17 pages, 12 figures
Negative feedback from accreting supermassive black holes is regarded as a key ingredient in suppressing star formation and quenching massive galaxies. However, several models and observations suggest that black hole feedback may have a positive effect, triggering star formation by compressing interstellar medium gas to higher densities. We investigate the dual role of black hole feedback using cosmological hydrodynamic simulations from the Feedback In Realistic Environments (FIRE) project, including a novel implementation of hyper-refined accretion-disc winds. Focusing on a massive, star-forming galaxy at $z \sim 2$ ($M_{\rm halo} \sim 10^{12.5} \, {\rm M}_{\odot}$), we show that strong quasar winds with kinetic power $\sim$10$^{46}$ erg/s acting for $>$20$\,$Myr drive the formation of a central gas cavity and can dramatically reduce the star formation rate surface density across the galaxy disc. The suppression of star formation is primarily driven by reducing the amount of gas that can become star-forming, compared to directly evacuating the pre-existing star-forming gas reservoir (preventive feedback dominates over ejective feedback). Despite the global negative impact of quasar winds, we identify several plausible signatures of local positive feedback, including: (1) spatial anti-correlation of wind-dominated regions and star-forming clumps, (2) higher local star formation efficiency in compressed gas near the edge of the cavity, and (3) increased local contribution of outflowing material to star formation. Stars forming under the presence of quasar winds tend to do so at larger radial distances. Our results suggest that positive and negative AGN feedback can coexist in galaxies, but local positive triggering of star formation plays a minor role in global galaxy growth.
29 pages, 7 figures, Accepted for publication in MNRAS
We present ALMA Band-3/7 observations towards "the Heart" of a massive hub-filament system (HFS) SDC335, to investigate its fragmentation and accretion. At a resolution of $\sim0.03$ pc, 3 mm continuum emission resolves two massive dense cores MM1 and MM2, with $383(^{+234}_{-120})$ $M_\odot$ (10-24% mass of "the Heart") and $74(^{+47}_{-24})$ $M_\odot$, respectively. With a resolution down to 0.01 pc, 0.87 mm continuum emission shows MM1 further fragments into six condensations and multi-transition lines of H$_2$CS provide temperature estimation. The relation between separation and mass of condensations at a scale of 0.01 pc favors turbulent Jeans fragmentation where the turbulence seems to be scale-free rather than scale-dependent. We use the H$^{13}$CO$^+$ (1-0) emission line to resolve the complex gas motion inside "the Heart" in position-position-velocity space. We identify four major gas streams connected to large-scale filaments, inheriting the anti-clockwise spiral pattern. Along these streams, gas feeds the central massive core MM1. Assuming an inclination angle of $45(\pm15)^{\circ}$ and a H$^{13}$CO$^+$ abundance of $5(\pm3)\times10^{-11}$, the total mass infall rate is estimated to be $2.40(\pm0.78)\times10^{-3}$ $M_\odot$ yr$^{-1}$, numerically consistent with the accretion rates derived from the clump-scale spherical infall model and the core-scale outflows. The consistency suggests a continuous, near steady-state, and efficient accretion from global collapse, therefore ensuring core feeding. Our comprehensive study of SDC335 showcases the detailed gas kinematics in a prototypical massive infalling clump and calls for further systematic and statistical analyses in a large sample.
4 pages, 1 figure, to be published in RNAAS
We examined the period distribution of transit-like signatures uncovered in a Box-Least Squares transit search of TESS light curves, and show significant pileups at periods related to instrumental and astrophysical noise sources. Signatures uncovered in a search of inverted light curves feature similar structures in the period distribution. Automated vetting methods will need to remove these excess detections, and light curve inversion appears to be a suitable method for simulating false alarms and designing new vetting metrics.
