The Nuclear Region of NGC 1365: Star Formation, Negative Feedback, and Outflow Structure

In the framework of understanding the gas and stellar kinematics and their relations to AGNs and galaxy evolution scenarios, we present spatially resolved distributions and kinematics of the stars and gas in the central ∼800 pc radius of the nearby Seyfert galaxy NGC 1365. We obtained H + K- and K-band near-infrared (NIR) integral-field observations from VLT/SINFONI. Our results reveal strong broad and narrow emission-line components of ionized gas (hydrogen recombination lines Paα and Brγ) in the nuclear region, as well as hot dust with a temperature of ∼1300 K, both typical for type-1 AGNs. From MBH − σ* and the broad components of hydrogen recombination lines, we find a black-hole mass of (5 − 10)×106 M⊙. In the central ∼800 pc, we find a hot molecular gas mass of ∼615 M⊙, which corresponds to a cold molecular gas reservoir of (2 − 8)×108 M⊙. However, there is a molecular gas deficiency in the nuclear region. The gas and stellar-velocity maps both show rotation patterns consistent with the large-scale rotation of the galaxy. However, the gaseous and stellar kinematics show deviations from pure disk rotation, which suggest streaming motions in the central < 200 pc and a velocity twist at the location of the ring which indicates deviations in disk and ring rotation velocities in accordance with published CO kinematics. We detect a blueshifted emission line split in Paα, associated with the nuclear region only. We investigate the star-formation properties of the hot spots in the circumnuclear ring which have starburst ages of ≲10 Myr and find indications for an age gradient on the western side of the ring. In addition, our high-resolution data reveal further substructure within this ring which also shows enhanced star forming activity close to the nucleus.

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6.8. A multi wavelength study of the circumnuclear region of NGC 1365

Symposium - International Astronomical Union ◽

10.1017/s0074180900084916 ◽

1998 ◽

Vol 184 ◽

pp. 277-278

Author(s):

H. Kristen ◽

Aa. Sandqvist ◽

P.O. Lindblad

Keyword(s):

Active Galactic Nuclei ◽

Galactic Nuclei ◽

Radio Continuum ◽

Nuclear Region ◽

High Excitation ◽

Multi Wavelength ◽

Optical Wavelengths ◽

Barred Spiral Galaxy ◽

Seyfert Nucleus ◽

Ngc 1365

The nuclear region of the supergiant barred spiral galaxy NGC 1365 contains bright “hot spots”, as seen at optical wavelengths, as well as a number of non-thermal radio continuum sources, some of which remain unresolved at 0.25” × 0.10” resolution (Sandqvist et al. 1995, A&A 295, 585).The distribution of [OIII] λ5007 emission from the nuclear region supports the scenario of an [OIII] cone emanating from the Seyfert nucleus. The velocity field of the high excitation gas in the cone has been modeled by Hjelm & Lindblad (1996, A&A 305, 727) in terms of an accelerated bipolar conical outflow. Such conical or biconical high-excitation emission-line structures extending from the position of the nucleus are found in several active galactic nuclei.

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Star-Formation and Nuclear Activity in Three Galaxies with Nuclear Rings

Symposium - International Astronomical Union ◽

10.1017/s0074180900176417 ◽

1994 ◽

Vol 159 ◽

pp. 460-460

Author(s):

Thaisa Storchi–Bergmann ◽

Andrew S. Wilson ◽

Jack A. Baldwin

Keyword(s):

