scholarly journals Radio emission from young stellar objects in the Rho Ophiuchi cloud

1987 ◽  
Vol 122 ◽  
pp. 61-62
Author(s):  
Ph. André ◽  
T. Montmerle ◽  
E.D. Feigelson ◽  
P. Stine
Keyword(s):  
Radio Emission ◽  
Radio Continuum ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
X Ray ◽  
Rho Ophiuchi ◽  
5 Ghz ◽  
Radio Stars ◽  
Shed Light

Following an Einstein X-ray survey of the rho Oph molecular cloud, uncovering several dozen young stellar objects (YSO) (Montmerle et al. 1983), an extensive radio continuum VLA(C) survey was conducted in 1983 to look for counterparts to these sources at 1.4 and 5 GHz (André et al. 1986) To shed light on emission mechanisms, we performed follow-up VLA(A/B) observations of identified radio stars in March 1985 at 1.4, 5 and 15 GHz.

scholarly journals The RMS survey: radio observations of candidate massive YSOs in the southern hemisphere

2006 ◽  
Vol 2 (S237) ◽  
pp. 482-482 ◽  
Author(s):  
J. S. Urquhart ◽  
A. L. Busfield ◽  
M. G. Hoare ◽  
S. L. Lumsden ◽  
A. J. Clarke ◽  
...  
Keyword(s):  
Hii Regions ◽  
Point Sources ◽  
Radio Continuum ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
Evolved Stars ◽  
Multi Wavelength ◽  
Sources Of Contamination ◽  
Compact Array

AbstractThe Red MSX Source (RMS) survey (Hoare et al. 2005) is a multi-wavelength programme of follow-up observations designed to distinguish between genuine massive young stellar objects (MYSOs) and other embedded or dusty objects, such as ultra compact (UC) HII regions, evolved stars and planetary nebulae (PNe). We have identified nearly 2000 MYSOs candidates by comparing the colours of MSX and 2MASS point sources to those of known MYSOs. There are several other types of embedded or dust enshrouded objects that have similar colours as MYSOs and contaminate our sample. Two sources of contamination are from UCHII regions and PNe, both of which can be identified from the radio emission emitted by their ionised nebulae. In order to identify UCHII regions and PNe that contaminate our sample we have conducted high resolution radio continuum observations at 3.6 and 6 cm of all southern MYSOs candidates (235° < l < 350°) using the Australia Telescope Compact Array (ATCA).

scholarly journals A Systematic Study of X-Ray Flares from Low-Mass Young Stellar Objects in the $\rho$ Ophiuchi Star-Forming Region with Chandra

2003 ◽  
Vol 55 (3) ◽  
pp. 653-681 ◽  
Author(s):  
Kensuke Imanishi ◽  
Hiroshi Nakajima ◽  
Masahiro Tsujimoto ◽  
Katsuji Koyama ◽  
Yohko Tsuboi
Keyword(s):  
Systematic Study ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
X Ray ◽  
Star Forming ◽  
Low Mass ◽  
Rho Ophiuchi

Radio Emission from Young Stellar Objects in the Rho Ophiuchi Cloud

1987 ◽  
pp. 61-62 ◽  
Author(s):  
Ph. André ◽  
T. Montmerle ◽  
E. D. Feigelson ◽  
P. Stine
Keyword(s):  
Radio Emission ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
Rho Ophiuchi

scholarly journals A Novel Method for Estimating the Ambient Medium Density Around Distant Radio Sources from Their Observed Radio Spectra

2021 ◽  
Vol 922 (2) ◽  
pp. 197
Author(s):  
Anna Wójtowicz ◽  
Łukasz Stawarz ◽  
Jerzy Machalski ◽  
Luisa Ostorero
Keyword(s):  
Radio Emission ◽  
Ambient Medium ◽  
Radio Galaxies ◽  
Radiative Properties ◽  
Radio Continuum ◽  
Physical Parameters ◽  
Radio Sources ◽  
Data Set ◽  
Radio Structure ◽  
5 Ghz

