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Aims: The prime motivation of this project was to design and
build a state-of-art mm-wave heterodyne receiver system to enhance the
observing throughput of the IRAM 30-m radiotelescope. More specifically,
the requirements were i) state-of-art noise performance for
spectroscopic observations; ii) simultaneous dual polarization and
dual-frequency obs...
Context in source publication
Context 1
... SIS junctions are deposited to- gether with a superconducting circuit onto a quartz substrate. Figure 8 shows as an example the photograph of the Band 1 mixer chip. The superconducting circuit consists of different parts, each having a particular purpose: the waveguide probe on the left-hand side transforms the incoming radiation from waveguide mode to planar transmission line modes. ...
Citations
... We also used the The Eight MIxer Receiver (EMIR; [31]) band E090 was used as a front end, while the backend was the Versatile SPectrometer Array (VESPA), where the bandwidth was 18 × 20 MHz with a corresponding channel spacing of 20 kHz. The N 2 H + (1 − 0) and N 2 D + (1 − 0) lines were tuned at the frequencies of the strongest hyperfine component (J F 1 , F = 1 2, 3 − 0 1, 2 ) of the transition, which are 93, 173.7637 ...
Infrared dark clouds (IRDCs) are fruitful objects to study the fragmentation of interstellar filaments and initial conditions and early stages of high-mass (M>8 M⊙) star formation. We used the Yebes 40 m and Institut de Radioastronomie Millimétrique (IRAM) 30 m radio telescopes to carry out the first single-pointing spectral line observations towards the IRDC G1.75-0.08, which is a filamentary Central Molecular Zone (CMZ) cloud. Our aim is to reach an improved understanding of the gas kinematics and dynamical state of the cloud and its two clumps that we call clumps A and B. We also aim to determine the fractional abundances of the molecules detected at 3 mm towards G1.75-0.08. We detected HNCO(JKa,Kc=40,4−30,3), HCN(J=1−0), and HCO+(J=1−0) towards both clumps. The N2H+(J=1−0) line was detected only in clump B, while N2D+(J=1−0) was not detected at all. The HCN and HNCO spectra exhibit two velocity components. The abundances of the detected species are comparable to those in other IRDCs. An upper limit to the [N2D+]/[N2H+] deuterium fraction of <0.05 derived towards clump B is consistent with values observed in many high-mass clumps. The line mass analysis suggests that the G1.75-0.08 filament is subcritical by a factor of 11±6, and the clumps were found to be gravitationally unbound (αvir>2). Our finding that G1.75-0.08 is strongly subcritical is atypical compared to the general population of Galactic filamentary clouds. The cloud’s location in the CMZ might affect the cloud kinematics similar to what has been found for the Brick IRDC, and the cloud’s dynamical state might also be the result of the turbulent motions or shear and tidal forces in the CMZ. Because the target clumps are dark at 70 μm and massive (several 103 M⊙), they can be considered candidates for being high-mass starless clumps but not prestellar because they are not gravitationally bound.
... J.N., M.J.M., M.S. and A.L. acknowledge the support of the National Science Centre, Poland through the SONATA BIS grant 2018/30/E/ST9/00208. This research was funded in whole or in part by National Science Centre, Poland (grant number: 2021/41/N/ST9/02662 Facility: APEX (Güsten et al. 2006), IRAM-30m (Carter et al. 2012) Software: astropy (Astropy Collaboration et al. 2013, GILDAS (Pety 2005) ...
Star-forming galaxies populate a main sequence (MS), a well-defined relation between stellar mass (M*) and star-formation rate (SFR). Starburst (SB) galaxies lie significantly above the relation whereas quenched galaxies lie below the sequence. In order to study the evolution of galaxies on the SFR-M* plane and its connection to the gas content, we use the fact that recent episodes of star formation can be pinpointed by the existence of gamma-ray bursts (GRBs). Here we present sensitive [C I]-nondetections of z ∼ 2 ultra luminous infrared (ULIRG) GRB host galaxies. We find that our GRB hosts have similar molecular masses to those of other ULIRGs. However, unlike other ULIRGs, the GRB hosts are located at the MS or only a factor of a few above it. Hence, our GRB hosts are caught in the transition toward the SB phase. This is further supported by the estimated depletion times, which are similar to those of other transitioning galaxies. The GRB hosts are [C I]-dark galaxies, defined as having a [C I]/CO temperature brightness ratio of <0.1. Such a low [C I]/CO ratio has been found in high-density environments (n_H > 10^4 cm^−3) where CO is shielded from photodissociation, leading to under-abundances of [C I]. This is consistent with the merger process that is indeed suggested for our GRB hosts by their morphologies.