Black Hole ◽

Star Formation ◽

Galactic Nuclei ◽

High Spectral Resolution ◽

Nuclear Region ◽

Chemical Abundance ◽

Chemical Abundances ◽

Nuclear Activity ◽

Line Region ◽

Low Dispersion

We investigate two current problems in active galactic nuclei – the mode of fueling the putative black hole, and the question whether the circumnuclear regions have experienced unusual chemical processing – by studying the kinematics and chemical abundance of the gas in the nuclear region of galaxies with sites of ongoing star formation near the active nucleus. We discuss the results for three galaxies with nuclear rings: NGC1097 – for which we recently discovered broad double peaked Hα and Hβ emission from its LINER nucleus (Storchi-Bergmann, Baldwin & Wilson 1993, ApJ 410, L11); NGC1672, which also presents a LINER nucleus; and NGC5248, a galaxy with a ring but no nuclear activity, used as a comparison. Narrow–band images obtained with the CTIO 1.5m telescope were used to map the emitting gas. Longslit spectroscopy obtained with the 4m telescope at high spectral resolution (at several positions over the nuclear region) was used to obtain the gas velocity field. In the two galaxies with LINER nucleus, the starforming rings are located in the turnover of the rotation curves, which show that the gas is rotating faster at the rings than farther out. We conclude that the rings are associated with inner Lindblad ressonances, which may be particularly effective in forcing gas inwards and fuelling the black hole (Wilson et al. 1986, ApJ 310, 121). From the emission line ratios the gas excitation is maped, and it is found that even in NGC5248, the nucleus presents a different excitation, suggesting a very mild LINER activity. Low-dispersion spectroscopy was also obtained in order to calculate the chemical abundances and compare the values obtained for the nuclear gas with those obtained for the HII regions in the ring and beyond the ring (when present). The goal is to check the results of recent studies (Storchi-Bergmann & Pastoriza 1989, ApJ 347, 195; 1990, PASP 102, 1359), based on spectroscopy of the nucleus, which indicate an enhanced abundance of nitrogen, up to 5 times solar for the gas of the narrow line region of LINER and Seyfert 2 nuclei.

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Lessons from comparisons between the nuclear region of the Milky Way and those in nearby spirals

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314000155 ◽

2013 ◽

Vol 9 (S303) ◽

pp. 61-65

Author(s):

John S. Gallagher ◽

Tova M. Yoast-Hull ◽

Ellen G. Zweibel

Keyword(s):

Star Formation ◽

Milky Way ◽

Star Formation Rate ◽

Formation Rate ◽

Molecular Gas ◽

Nuclear Region ◽

Stellar Content ◽

Nuclear Regions ◽

Stellar Masses

AbstractThe Milky Way appears as a typical barred spiral, and comparisons can be made between its nuclear region and those of structurally similar nearby spirals. Maffei 2, M83, IC 342 and NGC 253 are nearby systems whose nuclear region properties contrast with those of the Milky Way. Stellar masses derived from NIR photometery, molecular gas masses and star formation rates allow us to assess the evolutionary states of this set of nuclear regions. These data suggest similarities between nuclear regions in terms of their stellar content while highlighting significant differences in current star formation rates. In particular current star formation rates appear to cover a larger range than expected based on the molecular gas masses. This behavior is consistent with nuclear region star formation experiencing episodic variations. Under this hypothesis the Milky Way's nuclear region currently may be in a low star formation rate phase.

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Kiso Hα Imaging Observations of Nearby Galaxies

Publications of the Astronomical Society of Australia ◽

10.1071/as98149 ◽

1998 ◽

Vol 15 (1) ◽

pp. 149-151

Author(s):

T. Hasegawa ◽

S. Sakamoto ◽

S. Nishiura ◽

Y. Ohyama ◽

Y. Sofue

Keyword(s):

Star Formation ◽

Compact Group ◽

Spiral Galaxy ◽

Clear Correlation ◽

Nuclear Region ◽

Diffuse Emission ◽

Schmidt Telescope ◽

Group System ◽

Nearby Galaxies ◽

Formation Efficiency

AbstractWe report Hα imaging observations of nearby galaxies with the Kiso Schmidt telescope. For spiral galaxy NGC 628, we found no clear correlation between Hα and CO intensities, and we discuss the star formation efficiency of this galaxy. No nuclear Hα emission in this galaxy was detected. This is consistent with spectroscopic observations which indicate that the nuclear region is in the post starburst phase. We also describe the Hα image of Hickson's compact group 92 in which diffuse emission is detected extending within the group system.