Abstract The dynamical evolution and radiative properties of luminous radio galaxies and quasars of the FR II type, are well understood. As a result, through the use of detailed modeling of the observed radio emission of such sources, one can estimate various physical parameters of the systems, including the density of the ambient medium into which the radio structure evolves. This, however, requires rather comprehensive observational information, i.e., sampling the broadband radio continua of the targets at several frequencies, and imaging their radio structures with high resolution. Such observations are, on the other hand, not always available, especially for high-redshift objects. Here, we analyze the best-fit values of the source physical parameters, derived from extensive modeling of the largest currently available sample of FR II radio sources, for which good-quality multiwavelength radio flux measurements could be collected. In the analyzed data set, we notice a significant and nonobvious correlation between the spectral index of the nonthermal radio emission continuum, and density of the ambient medium. We derive the corresponding correlation parameters, and quantify the intrinsic scatter by means of Bayesian analysis. We propose that the discovered correlation could be used as a cosmological tool to estimate the density of ambient medium for large samples of distant radio galaxies. Our method does not require any detailed modeling of individual sources, and relies on limited observational information, namely, the slope of the radio continuum between the rest-frame frequencies 0.4 and 5 GHz, possibly combined with the total linear size of the radio structure.

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

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.

scholarly journals A Theoretical Model of X-Ray Jets from Young Stellar Objects

2017 ◽  
Vol 847 (1) ◽  
pp. 46 ◽  
Author(s):  
Shinsuke Takasao ◽  
Takeru K. Suzuki ◽  
Kazunari Shibata
Keyword(s):  
Theoretical Model ◽  
Young Stellar Objects ◽  
Stellar Objects ◽  
X Ray

scholarly journals Hard-X-ray-selected active galactic nuclei – I. A radio view at high frequencies

2020 ◽  
Vol 495 (4) ◽  
pp. 3943-3960 ◽  
Author(s):  
E Chiaraluce ◽  
F Panessa ◽  
G Bruni ◽  
R D Baldi ◽  
E Behar ◽  
...  
Keyword(s):  
Radio Emission ◽  
Active Galactic Nuclei ◽  
High Frequency ◽  
Galactic Nuclei ◽  
High Frequencies ◽  
X Ray ◽  
Physical Mechanisms ◽  
Nuclear Contribution ◽  
Hot Corona ◽  
Shed Light

ABSTRACT A thorough study of radio emission in active galactic nuclei (AGNs) is of fundamental importance to understand the physical mechanisms responsible for the emission and the interplay between accretion and ejection processes. High-frequency radio observations can target the nuclear contribution of smaller emitting regions and are less affected by absorption. We present JVLA 22 and 45 GHz observations of 16 nearby (0.003 ≤ z ≤ 0.3) hard-X-ray-selected AGNs at the (sub)-kpc scale with tens μJy beam−1 sensitivity. We detected 15/16 sources, with flux densities ranging from hundreds μJy to tens Jy (specific luminosities from ∼1020 to ${\sim}10^{25}\, \mathrm{ W}\, \mathrm{ Hz}^{-1}$ at 22 GHz). All detected sources host a compact core, with eight being core-dominated at either frequencies, the others exhibiting also extended structures. Spectral indices range from steep to flat/inverted. We interpret this evidence as either due to a core+jet system (6/15), a core accompanied by surrounding star formation (1/15), to a jet oriented close to the line of sight (3/15), to emission from a corona or the base of a jet (1/15), although there might be degeneracies between different processes. Four sources require more data to shed light on their nature. We conclude that, at these frequencies, extended, optically thin components are present together with the flat-spectrum core. The LR/LX ∼ 10−5 relation is roughly followed, indicating a possible contribution to radio emission from a hot corona. A weakly significant correlation between radio core (22 and 45 GHz) and X-ray luminosities is discussed in the light of an accretion–ejection framework.

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