Near-Infrared Coronagraphic Observations of a Classical T Tauri Star, DO Taurus

Itoh, Yoichi; Hayashi, Masahiko; Tamura, Motohide; Oasa, Yumiko; Hioki, Tomonori; Fukagawa, Misato; Kudo, Tomoyuki

doi:10.1093/pasj/60.2.223

Cited by 13 publications

(31 citation statements)

References 24 publications

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“…Indeed, the nearby Scd galaxy, NGC 4945, hosting a low-mass SMBH (M BH ≈ 1.4 × 10 6 M ; Greenhill, Moran & Herrnstein 1997) only displays evidence for AGN activity in Xray (Iwasawa et al 1993) and mid-infrared (mid-IR) observations (Goulding & Alexander 2009). By contrast, the AGN in NGC 4945 (accreting at > ≈ 30 per cent of the predicted Eddington limit; Itoh et al 2008) is completely hidden at optical wavelengths, and classified as a starburst galaxy. Clearly, using optical data alone, the intrinsic AGN properties of sources similar to NGC 4945 cannot be derived.…”

Section: Introductionmentioning

confidence: 89%

“…Here we conservatively adopt the Compton-thin L X value of Guainazzi et al (2004); however, we note that if we use the value of Maiolino et al (1998), then NGC 5643 would lie on our derived relationship. NGC 4945, by contrast, has observations using Ginga, ASCA, OSSE, the Rossi X-ray Timing Explorer, BeppoSAX, Suzaku and most recently Swift-BAT (Iwasawa et al 1993;Tanaka, Inoue & Holt 1994;Done, Madejski & Smith 1996;Madejski et al 2000;Guainazzi et al 2000;Itoh et al 2008;Tueller et al 2008, respectively) all of which provide excellent and consistent spectral constraints over a wide X-ray band (1-200 keV) showing that the central source is Compton thick (N H ≈ 4 × 10 24 cm −2 ), with L X,2−10 keV ≈ (3-10) × 10 42 erg s −1 and an observed intrinsic variability of a factor of ≈2. Here we adopt the luminosity from the most recent observation by Swift, L X ≈ 3 × 10 42 erg s −1 .…”

Section: [O Iv] Luminosity As a Tracer Of The Bolometric Luminosity Omentioning

confidence: 99%

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Towards a complete census of active galactic nuclei in nearby galaxies: the incidence of growing black holes

Goulding

Alexander

Lehmer

et al. 2010

Monthly Notices of the Royal Astronomical Society

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We investigate the local supermassive black hole (SMBH) density function and relative mass accretion rates of all active galactic nuclei (AGNs) identified in a volume‐limited sample of infrared (IR) bright galaxies (LIR > 3 × 109 L⊙) to D < 15 Mpc. A data base of accurate SMBH mass (MBH) estimates is compiled from literature sources using physically motivated AGN modelling techniques (reverberation mapping, maser mapping and gas kinematics) and well‐established indirect MBH estimation methods (the M–σ* and MBH–LK,bul relations). For the three sources without previously published MBH estimates, we use Two Micron All Sky Survey (2MASS) K‐band imaging and galfit to constrain the bulge luminosities, and hence SMBH masses. In general, we find the AGNs in the sample host SMBHs which are spread over a wide mass range [MBH≈ (0.1–30) × 107 M⊙], but with the majority in the poorly studied MBH≈ 106–107 M⊙ region. Using sensitive hard X‐ray (2–10 keV) and mid‐IR constraints we calculate the bolometric luminosities of the AGNs (LBol,AGN) and use them to estimate relative mass accretion rates. We use these data to calculate the volume‐averaged SMBH growth rate of galaxies in the local Universe and find that the AGNs hosting SMBHs in the mass range MBH≈ 106–107 M⊙ are dominated by optically unidentified AGNs. These relatively small SMBHs are acquiring a significant proportion of their mass in the present day, and are amongst the most rapidly growing in the local Universe (SMBH mass‐doubling times of ≈6 Gyr). Additionally, we find tentative evidence for an increasing volume‐weighted AGN fraction with decreasing SMBH mass in the MBH≈ 106–108 M⊙ range. Overall, we conclude that significant mass accretion on to small SMBHs may be missed in even the most sensitive optical surveys due to absent or weak optical AGN signatures.