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M 31 circum-nuclear region: A molecular survey with the IRAM interferometer

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834069 ◽

2019 ◽

Vol 625 ◽

pp. A148

Author(s):

Julien Dassa-Terrier ◽

Anne-Laure Melchior ◽

Françoise Combes

Keyword(s):

Star Formation ◽

Spectral Energy Distribution ◽

Formation Rate ◽

Dust Emission ◽

Critical Density ◽

Local Thermal Equilibrium ◽

Spectral Energy ◽

Nuclear Region ◽

Mass Size ◽

Size Relation

We analysed molecular observations performed at IRAM interferometer in CO(1-0) of the circum-nuclear region (within 250 pc) of Andromeda with 2.9″ = 11 pc resolution. We detected 12 molecular clumps in this region, corresponding to a total molecular mass of (8.4 ± 0.4)×104 M⊙. These clumps follow Larson’s mass-size relation, but lie well above the velocity-size relation. We discuss the possibility that these clumps are probably not virialised, but are transient agglomerations of smaller entities that might be virialised. Three of these clumps have been detected in CO(2-1) in a previous work, and we find a temperature line ratio below 0.5 in this work. With a radiative transfer analysis, we show that this gas is in non-local thermal equilibrium with a low excitation temperature (Tex = 5 − 9 K). We find a surface beam filling factor of order 5% and a gas density in the range 60 − 650 cm−3, which is well below the critical density. With a gas-to-stellar mass fraction of 4 × 10−4 and dust-to-gas ratio of 0.01, this quiescent region has exhausted its gas budget. Its spectral energy distribution is compatible with passive templates assembled from elliptical galaxies. While weak dust emission is present in the region, we show that no star formation is present and support the previous results that the dust is heated by the old and intermediate stellar population. We study the possibility that this region lies formally in the low-density part of the Kennicutt-Schmidt law in a regime where the star formation rate estimators are not completely reliable. We confirm the quiescence of the inner part of this galaxy known to lie on the green valley.

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Feeding and feedback in nearby AGN – comparison with the Milky Way center

Proceedings of the International Astronomical Union ◽

10.1017/s174392131400091x ◽

2013 ◽

Vol 9 (S303) ◽

pp. 354-363 ◽

Cited By ~ 3

Author(s):

T. Storchi-Bergmann

Keyword(s):

Star Formation ◽

Milky Way ◽

Galactic Center ◽

Formation Rate ◽

Activity Cycle ◽

Nuclear Region ◽

Nuclear Activity ◽

The Galaxy ◽

Mass Outflow ◽

Sgr A

AbstractI discuss feeding and feedback processes observed in the inner few hundred parsecs of nearby active galaxies using integral field spectroscopy at spatial resolutions of a few to tens of parsecs. Signatures of feedback include outflows from the nucleus with velocities ranging from 200 to 1000 km s−1, with mass outflow rates between 0.5 and a few M⊙ yr−1. Signatures of feeding include the observation of gas inflows along nuclear spirals and filaments, with velocities ranging from 50 to 100 km s−1 and mass flow rates from 0.1 to ∼1 M⊙ yr−1. These rates are 2–3 orders of magnitude larger than the mass accretion rate to the supermassive black hole (SMBH). These inflows can thus lead, during less than one activity cycle, to the accumulation of enough gas in the inner few hundred parsecs, to trigger the formation of new stars, leading to the growth of the galaxy bulge. Young to intermediate age stars have indeed been found in circumnuclear rings around a number of Active Galactic Nuclei (AGN). In particular, one of these rings, with radius of ≈ 100 pc is observed in the Seyfert 2 galaxy NGC 1068, and is associated to an off-centered molecular ring, very similar to that observed in the Milky Way (MW). On the basis of an evolutionary scenario in which gas falling into the nuclear region triggers star formation followed by the triggering of nuclear activity, we speculate that, in the case of the MW, molecular gas has already accumulated within the inner ≈ 100 pc to trigger the formation of new stars, as supported by the presence of blue stars close to the galactic center. A possible increase in the star-formation rate in the nuclear region will then be followed, probably tens of millions of years later, by the triggering of nuclear activity in Sgr A*.