... All observations were taken under good weather conditions (0.08 <τ < 0.12; PWV < 2.5 mm). The absolute calibration accuracy for the EMIR receiver is around 10 per cent (Carter et al. 2012 ). The telescope intensity scale was converted into the main beam brightness temperature ( T mb ), using standard beam efficiency of ∼59 per cent at 230 GHz. ...
We have conducted the first extensive observational survey of several deuterated species in 16 Class 0/I proto-brown dwarfs (proto-BDs) and 4 Class Flat/Class II brown dwarfs. Observations were obtained with the IRAM 30m telescope in the DCO+ (3-2), DCN (3-2), DNC (3-2), and N2D+ (3-2) lines. The DCO+/H13CO+, DCN/H13CN, and DNC/HN13C ratios are comparatively higher and show a narrower range than the DCO+/HCO+, DCN/HCN, and DNC/HNC ratios, respectively. The mean D/H ratios for the proto-BDs derived from these molecules are in the range of ~0.02-3. Both low-temperature gas-phase ion-molecule deuteron transfer and grain surface reactions are required to explain the enhanced deuterium fractionation. The very dense and cold (nH2≥106 cm-3, T ≤10 K) interior of the proto-BDs provide the suitable conditions for efficient deuterium fractionation in these cores. There is no correlation between the D/H ratios and the CO depletion factor, with the exception of the DCN/HCN ratios that show a strong anti-correlation possibly due to the difference in the peak emitting regions of the DCN and HCN molecules. Over a wide range in the bolometric luminosities spanning ~0.002-40 L⊙, we find a trend of higher DCO+/HCO+ and DCN/HCN ratios, nearly constant DNC/HNC and DNC/HN13C ratios, and lower N2D+/N2H+ ratios in the proto-BDs compared to protostars. Only one Class II brown dwarf shows emission in the DCO+ (3-2) line. No correlation is seen between the D/H ratios and the evolutionary stage.
... A sub-sample of 110 targets were observed with the IRAM 30 m telescope in March 2016 (IRAM project code: 134-15) under varying weather conditions (1.3-3 mm precipitable water vapor). The EMIR receiver was used allowing these observations to cover the 86-93 GHz frequency range in one setup in dual polarization (Carter et al. 2012 position-switching mode with 10 mins per position. We used Herschel 250 µm data to identify clean off-positions located close to our target sources. ...
The evolutionary sequence for high-mass star formation starts with massive starless clumps that go on to form protostellar, young stellar objects and then compact HII regions. While there are many examples of the three later stages, the very early stages have proved to be elusive. We follow-up a sample of 110 mid-infrared dark clumps selected from the ATLASGAL catalogue with the IRAM telescope in an effort to identify a robust sample of massive starless clumps. We have used the HCO+ (1-0) and HNC (1-0) transitions to identify clumps associated with infall motion and the SiO (2-1) transition to identity outflow candidates. We have found blue asymmetric line profile in 65% of the sample, and have measured the infall velocities and mass infall rates (0.6-$36 \times 10^{-3}$ Msun/yr) for 33 of these clumps. We find a trend for the mass infall rate decreasing with an increase of bolometric luminosity to clump mass i.e. star formation within the clumps evolves. Using the SiO 2-1 line, we have identified good outflow candidates. Combining the infall and outflow tracers reveals that 67% of quiescent clumps are already undergoing gravitational collapse or are associated with star formation; these clumps provide us with our best opportunity to determined the initial conditions and study the earliest stages of massive star formation. Finally, we provide an overview of a systematic high-resolution ALMA study of quiescent clumps selected that allows us to develop a detailed understanding of earliest stages and their subsequent evolution.
