Astronomy

2019 Dec 17

BHI Colloquium

1:30pm to 2:30pm

Location: 

BHI Meeting Room

Marek Abramowicz (Copernicus Center, Warsaw)

Title: TBD

Abstract: TBD

Bhupendra Mishra (JILA, Boulder)

Title: TBD

Abstract: TBD

Debora Lancova (Opava University)

Title: TBD

Abstract: TBD

Read more about BHI Colloquium
Selma de Mink

Selma de Mink

Faculty Affiliate, Black Hole Initiative
Associate Professor in Astrophysics, Harvard University

Selma de Mink is a Dutch astrophycisist. She is a Professor of Astrophysics at the Astronomy department and Institute for Theory and Computation at...

Read more about Selma de Mink
2019 Apr 09

Yakov Shlapentokh-Rothman: Princeton University & Roberto Emperan: Universitat de Barcelona

1:00pm to 3:00pm

Location: 

BHI conference Room: 20 Garden Street, Cambridge (Lunch will be served at 1:00 pm)

Yakov Shlapentokh-Rothman: Princeton University

Title: Superradiant Instabilities for Massive Scalar Fields on Kerr Black Hole Backgrounds

Abstract: Superradiance refers to the possibility of energy extraction from a rotating black. We will discuss how this phenomenon leads to instabilities in the propagation of massive...

Read more about Yakov Shlapentokh-Rothman: Princeton University & Roberto Emperan: Universitat de Barcelona
Lindy

Lindy Blackburn

SAO Radio Astronomer, Harvard-Smithsonian Center for Astrophysics
Dom Pesce

Dominic Pesce

EHT Postdoctoral Fellow
PhD University of Virginia

Dom is a postdoctoral fellow for the Event Horizon Telescope collaboration, working primarily on modeling and feature extraction techniques. He graduated...

Read more about Dominic Pesce
Brandon Curd

Brandon Curd

Phd student, Department of Astronomy
Brandon is doing his doctoral work in the Astronomy Department. He works with Professor Narayan on general relativistic radiation magnetohydrodynamics... Read more about Brandon Curd
Daniel Palumbo

Daniel Palumbo

PhD student: Harvard University, BHI

I am a graduate student in the Astronomy department at Harvard University. I work with the Event Horizon Telescope to form images from Very-Long-Baseline...

Read more about Daniel Palumbo
xiawei wang

Xiawei Wang

Phd student: Harvard University, Department of Astronomy
2018 Apr 03

BHI Colloquium, April 3 I "​Not quite a black hole: from quadratic gravity to gravitational wave echoes," Jing Ren and "A Galaxy-Scale Fountain of Cold Molecular Gas Pumped by a Black Hole," Grant Tremblay

1:30pm

Location: 

BHI Conference Room (211) 20 Garden Street, Cambridge

Jing Ren

University of Toronto

​Title: Not quite a black hole: from quadratic gravity to gravitational wave echoes

Abstract:

​Astrophysical black hole candidates might be horizonless ultracompact objects. Of particular interest is the plausible fundamental connection with quantum...

Read more about BHI Colloquium, April 3 I "​Not quite a black hole: from quadratic gravity to gravitational wave echoes," Jing Ren and "A Galaxy-Scale Fountain of Cold Molecular Gas Pumped by a Black Hole," Grant Tremblay
2018 Mar 27

BHI Colloquium, March 27 | "​On the distinguishability of black hole microstates," Andrea Puhm | "Discovery and Opportunity in the X-ray Time Domain," Daryl Haggard

1:30pm

Location: 

BHI Conference Room (211) 20 Garden Street, Cambridge

Andrea Puhm
CNRS researcher, CPHT, Ecole
Polytechnique, Black Hole Initiative Visiting Scholar

Title: On the distinguishability of black hole microstates

Abstract: ​A challenging question in the context of the information paradox is how to distinguish black hole microstates without having access to the entire spacetime. In the context of holography, one can ask how one can distinguish microstates of a black hole in anti-de Sitter space by measurements performed in the dual conformal field theory. I will discuss one...

