Masers in Starburst Galaxies

AbstractMasers in starburst galaxies are outstanding probes of a range of phenomena related to galaxy and black hole evolution, star formation, and magnetic fields. Here I briefly discuss five related topics: (1) Galactic analog water masers in nearby galaxies; (2) multiwavelength solutions to the OH megamaser puzzle in major galaxy mergers; (3) formaldehyde anti-inversion in starburst galaxies; (4) OH spoofing in HI surveys; and (5) new discovery space in radio line surveys. New insights into the physical conditions responsible for OH megamasers, including indications of a critical molecular gas density obtained from the formaldehyde “densitometer,” will be applicable to future surveys, particularly surveys for redshifted hydrogen where OH lines arising in major galaxy mergers can “contaminate” the disk population identified by the HI 21 cm line. Blind radio spectral line surveys also offer the opportunity for unexpected discoveries of new nonthermal radio lines.

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The ALMaQUEST Survey – II. What drives central starbursts at z ∼ 0?

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa001 ◽

2020 ◽

Vol 492 (4) ◽

pp. 6027-6041 ◽

Cited By ~ 6

Author(s):

Sara L Ellison ◽

Mallory D Thorp ◽

Hsi-An Pan ◽

Lihwai Lin ◽

Jillian M Scudder ◽

...

Keyword(s):

Star Formation ◽

Surface Density ◽

Stellar Mass ◽

Starburst Galaxies ◽

Molecular Gas ◽

Central Regions ◽

Primary Driver ◽

Nearby Galaxies ◽

Field Unit ◽

Formation Efficiency

ABSTRACT Starburst galaxies have elevated star formation rates (SFRs) for their stellar mass. In Ellison et al., we used integral field unit maps of SFR surface density (ΣSFR) and stellar mass surface density (Σ⋆) to show that starburst galaxies in the local universe are driven by SFRs that are preferentially boosted in their central regions. Here, we present molecular gas maps obtained with the Atacama Large Millimeter Array (ALMA) observatory for 12 central starburst galaxies at z ∼ 0 drawn from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey. The ALMA and MaNGA data are well matched in spatial resolution, such that the ALMA maps of molecular gas surface density ($\Sigma _{\rm H_2}$) can be directly compared with MaNGA maps at kpc-scale resolution. The combination of $\Sigma _{\rm H_2}$, Σ⋆ and ΣSFR at the same resolution allow us to investigate whether central starbursts are driven primarily by enhancements in star formation efficiency (SFE) or by increased gas fractions. By computing offsets from the resolved Kennicutt-Schmidt relation ($\Sigma _{\rm H_2}$ versus ΣSFR) and the molecular gas main sequence (Σ⋆ versus $\Sigma _{\rm H_2}$), we conclude that the primary driver of the central starburst is an elevated SFE. We also show that the enhancement in ΣSFR is accompanied by a dilution in O/H, consistent with a triggering that is induced by metal poor gas inflow. These observational signatures are found in both undisturbed (9/12 galaxies in our sample) and recently merged galaxies, indicating that both interactions and secular mechanisms contribute to central starbursts.

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The link between star formation and gas in nearby galaxies

Communications Physics ◽

10.1038/s42005-020-00493-0 ◽

2020 ◽

Vol 3 (1) ◽

Author(s):

Robert Feldmann

Keyword(s):

Star Formation ◽

Gas Content ◽

Molecular Gas ◽

Galaxy Mergers ◽

Physical Processes ◽

Star Forming ◽

Star Formation Activity ◽

Star Formation In Galaxies ◽

Nearby Galaxies ◽

Gas Accretion

AbstractObservations of the interstellar medium are key to deciphering the physical processes regulating star formation in galaxies. However, observational uncertainties and detection limits can bias the interpretation unless carefully modeled. Here I re-analyze star formation rates and gas masses of a representative sample of nearby galaxies with the help of multi-dimensional Bayesian modeling. Typical star forming galaxies are found to lie in a ‘star forming plane’ largely independent of their stellar mass. Their star formation activity is tightly correlated with the molecular and total gas content, while variations of the molecular-gas-to-star conversion efficiency are shown to be significantly smaller than previously reported. These data-driven findings suggest that physical processes that modify the overall galactic gas content, such as gas accretion and outflows, regulate the star formation activity in typical nearby galaxies, while a change in efficiency triggered by, e.g., galaxy mergers or gas instabilities, may boost the activity of starbursts.

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Central kiloparsec of NGC 1326 observed with SINFONI

Astronomy and Astrophysics ◽

10.1051/0004-6361/201936451 ◽

2020 ◽

Vol 638 ◽

pp. A53

Author(s):

Nastaran Fazeli ◽

Gerold Busch ◽

Andreas Eckart ◽

Françoise Combes ◽

Persis Misquitta ◽

...