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Understanding galaxy mergers and AGN feedback with UVIT

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320003300 ◽

2019 ◽

Vol 15 (S356) ◽

pp. 345-347

Author(s):

Khatun Rubinur ◽

Mousumi Das ◽

Preeti Kharb ◽

P. T. Rahne

Keyword(s):

Star Formation ◽

Pilot Study ◽

Active Galactic Nuclei ◽

Negative Feedback ◽

Galactic Nuclei ◽

Galaxy Mergers ◽

Imaging Telescope ◽

Multi Wavelength ◽

Initial Results

AbstractSimulations expect an enhanced star-formation and active galactic nuclei (AGN) activity during galaxy mergers, which can lead to formation of binary/dual AGN. AGN feedback can enhance or suppress star-formation. We have carried out a pilot study of a sample of ˜10 dual nuclei galaxies with AstroSat’s Ultraviolet Imaging Telescope (UVIT). Here, we present the initial results for two sample galaxies (Mrk 739, ESO 509) and deep multi-wavelength data of another galaxy (Mrk 212). UVIT observations have revealed signatures of positive AGN feedback in Mrk 739 and Mrk 212, and negative feedback in ESO 509. Deeper UVIT observations have recently been approved; these will provide better constraints on star-formation as well as AGN feedback in these systems.

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Negative feedback effects on star formation history and cosmic reionization

Astronomy and Astrophysics ◽

10.1051/0004-6361/200809916 ◽

2009 ◽

Vol 494 (3) ◽

pp. 817-827 ◽

Cited By ~ 2

Author(s):

L. Wang ◽

J. Mao ◽

S. Xiang ◽

Y.-F. Yuan

Keyword(s):

Star Formation ◽

Negative Feedback ◽

Star Formation History ◽

Feedback Effects ◽

Formation History

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Insights on bar quenching from a multiwavelength analysis: The case of Messier 95

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834500 ◽

2019 ◽

Vol 621 ◽

pp. L4 ◽

Cited By ~ 10

Author(s):

K. George ◽

P. Joseph ◽

C. Mondal ◽

S. Subramanian ◽

A. Subramaniam ◽

...

Keyword(s):

Star Formation ◽

Molecular Hydrogen ◽

Stellar Population ◽

Major Axis ◽

Nuclear Region ◽

Imaging Data ◽

Physical Processes ◽

Star Forming ◽

The Galaxy ◽

Barred Spiral Galaxy

The physical processes related to the effect of bars in the quenching of star formation in the region between the nuclear/central sub-kiloparsec region and the ends of the bar (bar region) of spiral galaxies is not fully understood. It is hypothesized that the bar can either stabilize the gas against collapse, inhibiting star formation, or efficiently consume all the available gas, leaving no fuel for further star formation. We present a multiwavelength study using the archival data of an early-type barred spiral galaxy, Messier 95, which shows signatures of suppressed star formation in the bar region. Using optical, ultraviolet (UV), infrared, CO, and HI imaging data we study the pattern of star formation progression and stellar/gas distribution, and try to provide insights into the process responsible for the observed pattern. The FUV–NUV pixel colour map reveals a cavity devoid of UV flux in the bar region that matches the length of the bar, which is ∼4.2 kpc. The central nuclear region of the galaxy shows a blue colour clump and along the major axis of the stellar bar the colour progressively becomes redder. Based on a comparison to single stellar population models, we show that the region of galaxy along the major axis of the bar, unlike the region outside the bar, is comprised of stellar populations with ages ≥350 Myr; there is a star-forming clump in the centre of younger ages of ∼150 Myr. Interestingly the bar region is also devoid of neutral and molecular hydrogen but has an abundant molecular hydrogen present at the nuclear region of the galaxy. Our results are consistent with a picture in which the stellar bar in Messier 95 is redistributing the gas by funnelling gas inflows to nuclear region, thus making the bar region devoid of fuel for star formation.

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