submillimetre photometric redshifts

Future extragalactic submillimetre and millimetre surveys have the potential to provide a sensitive census of the level of obscured star formation in galaxies at all redshifts. While in general there is good agreement between the source counts from existing Submillimetre Common User Bolometer Array (SCUBA; 850-µm) and Max Planck Millimetre Bolometer Array (MAMBO; 1.25-mm) surveys of different depths and areas, it remains difficult to determine the redshift distribution and bolometric luminosities of the submillimetre and millimetre galaxy population. This is principally due to the ambiguity in identifying an individual submillimetre source with its optical, IR or radio counterpart which, in turn, prevents a confident measurement of the spectroscopic redshift. Additionally, the lack of data measuring the rest-frame FIR spectral peak of the submillimetre galaxies gives rise to poor constraints on their rest-frame FIR luminosities and star formation rates. In this paper we describe Monte Carlo simulations of ground-based, balloon-borne and satellite submillimetre surveys that demonstrate how the restframe FIR‐submillimetre spectral energy distributions (250‐850 µm) can be used to derive photometric redshifts with an rms accuracy of ±0.4 over the range 0 3 × 10 12 L� ) with an accuracy of ∼20 per cent.

Dust emission and star formation toward a redshift 5.5 QSO

We report observations of the low-luminosity z =5 :50 quasar RD J030117+002025 (RD 0301 hereafter) at 250 GHz (1.20 mm) using the Max-Planck Millimeter Bolometer (MAMBO) array at the IRAM 30-meter telescope. The quasar was detected with a 1.2 mm flux density of 0:87 0:20 mJy. The lack of detectable 1.4 GHz radio emission indicates that the millimeter emission is of thermal nature, making RD 0301 the most distant dust- emission source known. When matching a 50 K grey body thermal far-infrared (FIR) spectrum to the observed millimeter flux we imply a FIR luminosity4 10 12 L, which is comparable to the quasar's optical luminosity. If the FIR luminosity arises from massive star formation, the implied star formation rate would be600M yr 1 , comparable to that of the starburst galaxies which dominate the average star formation and FIR emission in the early Universe. The FIR luminosity of RD 0301 is close to the average of that found in optically far more luminous high-redshift quasars. The comparably high millimeter to optical brightness ratio of RD 0301 is further evidence for that there is no strong correlation between the optical and millimeter brightness of high-redshift quasars, supporting the idea that in high-redshift quasars the dust is not heated by the AGN, but by starbursts.

A 1.2 mm MAMBO/IRAM-30 m survey of dust emission from the highest redshift PSS quasars

We report 250 GHz (1.2 mm) observations of redshift ≥ 3.8 quasars from the Palomar Sky Survey (PSS) sample, using the Max-Planck Millimetre Bolometer (MAMBO) array at the IRAM 30-metre telescope. Eighteen sources were detected and upper limits were obtained for 44 with 3σ flux density limits in the range 1.5-4 mJy. Adopting typical dust temperatures of 40-50 K, we derive dust masses of a few and far-infrared luminosities of order . We suggest that a substantial fraction of this luminosity arises from young stars, implying star formation rates approaching yr-1 or more. The high millimetre detection rate supports current views on a connection between AGN and star forming activity, suggesting a parallel evolution of the central black hole and of the stellar core of a galaxy, although their growth-rate ratio seems higher than the mass ratio observed in nearby galaxies. The observed, exceptionally bright objects may trace the peaks of the primordial density field, the cores of future giant ellipticals.