Discovery of a Highly Collimated Flow from the High-mass Protostar ISOSS J23053+5953 SMM2

Abstract We present Very Large Array C-, X-, and Q-band continuum observations, as well as 1.3 mm continuum and CO(2-1) observations with the Submillimeter Array toward the high-mass protostellar candidate ISOSS J23053+5953 SMM2. Compact centimeter continuum emission was detected near the center of the SMM2 core with a spectral index of 0.24(± 0.15) between 6 and 3.6 cm, and a radio luminosity of 1.3(±0.4) mJy kpc2. The 1.3 mm thermal dust emission indicates a mass of the SMM2 core of 45.8 (±13.4) M ⊙, and a density of 7.1 (±1.2)× 106 cm−3. The CO(2-1) observations reveal a large, massive molecular outflow centered on the SMM2 core. This fast outflow (>50 km s−1 from the cloud systemic velocity) is highly collimated, with a broader, lower-velocity component. The large values for outflow mass (45.2 ± 12.6 M ⊙) and momentum rate (6 ± 2 × 10−3 M ⊙ km s−1yr−1) derived from the CO emission are consistent with those of flows driven by high-mass YSOs. The dynamical timescale of the flow is between 1.5 and 7.2 × 104 yr. We also found from the C18O to thermal dust emission ratio that CO is depleted by a factor of about 20, possibly due to freeze-out of CO molecules on dust grains. Our data are consistent with previous findings that ISOSS J23053 + 5953 SMM2 is an emerging high-mass protostar in an early phase of evolution, with an ionized jet and a fast, highly collimated, and massive outflow.

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Massive Molecular Outflow and 100 kpc Extended Cold Halo Gas in the Enormous Lyα Nebula of QSO 1228+3128

The Astrophysical Journal ◽

10.3847/2041-8213/ac390d ◽

2021 ◽

Vol 922 (2) ◽

pp. L29

Author(s):

Jianrui Li ◽

Bjorn H. C. Emonts ◽

Zheng Cai ◽

J. Xavier Prochaska ◽

Ilsang Yoon ◽

...

Keyword(s):

Radio Source ◽

Bulk Velocity ◽

Molecular Gas ◽

Gas Reservoir ◽

Massive Galaxies ◽

Gas Phases ◽

Molecular Outflow ◽

Halo Gas ◽

Massive Outflow ◽

Co Emission

Abstract The link between the circumgalactic medium (CGM) and the stellar growth of massive galaxies at high-z depends on the properties of the widespread cold molecular gas. As part of the SUPERCOLD-CGM survey (Survey of Protocluster ELANe Revealing CO/[C i] in the Lyα-Detected CGM), we present the radio-loud QSO Q1228+3128 at z = 2.2218, which is embedded in an enormous Lyα nebula. ALMA+ACA observations of CO(4–3) reveal both a massive molecular outflow, and a more extended molecular gas reservoir across ∼100 kpc in the CGM, each containing a mass of M H2 ∼ 4–5 × 1010 M ⊙. The outflow and molecular CGM are aligned spatially, along the direction of an inner radio jet. After reanalysis of Lyα data of Q1228+3128 from the Keck Cosmic Web Imager, we found that the velocity of the extended CO agrees with the redshift derived from the Lyα nebula and the bulk velocity of the massive outflow. We propose a scenario where the radio source in Q1228+3128 is driving the molecular outflow and perhaps also enriching or cooling the CGM. In addition, we found that the extended CO emission is nearly perpendicular to the extended Lyα nebula spatially, indicating that the two gas phases are not well mixed, and possibly even represent different phenomena (e.g., outflow versus infall). Our results provide crucial evidence in support of predicted baryonic recycling processes that drive the early evolution of massive galaxies.

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Quasi-simultaneous Radio/X-Ray Observations of the Candidate Transitional Millisecond Pulsar 3FGL J1544.6−1125 during its Low-luminosity Accretion-disk State

The Astrophysical Journal ◽

10.3847/1538-4357/ac1ff7 ◽

2021 ◽

Vol 923 (1) ◽

pp. 3

Author(s):

Amruta D. Jaodand ◽

Adam T. Deller ◽

Nina Gusinskaia ◽

Jason W. T. Hessels ◽

James C. A. Miller-Jones ◽

...