Read more about BHI Colloquium, March 27 | "​On the distinguishability of black hole microstates," Andrea Puhm | "Discovery and Opportunity in the X-ray Time Domain," Daryl Haggard
2018 Mar 06

BHI Colloquium, March 6 | "Coherent Stacking of Multiple Gravitational Wave Events," Frans Pretorius | "Neutron Stars and Stellar Mergers as a Laboratory for Dense QCD Matter," Aleksi Vuorinen

1:30pm to 2:30pm

Location: 

BHI Conference Room (211) 20 Garden Street, Cambridge

Frans Pretorius
Princeton University

Abstract:
Within the next few years we can anticipate that the LIGO/Virgo detectors will have observed many tens or even hundreds of binary compact object merger events. One avenue to extract more information from this catalog is to stack the signals from a subset of events that are expected to share a common feature, enhancing the effective signal-to-noise ratio that the feature can be measured with. Thanks to the uniqueness properties of black holes in Einstein gravity, binary black hole mergers are ideal targets for stacking, allowing for stringent tests of dynamical, strong-field gravity, or detecting deviations from the predictions of general relativity.

I will describe an initial study exploring the utility of stacking to detect higher-order quasi-normal ringdown modes post-merger.

Though binary neutron star systems do not share such a uniqueness property, there may nevertheless be aspects of merger signals that could be enhanced using stacking. I will discuss one such example that would seek to detect a post-merger signal from the subclass of events where a hypermassive remnant forms.

 


Aleksi Vuorinen
Helsinki Institute of Physics

Abstract:
Outside the interiors of black holes, neutron stars contain the densest forms of matter in our present-day Universe. This makes them a unique laboratory for strong interaction physics, as novel phases of QCD matter may be present in their extremely dense cores, or produced at the high temperatures reached in stellar mergers. In my talk, I will concentrate on the quantitative constraints that various types of neutron star observations, including the gravitational wave signatures of their mergers, have recently set for the properties of dense nuclear and quark matter. In particular, I will demonstrate that the Equation of State of cold and dense QCD matter is significantly constrained by the known existence of two-solar-mass stars and by the recent LIGO constraint on the tidal deformabilities of the two stars involved in the gravitational wave observation GW170817.

2018 Feb 13

BHI Colloquium, February 13 | "Constraining LIGO Detectable Black Hole Mergers in AGN Disks," Saavik K. Ford | "X-ray Reverberation Mapping Accretion in AGN," Erin Kara

1:30pm to 2:30pm

Location: 

BHI Conference Room (211) 20 Garden Street, Cambridge

 

Saavik K. Ford
The City University of New York

Abstract:
I will present a model for stellar mass black hole binary (BHB) mergers accelerated by an active galactic nucleus (AGN) accretion disk. This model predicted the existence of 'overweight' stellar mass BHB mergers, detectable by LIGO (McKernan, Ford, et al. 2014). In more recent work, we find the rate of BHB merger by this channel can span the range 1e-4-1e4 Gpc^-3 yr^-1, depending on a
variety of poorly constrained astrophysical parameters. Thus, with LIGO's measured rates (12-213 Gpc^-3 yr^-1), we can already constrain some aspects of AGN physics. I will also present the predicted mass and spin spectrum of BH produced via this channel.
Notably, retrograde spin BH, evolving in a gas disk play a key role in the shape of the spin distribution among AGN-produced BHB mergers. Finally, I will discuss how this channel can be constrained by LIGO observations and other future theoretical and observational work.
 

Erin Kara
University of Maryland

Abstract:
Accreting supermassive black holes can produce more electromagnetic and kinetic luminosities than the combined stellar luminosity of an entire galaxy. Most of the power output from an Active Galactic Nucleus is released close to the black hole, and therefore studying the inner accretion flow--at the intersection of inflow and outflow--is essential for understanding how black holes grow and how they affect their surrounding environments. In this talk, I will present a new way of probing these environments, through X-ray reverberation mapping, which allows us to map the gas falling on to black holes and measure the effects of strongly curved spacetime close to the event horizon.

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