Keyword(s):

Black Hole ◽

Galaxy Evolution ◽

Near Infrared ◽

Velocity Fields ◽

Molecular Gas ◽

Nearby Galaxy ◽

Stellar Content ◽

Stellar Rotation ◽

Supermassive Black Hole ◽

Integral Field Spectrograph

Gas inflow processes in the vicinity of galactic nuclei play a crucial role in galaxy evolution and supermassive black hole growth. Exploring the central kiloparsec of galaxies is essential to shed more light on this subject. We present near-infrared H- and K-band results of the nuclear region of the nearby galaxy NGC 1326, observed with the integral-field spectrograph SINFONI mounted on the Very Large Telescope. The field of view covers 9″ × 9″ (650 × 650 pc2). Our work is concentrated on excitation conditions, morphology, and stellar content. The nucleus of NGC 1326 was classified as a LINER, however in our data we observed an absence of ionised gas emission in the central r ∼ 3″. We studied the morphology by analysing the distribution of ionised and molecular gas, and thereby detected an elliptically shaped, circum-nuclear star-forming ring at a mean radius of 300 pc. We estimate the starburst regions in the ring to be young with dominating ages of < 10 Myr. The molecular gas distribution also reveals an elongated east to west central structure about 3″ in radius, where gas is excited by slow or mild shock mechanisms. We calculate the ionised gas mass of 8 × 105 M⊙ completely concentrated in the nuclear ring and the warm molecular gas mass of 187 M⊙, from which half is concentrated in the ring and the other half in the elongated central structure. The stellar velocity fields show pure rotation in the plane of the galaxy. The gas velocity fields show similar rotation in the ring, but in the central elongated H2 structure they show much higher amplitudes and indications of further deviation from the stellar rotation in the central 1″ aperture. We suggest that the central 6″ elongated H2 structure might be a fast-rotating central disc. The CO(3–2) emission observations with the Atacama Large Millimeter/submillimeter Array reveal a central 1″ torus. In the central 1″ of the H2 velocity field and residual maps, we find indications for a further decoupled structure closer to a nuclear disc, which could be identified with the torus surrounding the supermassive black hole.

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WISDOM project – VII. Molecular gas measurement of the supermassive black hole mass in the elliptical galaxy NGC 7052

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab791 ◽

2021 ◽

Vol 503 (4) ◽

pp. 5984-5996

Author(s):

Mark D Smith ◽

Martin Bureau ◽

Timothy A Davis ◽

Michele Cappellari ◽

Lijie Liu ◽

...

Keyword(s):

Black Hole ◽

Hubble Space Telescope ◽

Elliptical Galaxy ◽

Continuum Emission ◽

Molecular Gas ◽

Supermassive Black Hole ◽

Gas Kinematics ◽

Long Baseline ◽

Gas Measurement ◽

Strong Gradient

ABSTRACT Supermassive black hole (SMBH) masses can be measured by resolving the dynamical influences of the SMBHs on tracers of the central potentials. Modern long-baseline interferometers have enabled the use of molecular gas as such a tracer. We present here Atacama Large Millimeter/submillimeter Array observations of the elliptical galaxy NGC 7052 at 0${^{\prime\prime}_{.}}$11 ($37\,$pc) resolution in the 12CO(2-1) line and $1.3\,$ mm continuum emission. This resolution is sufficient to resolve the region in which the potential is dominated by the SMBH. We forward model these observations, using a multi-Gaussian expansion of a Hubble Space Telescope F814W image and a spatially constant mass-to-light ratio to model the stellar mass distribution. We infer an SMBH mass of $2.5\pm 0.3\times 10^{9}\, \mathrm{M_\odot }$ and a stellar I-band mass-to-light ratio of $4.6\pm 0.2\, \mathrm{M_\odot /L_{\odot ,I}}$ (3σ confidence intervals). This SMBH mass is significantly larger than that derived using ionized gas kinematics, which however appears significantly more kinematically disturbed than the molecular gas. We also show that a central molecular gas deficit is likely to be the result of tidal disruption of molecular gas clouds due to the strong gradient in the central gravitational potential.

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Morphological evolution of supermassive black hole merger hosts and multimessenger signatures

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab721 ◽

2021 ◽

Vol 503 (3) ◽

pp. 3629-3642

Author(s):

Colin DeGraf ◽

Debora Sijacki ◽

Tiziana Di Matteo ◽

Kelly Holley-Bockelmann ◽

Greg Snyder ◽

...