Keyword(s):

Accretion Disk ◽

Radio Continuum ◽

Continuum Emission ◽

Large Array ◽

Millisecond Pulsar ◽

Very Large Array ◽

X Ray ◽

Upper Limit ◽

5 Ghz ◽

Variable Radio

Abstract 3FGL J1544.6−1125 is a candidate transitional millisecond pulsar (tMSP). Similar to the well-established tMSPs—PSR J1023+0038, IGR J18245−2452, and XSS J12270−4859—3FGL J1544.6−1125 shows γ-ray emission and discrete X-ray “low” and “high” modes during its low-luminosity accretion-disk state. Coordinated radio/X-ray observations of PSR J1023+0038 in its current low-luminosity accretion-disk state showed rapidly variable radio continuum emission—possibly originating from a compact, self-absorbed jet, the “propellering” of accretion material, and/or pulsar moding. 3FGL J1544.6−1125 is currently the only other (candidate) tMSP system in this state, and can be studied to see whether tMSPs are typically radio-loud compared to other neutron star binaries. In this work, we present a quasi-simultaneous Very Large Array and Swift radio/X-ray campaign on 3FGL J1544.6−1125. We detect 10 GHz radio emission varying in flux density from 47.7 ± 6.0 μJy down to ≲15 μJy (3σ upper limit) at four epochs spanning three weeks. At the brightest epoch, the radio luminosity is L 5 GHz = (2.17 ± 0.17) × 1027 erg s−1 for a quasi-simultaneous X-ray luminosity L 2–10 keV = (4.32 ± 0.23) × 1033 erg s−1 (for an assumed distance of 3.8 kpc). These luminosities are close to those of PSR J1023+0038, and the results strengthen the case that 3FGL J1544.6−1125 is a tMSP showing similar phenomenology to PSR J1023+0038.

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Observations of H2O maser and continuum emission in AFGL 2591

Symposium - International Astronomical Union ◽

10.1017/s0074180900222080 ◽

2002 ◽

Vol 206 ◽

pp. 68-71

Author(s):

Miguel A. Trinidad ◽

Salvador Curiel ◽

Jorge Cantó ◽

José M. Torrelles ◽

Luis F. Rodríguez ◽

...

Keyword(s):

Radio Continuum ◽

Continuum Emission ◽

Molecular Flow ◽

Large Array ◽

Very Large Array ◽

Star Forming ◽

Bipolar Outflow ◽

Maser Line ◽

H Ii Region

We report results of radio continuum (1.3 and 3.6 cm) and H2O maser line observations, made with the Very Large Array (A configuration), toward the star-forming region AFGL 2591. We detected 85 maser spots toward this region, which are distributed in three main groups. Two of these groups spatially coincide with the radio continuum sources VLA 2 and VLA 3. The maser spots associated with VLA 3 are distributed along a shell-like structure of 0.01 and nearly perpendicular to the CO bipolar outflow. We propose that VLA 3 is the center of the observed molecular flow in this region. Finally, we confirm that AFGL 2591 region is a cluster of B type stars, each one with its own optically thin H II region.

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A Face-on Accretion System in High Mass Star-Formation: Possible Dusty Infall Streams within 100 Astronomical Unit

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317010973 ◽

2017 ◽

Vol 13 (S336) ◽

pp. 267-270

Author(s):

Kazuhito Motogi ◽

Tomoya Hirota ◽

Kazuo Sorai ◽

Yoshinori Yonekura ◽

Koichiro Sugiyama ◽

...

Keyword(s):

Equatorial Plane ◽

Dust Emission ◽

High Mass ◽

Mass Star ◽

Astronomical Unit ◽

Very Large Array ◽

The Face ◽

Open Question ◽

Long Baselines ◽

The Continuum

AbstractWe report on interferometric observations of a face-on accretion system around the high mass young stellar object, G353.273+0.641. The innermost accretion system of 100-au radius was resolved in a 45-GHz continuum image taken with the Jansky Very Large Array. Our SED analysis indicated that the continuum could be explained by optically-thick dust emission. 6.7 GHz CH3OH masers associated with the same system were also observed with the Australia Telescope Compact Array. The masers showed a spiral-like, non-axisymmetric distribution with a systematic velocity gradient. The line-of-sight velocity field is explained by an infall motion along a parabolic streamline that falls onto the equatorial plane of the face-on system. The streamline is quasi-radial and reaches the equatorial plane at a radius of 16 au. The physical origin of such a streamline is still an open question and will be constrained by the higher-resolution thermal continuum and line observations with ALMA long baselines.