34 pages with 20 figures, Accepted by MNRAS on 2022 December 28
Whether ionization feedback triggers the formation of massive stars is highly debated. Using ALMA 3 mm observations with a spatial resolution of $\sim 0.05$ pc and a mass sensitivity of 1.1 $\rm M_\odot$ beam$^{-1}$ at 20 K, we investigate the star formation and gas flow structures within the ionizing feedback-driven structure, a clump-scale massive ($\gtrsim 1500$ $\rm M_\odot$) bright-rimmed cloud (BRC) associated with IRAS 18290-0924. This BRC is bound only if external compression from ionized gas is considered. A small-scale ($\lesssim1$ pc) age sequence along the direction of ionizing radiation is revealed for the embedded cores and protostars, which suggests triggered star formation via radiation-driven implosion (RDI). Furthermore, filamentary gas structures converge towards the cores located in the BRC's center, indicating that these filaments are fueling mass towards cores. The local core-scale mass infall rate derived from H$^{13}$CO$^+$ $J=1-0$ blue profile is of the same order of magnitude as the filamentary mass inflow rate, approximately 1 $\rm M_\odot$ kyr$^{-1}$. A photodissociation region (PDR) covering the irradiated clump surface is detected in several molecules, such as CCH, HCO$^+$, and CS whereas the spatial distribution stratification of these molecules is indistinct. CCH spectra of the PDR possibly indicate a photoevaporation flow leaving the clump surface with a projected velocity of $\sim2$ km s$^{-1}$. Our new observations show that RDI accompanied by a clump-fed process is operating in this massive BRC. Whether this combined process works in other massive BRCs is worth exploring with dedicated surveys.
30 pages, 13 figures; accepted for publication in ApJ
G10.21-0.31 is a 70 $\mu$m-dark high-mass starless core ($M>300$ $\mathrm{M_{\odot}}$ within $r<0.15$ pc) identified in $Spitzer$, $Herschel$, and APEX continuum surveys, and is believed to harbor the initial stages of high-mass star formation. We present ALMA and SMA observations to resolve the internal structure of this promising high-mass starless core. Sensitive high-resolution ALMA 1.3 mm dust continuum emission reveals three cores of mass ranging 11-18 $\mathrm{M_{\odot}}$, characterized by a turbulent fragmentation. Core 1, 2, and 3 represent a coherent evolution at three different evolutionary stages, characterized by outflows (CO, SiO), gas temperature ($\mathrm{H_2CO}$), and deuteration ($\mathrm{N_2D^+/N_2H^+}$). We confirm the potential to form high-mass stars in G10.21 and explore the evolution path of high-mass star formation. Yet, no high-mass prestellar core is present in G10.21. This suggests a dynamical star formation where cores grow in mass over time.
9 pages, submitted
23 pages, 17 figures. Accepted for publication in ApJ
10 pages, 10 figures, accepted for publication in MNRAS
accepted by PASP for JWST Overview Special Issue; 34 pages, 25 figures
15 pages, 4 figures, accepted for publication in ApJ
Published in The Astrophysical Journal Letters (published 2022 December 22)
16 pages + 5 page appendix, 17+9 figures, 3+2 tables. Accepted for publication in A&A
7 pages, 4 figures, MNRAS, in press
38 pages, 11 figures
submitted to MNRAS. 11 pages, 8 figures
57 pages, 61 figures, 12 tables; accepted to Astron.J
38 pages, 20 figures. Data access and details about the catalog can be found online at this http URL A copy of the catalogs presented in this work (Version 3.2) is available to download at Zenodo doi:10.5281/zenodo.7448504
Submitted to MNRAS Comments welcome
20 pages, 12 figures, 4 tables, Accepted for publication in ApJ
27 pages, 10 figures. Accepted for publication in The Astrophysical Journal Supplement Series (ApJS)
6 pages, 5 figures, 1 table, accepted to be published in MNRAS
16 pages, 17 figures, submitted to A&A
25 pages, 6 figures
The paper has been accepted in MNRAS on January 3rd, 2023
16 pages, 14 figures, submitted to MNRAS. Comments welcome!
13 pages, 6 figures, Accepted for publication in ApJ. The movie corresponding to Fig.3 (which demonstrates the result better) is available at this http URL
12 pages, 6 figures, accepted for publication in The Astrophysical Journal
14 pages, 8 figures
15 Pages, 11 Figures, Accepted in Journal of Astrophysics and Astronomy (JAA)
14 pages, 6 figures
Accepted for publication in Astronomy & Astrophysics. 22 pages, 15 figures, 5 tables
21 figures, 4 tables. To be published in Solar Physics
9 pages, 6 figures. Accepted for publication in MNRAS
25 pages, 13 figures
Accepted by MNRAS
Accepted in ICARUS in 05/01/2023 (YICAR_115428)
26 pages, 16 figures, accepted to ApJ
5 pages plus appendix. Accepted for publication in A&A
12 pages, 5 figures. Accepted for publication in Icarus
Submitted to ApJ
18 pages, 15 figures. Comments are welcome
30 pages, 18 figures (including appendices), submitted to ApJ
9 pages, 3 figures, 1 table, 28 references
4 pages, 2 figures, 3 tables
21 pages, 5 figures
10 pages, 5 figures
12 pages, 1 figures
15 pages, no figures
12 pages