... In the 2013 summer semester, we carried out the Institut de Radioastronomie Millimetrique (IRAM) 30-m observations under project number 030-13. We used the Eight MIxer Receiver (EMIR; Carter et al. 2012 ) at 3 mm to take fully sampled C 18 O (1-0) and 13 CO (1-0) maps simultaneously in a ∼108 arcmin 2 region towards NGC 2071-N. The on-the-fly mapping mode was used with position switching. ...
We present the first analysis in NGC2071-North as a resolved hub-filament featuring a double centre. This ∼1.5 × 1.5 parsec-scale filament hub contains ∼500 M⊙. Seen from Planck, magnetic field lines may have facilitated the gathering of material at this isolated location. The energy balance analysis, supported by infalling gas signatures, reveal that these filaments are currently forming stars. Herschel 100 μm emission concentrates in the hub, at IRAS 05451+0037 and LkHα 316, and presents diffuse lobes and loops around them. We suggest that such a double centre could be formed, because the converging locations of filament pairs are offset, by 2.3′ (0.27 pc). This distance also matches the diameter of a hub-ring, seen in column density and molecular tracers, such as HCO+ (1–0) and HCN (1–0), that may indicate a transition and the connection between the hub and the radiating filaments. We argue that all of the three components of the emission star LkHα 316 are in physical association. We find that a ∼0.06 pc-sized gas loop, attached to IRAS 05451+0037, can be seen at wavelengths all the way from Pan-STARRS-i to Herschel-100 μm. These observations suggest that both protostars at the double hub centre are interacting with the cloud material. In our 13CO data, we do not seem to find the outflow of this region that was identified in the 80s with much lower resolution.
... Recent work with that telescope includes the study of star formation physics in nearby galaxies [16], and investigations of molecular cloud structure and evolution in the Milky Way that support the aforementioned extragalactic work [17,18]. Many of these studies employ the EMIR receiver system that samples 16 GHz of bandwidth per polarization in the 70-115 GHz range [19]. Installation of receiver and backend systems matching or exceeding this capability would open up new and exciting capabilities for the US-based community. ...
The Haystack Telescope is an antenna with a diameter of 37~m and an elevation-dependent surface accuracy of $\le{}100~\mu{}\rm{}m$ that is capable of millimeter-wave observations. The radome-enclosed instrument serves as a radar sensor for space situational awareness, with about one-third of the time available for research by MIT Haystack Observatory. Ongoing testing with the K-band (18-26~GHz) and W-band receivers (currently 85-93~GHz) is preparing the inclusion of the telescope into the Event Horizon Telescope (EHT) array and the use as a single-dish research telescope. Given its geographic location, the addition of the Haystack Telescope to current and future versions of the EHT array would substantially improve the image quality.
... Recent work with that telescope includes the study of star formation physics in nearby galaxies [16], and investigations of molecular cloud structure and evolution in the Milky Way that support the aforementioned extragalactic work [17,18]. Many of these studies employ the EMIR receiver system that samples 16 GHz of bandwidth per polarization in the 70-115 GHz range [19]. Installation of receiver and backend systems matching or exceeding this capability would open up new and exciting capabilities for the US-based community. ...
The Haystack Telescope is an antenna with a diameter of 37 m and an elevation-dependent surface accuracy of ≤100μm that is capable of millimeter-wave observations. The radome-enclosed instrument serves as a radar sensor for space situational awareness, with about one-third of the time available for research by MIT Haystack Observatory. Ongoing testing with the K-band (18–26 GHz) and W-band receivers (currently 85–93 GHz) is preparing the inclusion of the telescope into the Event Horizon Telescope (EHT) array and the use as a single-dish research telescope. Given its geographic location, the addition of the Haystack Telescope to current and future versions of the EHT array would substantially improve the image quality.
... In the 2013 summer semester we carried out IRAM 30 m observations under project number 030-13. We used the EMIR receiver (Carter et al. 2012) at 3 mm to take fully-sampled C 18 O(1-0) and 13 CO(1-0) maps simultaneously in a ∼ 108 arcmin 2 region toward NGC2071-N. The on-the-fly mapping mode was used with position-switching. ...