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VLA cm-wave survey of young stellar objects in the Oph A cluster: constraining extreme UV- and X-ray-driven disk photoevaporation

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935340 ◽

2019 ◽

Vol 631 ◽

pp. A58 ◽

Cited By ~ 1

Author(s):

A. Coutens ◽

H. B. Liu ◽

I. Jiménez-Serra ◽

T. L. Bourke ◽

J. Forbrich ◽

...

Keyword(s):

Dust Emission ◽

Class Ii ◽

Field Of View ◽

Young Stellar Objects ◽

Continuum Emission ◽

Class Iii ◽

Stellar Objects ◽

Very Large Array ◽

X Ray ◽

Extreme Uv

Observations of young stellar objects (YSOs) in centimeter bands can probe the continuum emission from growing dust grains, ionized winds, and magnetospheric activity that are intimately connected to the evolution of protoplanetary disks and the formation of planets. We carried out sensitive continuum observations toward the Ophiuchus A star-forming region, using the Karl G. Jansky Very Large Array (VLA) at 10 GHz over a field-of-view of 6′ and with a spatial resolution of θmaj ×θmin ~ 0.′′4 × 0.′′2. We achieved a 5 μJy beam−1 rms noise level at the center of our mosaic field of view. Among the 18 sources we detected, 16 were YSOs (three Class 0, five Class I, six Class II, and two Class III) and two were extragalactic candidates. We find that thermal dust emission generally contributed less than 30% of the emission at 10 GHz. The radio emission is dominated by other types of emission, such as gyro-synchrotron radiation from active magnetospheres, free–free emission from thermal jets, free–free emission from the outflowing photoevaporated disk material, and synchrotron emission from accelerated cosmic-rays in jet or protostellar surface shocks. These different types of emission could not be clearly disentangled. Our non-detections for Class II/III disks suggest that extreme UV-driven photoevaporation is insufficient to explain disk dispersal, assuming that the contribution of UV photoevaporating stellar winds to radio flux does not evolve over time. The sensitivity of our data cannot exclude photoevaporation due to the role of X-ray photons as an efficient mechanism for disk dispersal. Deeper surveys using the Square Kilometre Array (SKA) will have the capacity to provide significant constraints to disk photoevaporation.

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The diagnostic power of radio spectra from star-forming galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319002898 ◽

2019 ◽

Vol 15 (S341) ◽

pp. 177-186

Author(s):

Eric J. Murphy

Keyword(s):

Star Formation ◽

Dust Emission ◽

Cosmic Ray ◽

Microwave Emission ◽

Radio Continuum ◽

Continuum Emission ◽

H Ii Regions ◽

Synchrotron Emission ◽

Very Large Array ◽

Star Forming

AbstractRadio continuum emission from galaxies is powered by a combination of distinct physical processes, each providing unique diagnostic information. Over frequencies spanning ∼ 1–120 GHz, radio spectra of star-forming galaxies are primarily comprised of: (1) non-thermal synchrotron emission powered by accelerated cosmic-ray electrons/positrons; (2) free-free emission from young massive star-forming (H ii) regions; (3) anomalous microwave emission, which is a dominant, but completely unconstrained, foreground in cosmic microwave background experiments; and (4) cold, thermal dust emission that accounts for most of the dust and total mass content in the interstellar medium in galaxies. In this proceeding, we discuss these key energetic processes that contribute to the radio emission from star-forming galaxies, with an emphasis on frequencies ≳30 GHz, where current investigations of star formation within nearby galaxies show that the free-free emission begins to dominate over non-thermal synchrotron emission. We also discuss how planned radio facilities that will access these frequencies, such as a next-generation Very Large Array (ngVLA), will be transformative to our understanding of the star formation process in galaxies.

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The CO Luminosity Density at High-z (COLDz) Survey: A Sensitive, Large-area Blind Search for Low-J CO Emission from Cold Gas in the Early Universe with the Karl G. Jansky Very Large Array

The Astrophysical Journal ◽

10.3847/1538-4357/aacb79 ◽

2018 ◽

Vol 864 (1) ◽

pp. 49 ◽

Cited By ~ 35

Author(s):

Riccardo Pavesi ◽

Chelsea E. Sharon ◽

Dominik A. Riechers ◽

Jacqueline A. Hodge ◽

Roberto Decarli ◽

...