Keyword(s):

Black Holes ◽

Black Hole ◽

Star Formation ◽

Morphological Evolution ◽

Full Range ◽

High Mass ◽

Morphological Evidence ◽

Galaxy Mergers ◽

Host Galaxies ◽

Supermassive Black Hole

ABSTRACT With projects such as Laser Interferometer Space Antenna (LISA) and Pulsar Timing Arrays (PTAs) expected to detect gravitational waves from supermassive black hole mergers in the near future, it is key that we understand what we expect those detections to be, and maximize what we can learn from them. To address this, we study the mergers of supermassive black holes in the Illustris simulation, the overall rate of mergers, and the correlation between merging black holes and their host galaxies. We find these mergers occur in typical galaxies along the MBH−M* relation, and that between LISA and PTAs we expect to probe the full range of galaxy masses. As galaxy mergers can trigger star formation, we find that galaxies hosting low-mass black hole mergers tend to show a slight increase in star formation rates compared to a mass-matched sample. However, high-mass merger hosts have typical star formation rates, due to a combination of low gas fractions and powerful active galactic nucleus feedback. Although minor black hole mergers do not correlate with disturbed morphologies, major mergers (especially at high-masses) tend to show morphological evidence of recent galaxy mergers which survive for ∼500 Myr. This is on the same scale as the infall/hardening time of merging black holes, suggesting that electromagnetic follow-ups to gravitational wave signals may not be able to observe this correlation. We further find that incorporating a realistic time-scale delay for the black hole mergers could shift the merger distribution towards higher masses, decreasing the rate of LISA detections while increasing the rate of PTA detections.

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An accreting < 105M⊙ black hole at the center of dwarf galaxy IC750

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320003488 ◽

2019 ◽

Vol 15 (S356) ◽

pp. 376-376

Author(s):

Ingyin Zaw

Keyword(s):

Black Holes ◽

Black Hole ◽

Dwarf Galaxies ◽

Dwarf Galaxy ◽

Host Galaxy ◽

Scaling Relations ◽

Host Galaxies ◽

Seed Formation ◽

Maser Emission ◽

Water Masers

AbstractNuclear black holes in dwarf galaxies are important for understanding the low end of the supermassive black hole mass distribution and the black hole-host galaxy scaling relations. IC 750 is a rare system which hosts an AGN, found in ˜0.5% of dwarf galaxies, with circumnuclear 22 GHz water maser emission, found in ˜3–5% of Type 2 AGNs. Water masers, the only known tracer of warm, dense gas in the center parsec of AGNs resolvable in position and velocity, provide the most precise and accurate mass measurements of SMBHs outside the local group. We have mapped the maser emission in IC 750 and find that it traces a nearly edge-on warped disk, 0.2 pc in diameter. The central black hole has an upper limit mass of ˜1 × 105 M⊙ and a best fit mass of ˜8 × 104 M⊙, one to two orders of magnitude below what is expected from black hole-galaxy scaling relations. This has implications for models of black hole seed formation in the early universe, the growth of black holes, and their co-evolution with their host galaxies.

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SDSS J154751.94+025550 with double-peaked broad H β but single-peaked broad H α: a candidate for central binary black hole system?

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab2433 ◽

2021 ◽

Vol 507 (4) ◽

pp. 5205-5213

Author(s):

XueGuang Zhang

Keyword(s):

Black Hole ◽

Active Galactic Nuclei ◽

Galactic Nuclei ◽

Emission Lines ◽

Broad Line ◽

Line Profiles ◽

Physical Conditions ◽

Binary Black Hole ◽

Sinusoidal Function

ABSTRACT In this manuscript, an interesting blue active galactic nuclei (AGNs) SDSS J154751.94+025550 (=SDSS J1547) is reported with very different line profiles of broad Balmer emission lines: double-peaked broad H β but single-peaked broad H α. SDSS J1547 is the first AGN with detailed discussions on very different line profiles of the broad Balmer emission lines, besides the simply mentioned different broad lines in the candidate for a binary black hole (BBH) system in SDSS J0159+0105. The very different line profiles of the broad Balmer emission lines can be well explained by different physical conditions to two central BLRs in a central BBH system in SDSS J1547. Furthermore, the long-term light curve from CSS can be well described by a sinusoidal function with a periodicity about 2159 d, providing further evidence to support the expected central BBH system in SDSS J1547. Therefore, it is interesting to treat different line profiles of broad Balmer emission lines as intrinsic indicators of central BBH systems in broad line AGN. Under assumptions of BBH systems, 0.125 per cent of broad-line AGN can be expected to have very different line profiles of broad Balmer emission lines. Future study on more broad line AGN with very different line profiles of broad Balmer emission lines could provide further clues on the different line profiles of broad Balmer emission lines as indicator of BBH systems.

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