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Section: Introductionmentioning

confidence: 89%

Section: [O Iv] Luminosity As a Tracer Of The Bolometric Luminosity Omentioning

confidence: 99%

Towards a complete census of active galactic nuclei in nearby galaxies: the incidence of growing black holes

Goulding

Alexander

Lehmer

et al. 2010

Monthly Notices of the Royal Astronomical Society

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“…Koerner & Sargent (1995) detected CO emission, but with a very broad blueshifted wing, which probably traces an outflow, and may indicate that this source is quite young. Indeed, it is surrounded by an optical nebulosity along a redshifted optical jet (see Itoh et al 2008, possible ∼5σ detection, but the derived velocity, ∼4.3 km s −1 , does not agree with the better determination from HCO + or CN, so we consider this as noise.…”

Section: Do Taumentioning

confidence: 97%

Chemistry in disks

Guilloteau

Reboussin

Dutrey

et al. 2016

A&A

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Aims. We attempt to determine the molecular composition of disks around young low-mass stars. Methods. We used the IRAM 30 m radio telescope to perform a sensitive wideband survey of 30 stars in the Taurus Auriga region known to be surrounded by gaseous circumstellar disks. We simultaneously observed HCO + (3−2), HCN(3−2), C 2 H(3−2), CS(5−4), and two transitions of SO. We combined the results with a previous survey that observed 13 CO (2−1), CN(2−1), two o-H 2 CO lines, and another transition of SO. We used available interferometric data to derive excitation temperatures of CN and C 2 H in several sources. We determined characteristic sizes of the gas disks and column densities of all molecules using a parametric power-law disk model. Our study is mostly sensitive to molecules at 200−400 au from the stars. We compared the derived column densities to the predictions of an extensive gas-grain chemical disk model under conditions representative of T Tauri disks.Results. This survey provides 20 new detections of HCO + in disks, 18 in HCN, 11 in C 2 H, 8 in CS, and 4 in SO. HCO + is detected in almost all sources and its J = 3−2 line is essentially optically thick, providing good estimates of the disk radii. The other transitions are (at least partially) optically thin. Large variations of the column density ratios are observed, but do not correlate with any specific property of the star or disk. Disks around Herbig Ae stars appear less rich in molecules than those around T Tauri stars, although the sample remains small. SO is only found in the (presumably younger) embedded objects, perhaps reflecting an evolution of the S chemistry due to increasing depletion with time. Overall, the molecular column densities, and in particular the CN/HCN and CN/C 2 H ratios, are well reproduced by gas-grain chemistry in cold disks. Conclusions. This study provides a comprehensive census of simple molecules in disks of radii >200−300 au. Extending that to smaller disks, or searching for less abundant or more complex molecules requires a much more sensitive facility, i.e., NOEMA and ALMA.

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“…In fact, this source is known to be a uniquely prominent outlier in terms of many of its properties, including showing weak and absent coronal lines (Goulding & Alexander 2009), potentially possessing a fully embedded AGN (Done et al 2003) and a putative obscuring torus with atypically low covering factor (e.g. Madejski et al 2000;Itoh et al 2008;Puccetti et al 2014). Much of the X-ray reflection signatures usually attributed to a circumnuclear torus instead appear to originate in clouds on much large scales associated with a starburst ring (Marinucci et al 2012), which may result in lack of hot dust in the immediate AGN environment.…”

Section: Comparison To Other Bona Fide Ctagnmentioning

confidence: 99%

A Compton-thick AGN in the barred spiral galaxy NGC 4785

Gandhi

Yamada

Ricci

et al. 2015

Monthly Notices of the Royal Astronomical Society

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We present X-ray observations of the active galactic nucleus (AGN) in NGC 4785. The source is a local Seyfert 2 which has not been studied so far in much detail. It was recently detected with high significance in the 15-60 keV band in the 66 month Swift/BAT all sky survey, but there have been no prior pointed X-ray observations of this object. With Suzaku, we clearly detect the source below 10 keV, and find it to have a flat continuum and prominent neutral iron fluorescence line with equivalent width ∼ > 1 keV. Fitting the broadband spectra with physical reflection models shows the source to be a bona fide Compton thick AGN with N H of at least 2 × 10 24 cm −2 and absorption-corrected 2-10 keV X-ray power L 2−10 ∼ few times 10 42 erg s −1 . Realistic uncertainties on L 2−10 computed from the joint confidence interval on the intrinsic power law continuum photon index and normalization are at least a factor of 10. The local bona fide Compton thick AGN population is highly heterogeneous in terms of WISE mid-infrared source colours, and the nucleus of NGC 4785 appears especially sub-dominant in the mid-infrared when comparing to other Compton thick AGN. Such sources would not be easily found using mid-infrared selection alone. The extent of host galaxy extinction to the nucleus is not clear, though NGC 4785 shows a complex core with a double bar and inner disk, adding to the list of known Compton thick AGN in barred host galaxies.

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Near-Infrared Coronagraphic Observations of a Classical T Tauri Star, DO Taurus

Cited by 13 publications

References 24 publications

Towards a complete census of active galactic nuclei in nearby galaxies: the incidence of growing black holes

Towards a complete census of active galactic nuclei in nearby galaxies: the incidence of growing black holes

Chemistry in disks

A Compton-thick AGN in the barred spiral galaxy NGC 4785

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