Keyword(s):

Early Universe ◽

Large Array ◽

Large Area ◽

Very Large Array ◽

Blind Search ◽

Co Emission ◽

Cold Gas

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A variability study of the H2CO 6cm maser in IRAS 18566+0408

Proceedings of the International Astronomical Union ◽

10.1017/s1743921307012707 ◽

2007 ◽

Vol 3 (S242) ◽

pp. 140-141

Author(s):

E. Araya ◽

P. Hofner ◽

S. Kurtz ◽

H. Linz ◽

M. Sewilo ◽

...

Keyword(s):

Short Duration ◽

Line Profile ◽

Stellar Object ◽

Circumstellar Disk ◽

Large Array ◽

Very Large Array ◽

Green Bank Telescope ◽

Variability Study ◽

Co Emission

AbstractWe report the first detection of a short-duration (<3 months) outburst of an H2CO 6cm maser based on multi-epoch observations of IRAS18566+0408 obtained with Arecibo, the Green Bank Telescope, and the Very Large Array. The H2CO maser was observed nine times between 2002 and 2005. In May 2006 we began a two-year program of monthly monitoring with the Arecibo Telescope. The H2CO maser in IRAS18566+0408 is coincident with a young massive stellar object and the line profile of the maser suggests that the H2CO emission originates from two different regions, perhaps associated with the kinematics of a circumstellar disk.

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A 10-M⊙ YSO with a Keplerian disk and a nonthermal radio jet

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834366 ◽

2019 ◽

Vol 622 ◽

pp. A206 ◽

Cited By ~ 7

Author(s):

L. Moscadelli ◽

A. Sanna ◽

R. Cesaroni ◽

V. M. Rivilla ◽

C. Goddi ◽

...

Keyword(s):

Dust Emission ◽

Major Axis ◽

High Mass ◽

Continuum Emission ◽

High Angular Resolution ◽

Central Mass ◽

Disk Radius ◽

Dynamical Interaction ◽

Linear Pattern ◽

Nonthermal Radio

Context. To constrain present star formation models, we need to simultaneously establish the dynamical and physical properties of disks and jets around young stars. Aims. We previously observed the star-forming region G16.59−0.05 through interferometric observations of both thermal and maser lines, and identified a high-mass young stellar object (YSO) which is surrounded by an accretion disk and drives a nonthermal radio jet. Our goals are to establish the physical conditions of the environment hosting the high-mass YSO and to study the kinematics of the surrounding gas in detail. Methods. We performed high-angular-resolution (beam FWHM ≈ 0′′.15) 1.2-mm continuum and line observations towards G16.59−0.05 with the Atacama Large Millimeter Array (ALMA). Results. The main dust clump, with size ≈104 au, is resolved into four distinct, relatively compact (diameter ~2000 au) millimeter (mm) sources. The source harboring the high-mass YSO is the most prominent in molecular emission. By fitting the emission profiles of several unblended and optically thin transitions of CH3OCH3 and CH3OH, we derived gas temperatures inside the mm sources in the range 42–131 K, and calculated masses of 1–5 M⊙. A well-defined Local Standard of Rest (LSR) velocity (VLSR) gradient is detected in most of the high-density molecular tracers at the position of the high-mass YSO, pinpointed by compact 22-GHz free-free emission. This gradient is oriented along a direction forming a large (≈70°) angle with the radio jet, traced by elongated 13-GHz continuum emission. The butterfly-like shapes of the P–V plots and the linear pattern of the emission peaks of the molecular lines at high velocity confirm that this VLSR gradient is due to rotation of the gas in the disk surrounding the high-mass YSO. The disk radius is ≈500 au, and the VLSR distribution along the major axis of the disk is well reproduced by a Keplerian profile around a central mass of 10 ± 2 M⊙. The position of the YSO is offset by ≳0′′.1 from the axis of the radio jet and the dust emission peak. To explain this displacement we argue that the high-mass YSO could have moved from the center of the parental mm source owing to dynamical interaction with one or more companions.

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