We present the first analysis in NGC2071-North as a resolved hub-filament featuring a double centre. This $\sim 1.5 \times 1.5$ parsec-scale filament hub contains $\sim$500 $M_\odot$. Seen from Planck, magnetic field lines may have facilitated the gathering of material at this isolated location. The energy balance analysis, supported by infalling gas signatures, reveal that these filaments are currently forming stars. Herschel 100 $\mu$m emission concentrates in the hub, at IRAS 05451+0037 and LkH$\alpha$ 316, and presents diffuse lobes and loops around them. We suggest that such a double centre could be formed, because the converging locations of filament pairs are offset, by 2.3$'$ (0.27 pc). This distance also matches the diameter of a hub-ring, seen in column density and molecular tracers, such as HCO$^+$(1$-$0) and HCN(1$-$0), that may indicate a transition and the connection between the hub and the radiating filaments. We argue that all of the three components of the emission star LkH$\alpha$ 316 are in physical association. We find that a $\sim$0.06 pc-sized gas loop, attached to IRAS 05451+0037, can be seen at wavelengths all the way from Pan-STARRS-i to Herschel-100 $\mu$m. These observations suggest that both protostars at the double hub centre are interacting with the cloud material. In our $^{13}$CO data, we do not seem to find the outflow of this region that was identified in the 80s with much lower resolution.
... ULTI-BAND receiving systems have gained significant popularity as a solution for instrumentation in environmental sciences and radio astronomy [1]. In such systems, the receiver channels run simultaneously while the receivers' spatial pointing is aligned. ...
In this work, we report on the design and characterization of an all-metal, wideband single-layer dichroic filter operating at non-normal beam incidence. The dichroic filter consists of a perforated metal plate with an angular offset of the perforated channels equal to the beam incidence angle onto the dichroic surface. The fabricated filter is characterized using an especially designed quasi-optical test system. The filter demonstrates 96% transmission of the incoming electromagnetic radiation averaged in the signal band about 37-50 GHz for both polarizations while simultaneously achieving a rejection better than 20 dB for frequencies lower than 26 GHz at the designed beam incidence of 13 degrees. The cross-polarization level for each polarization is better than 30 dB in the passband. The experimental results of the transmission measurements are in very good agreement with electromagnetic simulations confirming the feasibility and benefits of our proposed design concept even at THz frequencies. The simulations of the dichroic scaled version demonstrate that, for instance, it can be employed in the Event Horizon Telescope project, where the 230 GHz and the 345 GHz receiver channels could be operating simultaneously.
... POLAMI is a long term monitoring program conducted at the IRAM 30 m telescope that observes simultaneously the total flux, the linear and circular polarization of a set of some of the brightest millimeter AGN at 86 (3.5 mm) and 229 GHz (1.3 mm); see [22] for the source list and calibrators observed. Observations are mainly made with the Observatory's EMIR receiver [25] and the XPOL 4-Stokes polarimetric procedures [26]. The program started in autumn 2006 and is expected to be active until at least the summer of 2024. ...
We review results from the POLAMI program, which monitors the polarization properties of 36 blazars at the IRAM 30 m telescope. We found that the variability of the degree of linear polarization is faster and of higher amplitude at 1 mm than at 3 mm and that the linear polarization is also more variable than the total flux. The linear polarization angle is highly variable in all sources with excursions > 180°; and for the case of the polarization angle, also the 1 mm variations appear to be faster than those at 3 mm. These results are fully compatible with recent multi-zone turbulent jet models, and they definitively rule out the popular single-zone models for blazars. They also further confirm that the short-wavelength (inner) emitting regions have better ordered magnetic fields than the long-wavelength ones (further downstream). Moreover, the POLAMI program has shown statistical evidence that, for most of the monitored sources, circular polarization emission is displayed the majority of the time. The circular polarization detection rate and the maximum degree of circular polarization found are comparable with previous surveys at much longer wavelengths, thus, opening a new window for circular polarization and jet composition studies in the mm range. The process generating circular polarization must not be strongly wavelength-dependent. The widespread presence of circular polarization in the POLAMI sample is likely due to Faraday conversion of the linearly polarized synchrotron radiation in the helical magnetic field of the jets. The peculiar behavior of circular polarization in 3C 66A, which we consider a hallmark of circular polarization generation by Faraday conversion in helical fields, is discussed.
